Archive for November 2015

New 2.8L Duramax Diesel Available in 2016 Colorado and Canyon

The new 2.8L Duramax turbo-diesel 4-cylinder engine (RPO LWN) is the cleanest diesel truck engine ever produced by GM. The new diesel engine (Fig 1.) will be offered in 2016 Colorado and Canyon LT and Z71 Crew Cab models with 2WD or 4WD and the Hydra-matic 6L50 6-speed automatic transmission (RPO MYB).


F01 diesel engine

Fig. 1


2016 Colorado and Canyon models with the new Duramax diesel engine also feature an all new integrated trailer brake controller as well as a smart diesel exhaust brake system that enhances vehicle control and reduces brake wear on steep grades.


The 2.8L Duramax diesel engine, which generates 181 horsepower and 369 lb.-ft. of torque, has a compression ratio of 16.5:1. It features a common rail direct injection fuel system, dual overhead camshafts (DOHC), 16 valves with a roller finger follower actuator system, and a water-cooled variable geometry turbocharger (VGT).


Engine Oil


The engine also uses an integrated engine oil filter and an integrated engine oil cooler. (Fig. 2) The oil filter is a cartridge-style paper filter designed for ease of service and accessibility on the vehicle. The engine requires engine oil that meets the dexos2™ specification. Use oil with a 5W-30 viscosity grade. In extreme cold areas (temperatures below –20°F or –29°C), 0W-40 oil may be used.


F02 diesel oil cooler

Fig. 2




The variable geometry turbocharger (VGT) used on the 2.8L engine is water cooled and bolted to the exhaust manifold of the engine.


Turbocharger components (Fig. 3): 1. Vanes; 2. Turbine blades; 3. Turbocharger fresh air intake; 4. Compressor and blades


F03 diesel turbo

Fig. 3


The VGT body assembly contains a contact-less inductive VGT position sensing element that is managed by a customized integrated circuit. The VGT position sensor is mounted within the VGT body assembly and is not serviceable. The ECM supplies the VGT body with a 5 V reference circuit, a low reference circuit, an H-bridge motor directional control circuit, and an asynchronous signal/serial data circuit. The VGT position sensor provides a signal voltage that changes relative to VGT vanes angle. The customized integrated circuit translates the voltage based position information into serial data using the J2716 Single Edge Nibble Transmission (SENT) protocol. The ECM decodes the serial data signal and is used as voltages for the VGT position sensor.


The turbocharger vanes are normally open when the engine is not under a load. The ECM will close the turbocharger vanes to increase engine power and to create a high pressure, using boost pressure actuator. The ECM will often close the turbocharger vanes to create back pressure to drive exhaust gas through the exhaust gas recirculation (EGR) valve as required. At extreme cold temperatures, the ECM may close the turbocharger vanes at low load conditions in order to accelerate engine coolant heating. The ECM may also close the turbocharger vanes under exhaust braking conditions.


Exhaust Aftertreatment System


The diesel exhaust aftertreatment system is designed to reduce the levels of hydrocarbons (HC), carbon monoxide (CO), oxides of nitrogen (NOx), and particulate matter (PM) remaining in the vehicle’s exhaust gases. Reducing these pollutants to acceptable levels is achieved through a 4-stage process.


1. The close coupled diesel oxidation catalyst (DOC) stage.

2. The selective catalyst reduction (SCR) stage.

3. The diesel oxidation catalyst (DOC) stage.

4. The exhaust particulate filter (EPF) stage.


The main components of the exhaust aftertreatment system are (Fig. 4): 1. Diesel Oxidation Catalyst (DOC) converter; 2. Selective Catalyst Reduction (SCR) converter; 3. Diesel Oxidation Catalyst/Diesel Particulate Filter (DPF)


F04 diesel exhaust

Fig. 4


Close coupled diesel oxidation catalyst (DOC) converter – The DOC converter functions much like the catalytic converter used with gasoline fueled engines. The DOC must be hot in order to effectively convert the exhaust HC and CO into CO2 and H20.

Selective catalyst reduction (SCR) converter – Diesel engines generate high levels of NOx. In order to meet today’s NOx limits, an SCR catalyst, along with diesel exhaust fluid (DEF), is used to convert NOx into N2, CO2, and H2O.

Diesel oxidation catalyst/diesel particulate filter (DPF) – The DOC reduces emissions and generates the exhaust heat needed by the DOC stage. Exhaust gas temperature sensors are located upstream and downstream of the DOC. By monitoring the temperature differential between these two sensors, the ECM is able to confirm DOC light-off. In order to generate the high exhaust temperatures needed for regeneration, the aftertreatment system increases exhaust temperatures by using the low pressure diesel hydrocarbon injector to inject diesel fuel into the exhaust gases prior to entering the DOC. The added fuel is not combusted but is oxidized by the DOC to create heat.


Diesel Exhaust Fluid


Diesel exhaust fluid (DEF), also called emission reduction fluid and/or reductant, is a mixture of deionized water and urea. The DEF tank holds approximately 5 gallons (19 liters) of reductant. An ECM controlled pump within the reservoir supplies pressurized reductant through a supply pipe to the emission reduction fluid injector.


The DEF tank is mounted beneath the bed. A full tank should last approximately 7,500 miles (12,070 km) under normal use. The blue DEF fill cap is next to the diesel fuel fill cap behind the vehicle fuel fill door. (Fig. 5) Do not overfill the DEF tank. DEF freezes when exposed to temperatures below 12°F (−11°C). This is normal.

F05 diesel fill


Fig. 5




The normal regeneration process removes captured particulates through incineration within the EPF. Regeneration occurs when the ECM calculates that the particulate level in the filter has reached a calibrated threshold using a number of different factors, including engine run time, distance traveled, fuel used since the last regeneration, and the exhaust differential pressure.


In general, the vehicle needs to operate continuously at speeds above 30 mph (48 km/h) for approximately 20-30 minutes for a full and effective regeneration to complete. During regeneration, the exhaust gases reach temperatures above 1,022°F (550°C). If exhaust gas temperatures fall below a normal calibrated threshold, regeneration will be terminated and a corresponding DTC should set. If a regeneration event is interrupted for any reason, it will continue, including the next key cycle, when the conditions are met for regeneration enablement. Normal regeneration is transparent to the customer. The self-cleaning occurs approximately once per tank of fuel.


A scan tool is required for service regeneration. Commanding a service regeneration is accomplished using the scan tool output control function. The vehicle will need to be parked outside the facility and away from nearby objects, due to the elevated exhaust gas temperature at the tail pipe during regeneration. The service regeneration can be terminated by applying the brake pedal, commanding service regeneration OFF using the scan tool, or disconnecting the scan tool from the vehicle.


There are two regeneration Driver Information Center messages. “Cleaning Exhaust Filter Continue Driving” will appear on the DIC when an exhaust particulate filter cleaning is required. To clean the filter, drive the vehicle above 30 mph (50 km/h) until the warning message goes OFF. This will take about 30 minutes. When the “Cleaning Exhaust Filter Must Continue Driving” message is displayed, it is important to keep driving to clean the exhaust filter. This will take about 30 minutes.


Special Tools


For more information about the new 2.8L Duramax diesel engine, including a list of the new special tools released for the engine, refer to #PI1539.


– Thanks to Sherman Dixon

6L50 Automatic Transmission Centrifugal Pendulum Vibration Absorber

The new 2.8L Duramax diesel engine (RPO LWN) is paired with the Hydra-matic 6L50 6-speed automatic transmission (RPO MYB). The transmission (Fig. 6) incorporates a torque converter, an integral fluid pump and converter housing, a single and double planetary gear set, friction and mechanical clutch assemblies, and a hydraulic pressurization and control system.


F06 trans 1

Fig. 6


The torque converter, containing a pump, turbine and a stator assembly, acts as a fluid coupling to transmit power from the engine to the transmission. It also hydraulically provides additional torque multiplication when required. Within the torque converter is a pressure plate, also called the torque converter clutch, which provides a mechanical direct drive coupling of the engine to the transmission when applied. The torque converter clutch (TCC) is applied by fluid pressure, which is controlled by a TCC pressure control (PC) solenoid.


Torque Converter and Integrated CPVA


To control vibration and noise inside the vehicle cabin, a centrifugal pendulum vibration absorber (CPVA) is integrated into the torque converter. This is the first application of a CPVA in a GM transmission.


Components include (Fig. 7): 1. Torque converter assembly; 2. Torque converter transmission spline; 3. Pendulum masses; 4. Output hub


F07 trans 2

Fig. 7


Centrifugal Pendulum Vibration Absorber


The CPVA is an absorbing damper with a set of secondary spring masses that, when energized, cancel out the engine’s torsional vibrations. The spring masses vibrate in the opposite direction of the torsional vibrations of the engine, balancing out undesirable torsional vibrations.


CPVA components (Fig. 8) include: 1. Pendulum masses; 2. Output isolator spring; 3. Input isolator spring; 4. Output hub


F08 trans 3 pendulum

Fig. 8


– Thanks to Sherman Dixon

6.2L Engine Supercharger Noise

The supercharger on the 6.2L engine (RPO LSA) in the 2009-2014 CTS-V and 2012-2014 Camaro (Fig. 9) may exhibit several noises coming from the bearing, which are due to contamination of the lubricating grease. If these conditions are left unaddressed, the bearing may overheat and damage the supercharger.


2014 Chevrolet Camaro ZL1

Fig. 9


Noise Conditions


2009-2014 models may experience a rattling or knocking noise at mid-to-high mileage that is especially prominent at idle or a screeching noise or a screeching noise at mid-to-high mileage usually when cold.


A buzz noise (similar to a heat shield buzz) may be heard between 700-1300 RPM on 2014 models.


All model years may have a light to moderate rattling noise at idle in the supercharger that is not present when engine speed is increased to about 1200 RPM. This noise is a normal sound typical of superchargers.


Supercharger Cover Replacement


If these noise conditions are present on 2014 models, 2009-2013 CTS-V and Camaro models that have had a service replacement supercharger installed after November 2013, or on manual transmission models that have a flutter or rattle at low RPMs, replace the supercharger front cover.


Supercharger Replacement


On vehicles built prior to 2014 that have not had a service replacement supercharger installed after November 2013, replace the supercharger.


– Thanks to Tracy Lucas

Updated Wheel Nut Torque Specifications

The wheel nuts and wheel nut torque specifications have been updated on 2016 ATS, CTS and Camaro models.


Cadillac models


The 2016 ATS-V, CTS, and CTS-V built after the following VIN breakpoints have a new wheel nut torque specification of 190 Nm (140 lb.-ft.) and now use new silver wheel nuts (part number 9597846).

Screen Shot 2015-11-24 at 11.21.28 AM

The wheel nuts cannot be interchanged with wheel nuts on other ATS-V, CTS and CTS-V models built before the breakpoints. The earlier wheel nuts have a blue tint on the clamping surface and a different torque specification. (Fig. 10)


F10 Blue Magni Lugnuts1

Fig. 10


For replacement parts, the Service Parts Catalog will list the breakpoints and part numbers for both available wheel nuts. Be sure to check the part numbers when ordering parts.




2016 Camaro models have a new silver wheel nut with a different torque specification of 190 Nm (140 lb.-ft.). This applies to all 2016 Camaro models.


If installing accessory wheels on the 2016 Camaro, use the original wheel nuts with the silver clamping surface.


TIP: Do not use wheel nuts or security wheel locks with blue tint on the clamping surface for wheel installation on any 2016 Camaro.

Screen Shot 2015-11-24 at 11.22.10 AM


– Thanks to Jon Nowak and Holly Syriaque

USB Harness Power Supply Update

Some 2015 Acadia, Enclave and Traverse models may have a front console USB port losing power with the ignition key off or the USB music playlist restarting from the beginning after cycling the ignition.


Update the power feed harness to the front console USB connector for full-time battery power to address these conditions. Use TXL automotive grade jumper wire, a USB connector female terminal and an X340 connector female terminal to make a jumper wire for the X340 to USB connection. (Fig. 11)


F11 USB jumper wire

Fig. 11


Follow the instructions in Bulletin #15-NA-028 to build the jumper wire. The terminals should be located in the J-38125 Terminal Repair Kit.


To install the jumper wire, remove the right side of the floor console extension panel. Uncouple the large X340 connector with the white lever action CPA. (Fig. 12)


F12 USB X340

Fig. 12


Insert the large jumper wire terminal into the backside of cavity 18 in the connector. (Fig. 13)


F13 USB cavity 18

Fig. 13


The USB wire harness is sheathed in grey foam wrap at the back of the floor console USB port. Unplug the connector and use the purple J-38125-215A release tool to unseat the PK wire and terminal from the backside of the connector. (Fig. 14)


F14 USB usb terminal

Fig. 14


Insert the small jumper wire terminal into the backside of the USB connector. Clip the terminal off the PK wire and secure the wire with tape to the USB harness. Reconnect the USB connector to the USB port and test the USB port for full-time battery power.


– Thanks to Adam Frye

Adaptive Cruise Control Temporarily Unavailable

If an Adaptive Cruise Temporarily Unavailable message is displayed on the Driver Information Center of some 2015-2016 Escalade models equipped with the Driver Assist Package (RPO Y66), there are several items that should be considered during diagnosis, including environmental factors, component alignment, and system diagnostics.




Inspect the front view camera sensor on the windshield ahead of the inside rearview mirror to ensure it is attached properly to the windshield and not blocked by dirt, frost, or debris. If the windshield is cleared, the system may begin to operate.


Also check the front grill/fascia/lower air dam for a radar sensor blocked by excessive snow, ice, dirt, or debris. Keep the front of the vehicle clean for proper operation.


System operation may also be limited under snow, heavy rain, or road spray conditions.


Adaptive cruise control will function in Auto 4WD, but will be disable in 4WD HI range.


Very high ambient temperatures, such as those in the southwestern U.S. that may reach in excess of 100° F (38° C), may temporarily disable the Adaptive Cruise Control system. Refer to #PIC6123 for more information.


In many cases, these environmental issues do not set DTCs.




The Active Safety Control Module provides the Adaptive Cruise Control system functionality by analyzing data from the Long Range Radar Sensor Module, Front Short Range Radar Sensor Modules, and Front View Camera Module to identify and classify objects in the road environment.  If any of the radars or the camera becomes blocked or misaligned, an Adaptive Cruise Temporarily Unavailable message may be displayed and the Adaptive Cruise Control will be disabled. DTC B101E 4B (Unable to Learn Long Range Radar) may set.


Inspect for any aftermarket items (front grille, Cadillac emblem, etc.) or front end repairs (windshield, fascia, lower air dam, etc.). Some aftermarket parts may block or misalign the radars or camera.


Also inspect any components that may result in incorrect suspension trim heights, which may change what the radars detect and affect the operation of the system.  Refer to #PIT5403 for additional information.


In addition, the long range radar must be properly mounted and aligned. In most cases, misalignment is caused by a front end impact/collision, including contacting a parking curb, which may result in damage that is not obvious. Many of the new materials used for the front grilles, fascia, and lower air dams are very resilient and may not show any damage after a moderate collision, but the radar sensors or the sensor brackets behind the grille, fascia, or lower air dam may be damaged or misaligned.


TIP: Beginning mid-year 2015, the Long Range Radar Module (RPO AVF), was moved from behind the Cadillac emblem in the grille to below the front bumper impact beam behind the front fascia/air dam. (Fig. 15)


F15 radar module

Fig. 15


The Long Range Radar Module is scanning for objects up to 656 ft. (200 m) in front of the vehicle. (Fig. 16, green line) A slight bend in the radar bracket will cause the radar not to be able to detect objects farther out from the vehicle. (Fig. 16, red line) Check the alignment of the Long Range Radar Module bracket and then perform the GDS Long Range Radar Module Learn. If the Long Range Radar cannot detect objects throughout the full range of 656 ft. (200 m), the GDS relearn procedure will not complete, or it may fail or error out when performed.


F16 radar performance

Fig. 16


TIP: If there are no DTCs set or only DTC B101E 4B set, most vehicle issues may be resolved by performing the Long Range Radar Module bracket alignment and GDS Long Range Radar Module Learn procedure.


GDS can be used to review the Misaligned-Angled data in the Long Range Radar Sensor Module; go to Module Diagnostic > Long Range Radar Sensor Module > Data Display. There are four angled parameters to review: Up, Down, Left, and Right. If any of the parameters show “Yes,” this is a good indication the long range radar is misaligned.


Always perform a physical alignment check as well. Place the truck on an alignment rack to ensure a flat, level surface and use an angle gauge/level to check that the bracket is mounted 90 degrees (+/- 3 degrees) to the level alignment rack. (Fig. 17)


Perform the Long Range Radar Learn after correcting the alignment.


F17 radar angle

Fig. 17




Always check for any DTCs when diagnosing the Adaptive Cruise Control. Some DTCs may be related to subsystems used by the Adaptive Cruise Control system. If no DTC’s are found, use GDS to review the following data :

  • Active Safety Module – Adaptive Cruise Control Inhibit History Data and Adaptive Cruise Control Disengage History Data
  • ECM – Cruise Control Disengage History 1-8


Follow the appropriate Service Information to diagnose any of the items that have incorrect value.


– Thanks to Jim Will

Haptic Seat Operation during a Lane Keep Assist Event

The haptic seat (Safety Alert Seat) operation on 2015-2016 ATS, CTS Sedan (VIN A), and XTS models equipped with Lane Keep Assist (RPO UHX) varies depending on the Lane Keep Assist event. It’s important to understand the proper operation of the haptic seat before beginning any diagnosis. (Fig. 18)


F18 sas image

Fig. 18


Lane Keep Assist works differently than Lane Departure Warning in that it has two driver interventions: Stage 1 and Stage 2.


Stage 1 occurs when the vehicle is approaching a lane marking. In Stage 1, the Lane Keep Assist icon is solid amber and the Forward Camera Module is actively commanding torque to the electronic power steering. The driver should feel some feedback in the steering wheel, but there are no chimes or haptic seat activation.


Stage 2 occurs when the vehicle has crossed a lane marking by 40 cm or 15.75 inches. In Stage 2, the Lane Keep Assist icon is flashing amber and the Forward Camera Module is actively commanding torque to the electronic power steering. In addition, the Lane Departure Warning system sounds a chime and haptic seat activation occurs (if the setting is turned on in the Cadillac CUE vehicle settings).


Lane Keep Assist will be overridden if any of the following occur:

• High steering/rapid change in the steering position

• High braking/aggressive brake apply

• High/rapid acceleration

• High driver applied torque to the steering wheel

• Turn signal activation



Most commonly, the driver applies more torque to the steering wheel to overcome the Lane Keep Assist event. This would lead to the Lane Keep Assist fading out, and Stage 2 would not occur.


TIP: For Lane Keep Assist to be enabled, lane markings need to be of good quality and the curvature of the road and lane markings need to be less than a certain threshold.


– Thanks to David Antal

Loss of Steering Power Assist

An intermittent loss of power steering assist, a hard to steer condition or a Service Power Steering message displayed on the Driver Information Center may be found on some 2015 Colorado and Canyon models.

If these conditions are found, check the Power Steering Control Module for DTCs.


If DTC C056D (Electronic Control Unit Hardware) is set, reprogram the Power Steering Control Module with the latest calibrations using SPS.


If DTC C0545 (Steering Wheel Torque Sensor) is set, replace the power steering gear assembly. There are different steering gears for 2WD and 4WD models and short wheelbase or long wheelbase models.


For any other concerns, follow the diagnostics in the appropriate Service Information.


– Thanks to Ken Cole

Adaptive Cruise Control Technology Sets (and Maintains) the Pace

The Adaptive Cruise Control (ACC) System (RPO K59, KSG) available on 2014-2016 Impala, LaCrosse, Regal, ELR and 2015-2016 Tahoe, Suburban, and Yukon models is an enhanced cruise control system with the ability to sense and react to forward traffic. (Fig. 1) The system allows a driver to maintain a driver-selected set speed when no traffic is ahead as well as set and maintain a following time-based gap to the preceding nearest vehicle in the Adaptive Cruise Control vehicle’s path. The Adaptive Cruise Control System (RPO KSG) available on 2015-2016 Escalade models functions in a similar manner but has different hardware and display messages.


F01 Impala ACC R

Fig. 1


While in the following mode, the Adaptive Cruise Control vehicle’s distance sensor module controls the following speed to maintain the driver-selected following gap to the proceeding vehicle ahead. The system will automatically adjust the speed of the Adaptive Cruise Control vehicle when approaching a slower moving vehicle and will apply limited automatic braking or throttle control without driver input when necessary to maintain the following gap setting.


The preceding vehicle’s speed and acceleration and the Adaptive Cruise Control vehicle’s speed and acceleration along with the distance between the two vehicles are factors used by the Adaptive Cruise Control module to determine the appropriate following speed. Once the path ahead of the vehicle becomes clear, the Adaptive Cruise Control system will speed up the vehicle to the driver-selected set speed.


The ACC system (RPO K59) on 2015 and later Tahoe, Suburban and Yukon models, as well as 2014 and later Regal models equipped with a manual transmission, will operate down to a speed of 10 MPH (16 km/h). As these vehicles slow down in response to a slower moving vehicle ahead, a chime sounds when the system disengages and the driver is expected to assume control of the vehicle.


2014 and later Impala, LaCrosse, Regal and ELR vehicles equipped with an automatic transmission have the full-speed range ACC system (RPO KSG). Vehicles equipped with this system are capable of coming to a full stop as long as the vehicle ahead has been detected while still moving.


For either of these two systems, the vehicle speed must be above 15 MPH (25 km/h) and below 118 MPH (190 km/h) for Adaptive Cruise Control to be engaged by the driver.


Sensor Module


The Adaptive Cruise Control distance sensor module contains both the radar sensor and the controller. The radar scans the road environment to detect targets within its specified field of view. The controller then makes throttle and/or brake commands to the Engine Control Module (ECM) and Electronic Brake Control Module (EBCM) for proper cruise speed adjustment.


The radar processes the road environment to gather data concerning any vehicle ahead of the Adaptive Cruise Control vehicle. When an object is detected, the controller calculates the object range, range rate, acceleration and azimuth angle parameters.


The Adaptive Cruise Control vehicle’s distance sensor module performs Adaptive Cruise Control state processing automatically — speed control (the Cruise state) or gap control (the Follow state). The normal operating state is Cruise, whereby the vehicle speed is controlled (either brakes or throttle) in order to match the driver-selected set speed. When a preceding forward target is identified by the radar, the system will automatically transition into the Follow state and command the appropriate speed in order to maintain the driver-selected following gapbehind the target vehicle.


TIP: After programming the distance sensor module and while performing the learn procedure, the Service ACC message on the Driver Information Center (DIC) will display and the Vehicle Ahead indicator on the instrument cluster will flash to indicate that the radar is in the alignment mode and collecting data. The Service ACC message will extinguish and the Vehicle Ahead indicator will stop flashing when the radar module has completed the alignment process. The radar system should become functional once the learn procedure is complete and the diagnostic session is concluded.


Cruise Control Switch Functions


The cruise control function switches (Fig. 2) are used by the BCM to communicate all Adaptive Cruise Control commands to the Adaptive Cruise Control distance sensor module.


F02 cc switch

Fig. 2


The Adaptive Cruise Control switches are momentary-type switches that are hard-wired to the BCM. Based on voltage variations, the BCM is able to communicate driver commands to the Adaptive Cruise Control module. The initial press of the gap switch recalls the current setting and activates the display. Subsequent presses of the gap switch will change the gap setting (near, medium or far). The DIC displays the driver-selected following gap. This gap setting also applies to the Forward Collision Alert system and will impact how early or late the collision alert system will warn the driver. (Fig. 3)

F03 cc gap setting

Fig. 3


The gap switch allows the driver to determine how closely a target vehicle is followed while Adaptive Cruise Control is engaged. The gap switch has three following gap selections that range from 1 to 2 seconds. The distance maintained for a selected gap will vary based on vehicle speed. The faster the vehicle speed, the further back the vehicle follows.


Following Distance Indicator


The following distance is expressed in time as opposed to actual distance. If no vehicle is detected, dashes are displayed. (Fig. 4)


F04 cc distance display

Fig. 4


Vehicle Ahead Indicator


The Vehicle Ahead indicator is displayed on the instrument cluster when the radar identifies an in-path vehicle, and also serves as feedback that the radar is functioning properly. The Vehicle Ahead indicator may sometimes display for stationary road objects.


Mechanical Alignment


When the radar is out of alignment, DTC C1002 (Distance Sensing Cruise Control Module Performance) is set by the Adaptive Cruise Control distance sensor module. A persistent blockage warning can also be an indicator of misaligned radar. When DTC C1002 is set, the radar must be mechanically aligned using the special alignment tool. Refer to Forward Range Radar Module Alignment in the appropriate Service Information.


An out of alignment condition may result from tampering or damage to the Adaptive Cruise Control distance sensor module from a major or minor impact to the front of the vehicle. A damaged or misaligned radar module is not always obvious. Sometimes, damage can occur to the module or its alignment without any evidence of impact to the front of the vehicle.


When checking for a misaligned radar module, look for a bent mounting bracket or a module that is no longer properly attached at its attaching points on the mounting bracket. Misaligned radar can result in DTC C1002 being set, a recurring blockage warning message on the DIC, a reaction to target vehicles or objects in adjacent lanes or no reaction to target vehicles or objects in the vehicle’s path.


When aligning the Adaptive Cruise Control distance sensor module, the vertical position of module should be 90 degrees relative to the ground. Use a water bubble level to align the distance sensor module vertically. (Fig. 5) The bubble level should have an accuracy of +/-0.5 degrees (9 mm/m). Turn the alignment screw until the bubble level has a value of 90 degrees.


TIP: Before performing a radar alignment, always check the three ball sockets in order to insure that the module is properly attached to the ball studs on the mounting bracket.


F05 acc module

Fig. 5


– Thanks to Katul Patel and Brian Shenstone

Adaptive Cruise Control Radar Module Blockage Message

The 2014-2016 Impala (VIN 1), LaCrosse, Regal, ELR and 2015-2016 Tahoe, Suburban, and Yukon models equipped with Adaptive Cruise Control (RPO K59) may display a blockage message on the Driver Information Center (DIC) due to a blocked radar sensor. The Adaptive Cruise Control system is disabled if the radar is blocked.


Radar blockage detection is a normal part of Adaptive Cruise Control operation. If the radar is blocked, a “Front Radar Blocked Clean Front of Vehicle” message will display on the DIC. A blockage warning message may be displayed if.


• Weather conditions such as rain or heavy snow prevent the radar from being able to properly discriminate targets. This DIC message will clear shortly after the weather conditions improve.


• Rain, snow, ice, mud or debris collect on the front or the back of the fascia in the area of the radar or on the face of the radar module itself. This DIC message will clear shortly after the affected surfaces are cleaned.


• The radar module is no longer properly aligned. If a blockage warning is observed and the radar field of view is not blocked due to weather conditions or water, snow or mud on any of the surfaces, the module should be inspected to determine if it is properly mounted and aligned.




For each of these cases, the “Front Radar Blocked Clean Front of Vehicle” message on the DIC will clear following an ignition cycle where the vehicle is allowed to completely shut down. Once the ignition is turned back on, the radar module will rerun its blockage detection algorithm and, if the blockage condition still exists, will re-initiate the “Front Radar Blocked Clean Front of Vehicle” DIC message. While the blockage algorithm is running, a “Radar Temporarily Unavailable” message may be displayed. If the blockage message reappears after an ignition cycle, confirm all possible causes have been addressed.


Since radar blockage is a part of normal radar operation, the radar module should not be replaced when the blockage DIC message is displayed. Be sure to check the identified possible causes.


Cleaning the Vehicle


First, turn off the ignition before cleaning the fascia or module surfaces. When cleaning the front of the vehicle to eliminate a blockage, it may be necessary to clean both the outside surface of the front fascia, (Fig. 6) the inside surface of the fascia and the cruise control vehicle distance sensor module face.


F06 acc location

Fig. 6


Service ACC Message


If the cruise control vehicle distance sensor module detects a malfunction in the Adaptive Cruise Control (ACC) system, the SERVICE ACC message will display on the DIC. This message is displayed when a diagnostic condition is present, unlike the blocked radar message.


– Thanks to Brian Shenstone and Katul Patel

Adaptive Cruise Control DTCs in History

The 2014-2016 Impala (VIN 1), LaCrosse, Regal, ELR and 2015-2016 Tahoe, Suburban, and Yukon models equipped with Adaptive Cruise Control (RPO K59) may have a DTC set in history due to a communication issue during vehicle start-up.


DTCs P1553 (Distance Sensing Cruise Control Signal Message Counter Incorrect) and/or P15F6 (Front Object Detection Control Module Torque Request Signal Message Counter Incorrect) may be set when the Adaptive Cruise Control subsystem components power up after some ignition cycles. These two DTCs will quickly transition to history. This is a known issue that has no impact to the operation of the Adaptive Cruise Control system. The Adaptive Cruise Control module should not be replaced based on these two codes being observed in history status.


– Thanks to Brian Shenstone and Katul Patel

MDI/MDI 2 Manager Software Installation


GM recently began rolling out new MDI Manager software. This software includes updates for the upcoming MDI 2 hardware. It’s compatible with the current MDI and the new MDI 2, to be released soon, and operates in a similar manner to the existing version.


Here are some items to keep in mind when installing the new software.


Update all MDIs and Computers


A user will be prompted to install the MDI/MDI 2 Manager software when clicking the SPS or GDS2 icon in TIS2Web. It is recommended to update all MDIs and Service computers at the same time to avoid incompatibility issues. Once an MDI is updated, it will not connect to another computer with the old MDI Manager software.


Encrypt Your Wireless Network


There are some changes in the new software that affect the connection method. Open/unencrypted wireless network configurations are no longer supported in the latest software version (update During installation of the new MDI/MDI 2 Manager software, network settings will be deleted if the network is not encrypted. When the user inputs the settings again, they will be deleted once again from the device when the MDI/MDI 2 power is cycled. 


A form of encryption must be used on all wireless access points when configuring and using the MDI or MDI 2. Check the current GM Dealer IT Guidelines for detailed information on wireless encryption recommendations and requirements.


Also, if any firewall or antivirus software is running, it must be configured to allow the new MDI/MDI 2 Manager to pass through. This will be recognized as new software by many firewalls and they often block it by default. TCSC does not configure firewalls. Contact your local dealership IT support for assistance.


Plug in the MDI to Update the Firmware


By plugging in the USB cable to the PC, the MDI Manager should recognize the MDI over USB by default. The MDI must be connected over USB in order to update the firmware on the MDI. The icon will indicate the method of connection and will be displayed over top of the MDI icon in the MDI Manager.


Bad Cable Connection


If the USB cable is plugged in and there is a wireless connection icon on the MDI, it may be due to a bad USB cable, bad USB port on the MDI, bad USB port on the computer or a firewall is blocking it. Swapping cables, MDIs and computer ports will confirm the problem.


For assistance, contact the Techline Customer Support Center (TCSC) at 1-800-828-6860 (English) or 1-800-503-3222 (French).


– Thanks to Chris Henley


Updated November 12, 2015


Latest AFIT Tool Adapters Released

Several new control modules on 2016 GM models use new sensor technology. The SAE J2716 SENT (Single Edge Nibble Transmission) protocol allows for high resolution data transmission from a sensor to a control module, such as readings for temperature, pressure, throttle position and mass airflow. This new technology requires new adapters for the CH-47976-500A Active Fuel Injector Tester (AFIT).


The CH-47976-507 AFIT SENT Fuel Sensor Adapter is an adapter with molded-in internal active circuits and a digital-to-analog signal conversion processor that allows the AFIT SIDI adapter cables to function and test the injectors and the fuel system on vehicles with the SENT system.


Follow the instructions included with the CH-47976-507 SENT Adapter to permanently attach the adapter to the AFIT Drive and Measurement Unit (DMU). Once the adapter is attached, the DMU is compatible with both SENT and non-SENT fuel pressure transducers so it can stay connected permanently to the DMU. The various AFIT SIDI adapter cables then connect directly to the SENT Adapter.


TIP: To help in determining which adapter to use, the AFIT will display the correct adapter during the testing process. The latest software must be used in order to display all correct adapter and cable selections.


CH-47976-513 AFIT SENT Cable Adapter


An adapter compatible with the SENT technology and E92 engine control module used on the fuel system of the 2016 ATS, CTS and XTS equipped with the turbo-charged 3.6L V6 was not available at the start of production, but has now been shipped to dealerships.


These models require an added adapter to allow the previously essential CH-47976-502A Cable to be used. Use the CH-47976-513 Cable Adapter, the CH-47976-502A Cable, and the CH-47976-507 SENT Adapter for diagnostics with the AFIT.


CH-47976-512 AFIT SENT Cable Adapter


The fuel system on 2016 Malibu, Encore, ATS, CTS and other upcoming 2016 models with the E80 engine control module and the Stop/Start system use a SENT fuel rail pressure sensor. GM Stop/Start systems have a secondary circuit that must be energized to crank the engine and build fuel pressure in the fuel rail for AFIT SIDI tests. Due to the digital-to-analog signal conversion requirement of the SENT transducer, a software update and the CH-47976-512 Adapter is needed to convert the fuel pressure digital signal coming from the transducer into an analog signal that the AFIT can interpret and use for fuel system performance analysis and test results.


The CH-47976-512 Adapter with internal active circuits enables the previously essential CH-47976-503 Cable to be used on vehicles incorporating SENT fuel pressure transducers and Stop/Start systems. Connect the CH-47976-512 Adapter to the CH-47976-503 Cable, which connects to a DMU modified with the CH-47976-507 SENT Adapter. This allows vehicles with SENT systems on both standard and Stop/Start vehicles to be tested.


Software Updates


The software version update to activate the SENT Adapters is available for download through the Service Workbench selection of “Essential Tools – Software Updates” on GM GlobalConnect (U.S. only).


For software updates and additional information go to


In Canada, the software is available through the Dealer Equipment Services (DES) Canada website. A link to this site is located in GlobalConnect under Service Department Quick Links; look for “Essential Tools – Software Updates.”


– Thanks to Chuck Berecz

Proper Air Cleaner Outlet Duct Cover Removal

When removing the air cleaner outlet duct cover, also referred to as the engine cover, on the 2015-2016 Colorado and Canyon equipped with the 3.6L V6 engine (RPO LFX), all fasteners must be fully removed in order to avoid damaging the cover. The cover does not use any fasteners that snap into place.


To properly remove the cover (Fig. 7, B) from the air cleaner assembly (Fig. 7, A), follow the instructions outlined in the appropriate Service Information.


F07 engine 36L

Fig. 7


Keep these tips in mind while performing any service that requires removal of the cover:

• Disconnect the PCV tube and unclip the PCV tube from the air cleaner outlet duct cover. The tube has a plastic collar quick connect fitting.

• Remove the oil fill cap (Fig. 8, #1) from the air cleaner outlet duct cover. (Fig. 8, #3)

• There are four bolts that secure the cover. (Fig. 8, #2) One bolt is located at the front of the cover and three at the rear of the cover. Make sure all bolts are completely removed before trying to remove the cover. The rear bolt closest to the air cleaner outlet duct is often overlooked. The cover cannot be removed unless all bolts have been removed first.



F08 engine 36L cover

Fig. 8


– Thanks to Charles Hensley

Security Code Required during Programming

When programming certain modules on 2015 Encore, Sonic, Spark and Trax models, a security code may be requested at the Techline PC.


The security code is listed in GM GlobalConnect along with the Key code, which is labeled as the IMMO code. (Fig. 9) The Key Code application is restricted to authorized users.


F09 key code image

Fig. 9


In the U.S., the Key code is located in the GlobalConnect App Center under the Parts and Business Office departments.


In Canada, use the D2D link located in the GlobalConnect App Centre under the Parts department. If the required IMMO code is not found, contact the Dealer Systems Support helpdesk.


In the dealership, contact your Dealer Partner Security Coordinator to identify authorized users at your facility.


– Thanks to Matthew Zajechowski

Service Engine Soon Lamp and Reduced Power

Some 2016 Escalade models, Silverado 1500, Suburban, Tahoe, Sierra 1500 and Yukon models equipped with the 4.3L engine (RPO LV3), 5.3L engine (RPO L83) or 6.2L engine (RPO L86) may have an illuminated Service Engine Soon (Check Engine) lamp or a reduced power message displayed on the Driver Information Center. Several Accelerator Pedal Position (APP) DTCs may set (including P0106, P0107, P0697, P2122, P2123, P2127, P2128 or P2138).


The ECM scan tool parameter also may show a 5-Volt Reference 3. This parameter displays the voltage sensed on the 5-volt reference circuit at the ECM.


Follow the appropriate Service Information for the DTCs that have set. Also inspect the wiring harness near the left instrument panel junction block. (Fig. 10, #1) The wiring harness (Fig. 10, #3) may have been pinched at the mounting stud. (Fig. 10, #2) Repair any damaged circuits as necessary.


F10 app wiring

Fig. 10


– Thanks to Richard Renshaw

Service Know-How

10215.11D – Emerging Issues

November 12, 2015


To view Emerging Issues seminars:

• Log in to

–   Select Resources > Service Know-How/TECHAssist > Emerging Issues > Searchable Streaming Video; or

–   Select Catalog to search for the course number, and then select View > Take or Continue Course

New Bulletin Review – October 2015

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