Archive for December 2016

Low Cab Forward Medium-Duty Trucks

The all-new Low Cab Forward medium-duty trucks are the latest in a long line of Chevrolet models in the commercial market. (Fig. 1) The seven new Low Cab Forward models, offered in regular cab or crew cab body styles, are the 3500, 3500HD, 4500, 4500HD, 4500XD, 5500HD and 5500XD. The trucks area available with a variety of upfit equipment and bodies provided by independent suppliers.


F01 LCF trucks 1

Fig. 1


Depending on the model, the trucks are equipped with either a GM 6.0L V8 gasoline engine, a GM 6.0L V8 LPG/CNG-capable engine, or an Isuzu 3.0L or 5.2L I4 turbocharged diesel engine.




3500 and 4500 Configurations


Available in regular cab and crew cab configurations, the 3500 and 4500 models are equipped with a Vortec 6.0L V8 engine (RPOs L96, LC8) and mated to a Hydra–Matic 6L90 6-speed automatic transmission (RPO MYD).


3500HD Configuration


The 3500HD truck is equipped with an Isuzu 3.0L I4 turbocharged engine (RPO IZ3) and an Aisin A460 6-speed automatic transmission (RPO IX0). It’s available in a regular cab configuration.


4500HD and 4500XD Configurations


The 4500HD and 4500XD models are equipped with an Isuzu 5.2L I4 turbocharged engine (RPO I1B) with an Aisin A465 6-speed automatic transmission (RPO IR7). These models are available in regular cab and crew cab configurations.


5500HD and 5500XD Configurations


The 5500HD is available in regular cab and crew cab configurations while the 5500XD is available as a regular cab model. These trucks are equipped with an Isuzu 5.2L I4 turbocharged engine (RPO I1B) and an Aisin A465 6-speed automatic transmission (RPO IR7).




Regular cab models equipped with 6.0L V8 gasoline or LPG/CNG engines – The engine oil dipstick can be found on the left side of the engine after tilting the cab.


Crew cab models equipped with 6.0L V8 gasoline or LPG/CNG engines – The engine oil dipstick is under the engine inspection sub-cover underneath the passenger seat. Use the strap on the front of the seat to raise the seat cushion. Release the sub-cover catch hooks to raise the cover for access to the oil dipstick.


Regular and crew cab models equipped with 3.0L I4 or 5.2L I4 diesel engines – The engine oil level can be checked using the oil level switch on the left side of the instrument panel. (Fig. 2) When checking the oil level, be sure the vehicle is on level ground and the engine is cool. Press the engine oil level check switch on the instrument panel. If the oil level is low, the red oil pressure warning light will turn on. If the engine oil level is acceptable, the green oil level indicator will turn on. The oil level also can be checked using the oil level dipstick.


F02 LCF button 3

Fig. 2




Diesel Engine Coolant


The diesel engines use a long-life coolant that is green in color. The addition of conventional green propylene glycol coolant will damage the engine. The factory-installed long-life green engine coolant is not available from GM Customer Care and Aftersales. Use only yellow long-life coolant (GM P/N 12378560; ACDelco P/N 10-5034) in the Low Cab Forward diesel engines. It is the only product that has been certified as compatible with the original long-life green diesel engine coolant.


A fuel system cooler (Fig. 3) has been added to models equipped with the 5.2L I4 diesel engine. The fuel system cooler compensates for increased fuel pressure and increased cylinder pressure due to changes in the camshaft timing, which results in higher fuel temperatures. The cooler reduces the fuel temperature prior to the fuel returning to the fuel tank. The cooler is mounted in front of the rear axle.


F03 LCF cooler 5

Fig. 3


Diesel Emission Systems


The 3.0L and 5.2L diesel engines use a Diesel Particulate Filter (DPF) system with a Diesel Oxidizing Catalyst (DOC) and a Selective Catalytic Reduction (SCR) assembly to meet current diesel emissions standards. (Fig. 4)


F04 LCF emission sys 6

Fig. 4


The DPF system that is designed to capture particulate matter (PM), or soot, is the same on both diesel engines except that the 3.0L system does not have a DPF fuel injector in the exhaust system for regeneration. The 3.0L system uses post injection from the main injectors during a DPF regeneration event instead of a DPF fuel injector.


Diesel Exhaust Fluid


The Diesel Exhaust Fluid (DEF) tank is installed on the frame on the left side of the vehicle. It includes a Level & Temperature Sensor, a drain plug and a tamper-resistant filler insert to prevent filling with fluids other than DEF. A visual DEF level gauge is helpful when filling the tank. (Fig. 5) The internal pickup includes the Coolant Heating Tube and Gauge Sending Unit. The pickup is serviced as a complete assembly.


F05 LCF DEF tank 7

Fig. 5


The DEF gauge (Fig. 6) on the instrument cluster indicates the quantity of DEF remaining in the DEF tank. When only one green bar is showing, the DEF tank is almost empty and should be refilled soon. If the vehicle is driven too long with only one bar, the green will change to amber and additional warnings and indicators will display. Vehicle speed will be severely limited when the DEF tank is empty.


F06 LCF DEF gauge 8

Fig. 6


The DEF indicator lamp on the instrument cluster will illuminate if there is a malfunction of the SCR system, the DEF level is too low or empty, of the DEF tank is refilled with any fluid other than DEF.




Vehicle Pigtail Connector


The Low Cab Forward trucks use the vehicle pigtail connector as the communication gateway (similar to the Diagnostic Link Connector, or DLC, on other GM vehicles) from which a Vehicle Health Report can be downloaded. The connector is accessible after removing the relay fuse cover in the center of the lower dash panel. Behind the panel, the connector is located in the lower right corner of the opening. It has a green identifying mark under the clear plastic cover.


Connect the RS232 Cable (Fig. 7, #2), which is an essential tool, to the vehicle pigtail connector (Fig. 7, #1) and to a laptop USB port with GDS 2 installed. Once connected, the Vehicle Health Report can be downloaded. The ignition must be on with the engine off throughout the download procedure. Two blue lights on the RS232 cable will flash while the download is in process.


F07 LCF pigtail connector 9

Fig. 7




There are currently 90 service tools that a dealership may need for this program. However, each dealership’s actual tool cost and/or need is dependent on their current tool inventory. In addition, nine of the service tools are available through the Loan Tool Program.


For additional information on the Low Cab Forward medium-duty trucks, refer to Bulletin #16-NA-337.


– Thanks to Bob Briedis


Damaged Shipping Container Restraining Belts

Many service replacement engines, transmissions and transfer cases are delivered to dealerships in shipping containers that use a ratchet-style restraining belt. The belt is used to securely hold the component in place inside the shipping container. (Fig. 8)


F08 shipping case

Fig. 8


The shipping container also is used to return the core unit of the replaced component. Recently, some cores have been returned with the restraining belts cut, leaving the core unsecured in the container.


TIP: When the new component is received in the dealership, release the belt in the shipping container using the ratchet mechanism. (Fig. 9) Do not cut the webbing of the belt.


F09 shipping ratchet belt

Fig. 9


Secure the Core Unit


Once the core unit to be returned has been placed into the shipping container, use the belt to secure the core. Tighten the belt enough to prevent movement in the bottom of the container.


Core units returned to the Warranty Parts Center (WPC) or the Core Center that have had the belts cut (Figs. 10, 11), leaving the component unsecured, may be subject to a warranty claim debit.


F10 shipping belt 1

Fig. 10


F11 shipping belt 2

Fig. 11


Refer to the instructions now being included in the shipping containers for proper operation of the ratchet-style restraining belt and complete shipping instructions.


Containers with Damaged Belts


If a service replacement engine, transmission or transfer case assembly with a cut or damaged belt is received in your dealership, contact Matt Stedman by email at or by phone at 586-419-9370 with the details of your order. All belts in the containers are being inspected prior to shipping.


– Thanks to Mark Gordon

Two Fobs Needed for RKE Transmitter Quick Learn on 2017 Models

For 2017 model year vehicles, excluding Acadia Limited, Enclave, Traverse, Express and Savana models, adding a new Remote Keyless Entry (RKE) transmitter, or key fob, using the quick learn procedure requires that two previously learned transmitters be present. (Fig. 12)


F12 2 fobs

Fig. 12


TIP: If only one transmitter is present, the procedure will not complete and a Remote Learn Pending message will display on the vehicle’s Driver Information Center. The new transmitter will not be learned and cannot be reprogrammed.


If only one transmitter is available, use SPS to add a new transmitter to the vehicle instead of the quick learn procedure.


On 2016 and earlier model years, only one previously learned transmitter is needed to be present to perform the quick learn procedure.


Programming Additional Transmitters


The Adding Transmitters, also referred to as Adding Keys, programming does not erase any keys. The programming simply adds a key into the next available slot. Up to eight transmitters can be learned to a single vehicle. If a new transmitter is being learned to replace a damaged, inoperative, or stolen transmitter, follow the Replacing Transmitters procedure to ensure that an old transmitter cannot be used.


Before performing the quick learn procedure to add a transmitter, verify all mechanical keys operate correctly.


The quick learn procedure typically requires the two previously learned transmitters to be placed in the vehicle cupholder in the center console (if equipped) or to turn the ignition on/off with both transmitters.


To initiate programming, each new transmitter is placed in the transmitter pocket (Fig. 13), which is located in the center console storage compartment (if equipped) or the new key/transmitter is placed in the ignition switch. The ignition is turned to the ON position (do not crank the engine). The vehicle theft light on the instrument cluster will turn off or the Driver Information Center will indicate the key/transmitter is learned.


Be sure to keep other transmitters at least 12 inches (30 cm) away from the ignition switch or transmitter pocket while learning.


F13 transmitter pocket

(Fig. 13)


Refer to #PIC6208 for additional information on the quick learn procedure for 2017 models.


Refer to the appropriate Service Information for complete details on RKE transmitter programming for each specific GM model.


– Thanks to Chris Crumb

Shift to Park Message with Five DTCs Set

2017 Malibu and Volt models. These models are equipped with the 5ET50 automatic transmission (RPOs MKV, MKE), which is an electronically-controlled, continuously-variable electric transmission (or drive unit) on hybrid models. (Fig. 14)


2017 Chevrolet Volt Voltec Drive Unit

Fig. 14


The following DTCs may be set:

P1AEE – Drive Motor 1 Control Module Hybrid/EV Battery System Voltage High Voltage

P1AEF– Drive Motor 2 Control Module Hybrid/EV Battery System Voltage High Voltage

P1AF0 – Drive Motor 1 Control Module Hybrid/EV Battery Voltage System Isolation Lost

P1AF2 – Drive Motor 2 Control Module Hybrid/EV Battery Voltage System Isolation Lost

P1E22 – Auxiliary Transmission Fluid Pump Control Module Hybrid/EV Battery Voltage System Isolation Lost


If only two or three of these DTCs are set, follow the appropriate Service Information diagnostic procedures. The cause may not be any internal components of the transmission.


If all five DTCs are set, there is an internal fault with the transmission and the transmission requires replacement. Do not attempt any internal repairs.


Refer to #PIP5321 for more information on the Volt 5ET50 (RPO MKV) transmission restriction program.


Refer to #PIP5390 for more information on the Malibu 5ET50 (RPO MKE) transmission restriction program.


Refer to this TechLink article for additional information on loss of isolation on high voltage systems.


– Thanks to John Riker

Service Know-How

The latest service topics from Brand Quality and Engineering are reviewed, including an update on the new 2017 Service Training Standards and how to perform a software update on the AFIT diagnostic tool. (Fig. 15)


F15 EI image 2

(Fig. 15)


To view Emerging Issues seminars:

• Log in to • Select Resources > Video on Demand > GM STC > Search Videos; or • Select Catalog to search for the course number, and then select View > Take or Continue Course

New Essential Tool GE-52200 Propulsion System Lift

The new GE-52200 Propulsion System Lift table (Fig. 1) is designed for the removal/installation of electrical vehicle batteries as well as engines, transmission, transaxles, fuel tanks, suspensions, cradles and chassis system components.


Chevrolet Bolt EV dealerships are the first recipients of the GE-52200 lift table. All other U.S./Canadian dealerships will begin receiving the table as an essential tool in late 2017 or early 2018.


F01 lift table 1

Fig. 1


The air/hydraulic lift table has a capacity of 1,760 lbs. (798 kg) and a maximum lift height of 70 inches (178 cm), which can be actuated with a foot control pump. (Fig. 2) Connecting to shop air requires a quick connect fitting (not included).


F02 lift table air

Fig. 2


It features a 60/40 split table top that allows powertrains to be separated while mounted to the table. (Fig. 3) The length of the table is adjusted by releasing the pins and sliding the table in or out. It automatically locks into position at several set points.


F03 lift table top

Fig. 3

The lift handle can be quickly attached to either side of the lift using quick-release pins. The lift table also is easy to move around the service bay. The 360-degree swivel casters have integrated foot butterfly locks and detent locks for directional movement control. (Fig. 4)


F04 lift table caster

Fig. 4


This Lift Table Promotional PDF provides additional information.


Bolt EV High-Voltage Battery Removal


During removal of the high-voltage battery pack (also referred to as the drive motor battery), vehicle weight will be redistributed. Secure the vehicle to the lift/hoist arms with straps so that the vehicle does not become unstable on the hoist. Also support the vehicle with jack stands at the opposite end from which any major components are removed.


There is a Center of Gravity (C.G.) mark on the drive motor battery tray to locate the lift table. (Fig. 5) The high-voltage battery pack mass is approximately 1,000 lbs. (450 kg).


F05 Bolt EV battery CG

Fig. 5


Remove all connectors and mounting fasteners (Fig. 6) from the drive motor battery before lowering the lift table. Secure the battery to the lift table with straps.


F06 Bolt EV bolts

Fig. 6


– Thanks to Chuck Berecz

Sort It Out — New Service Information Table Sorting Features

The GM Service Information has implemented a number of new features recently designed to make it easier and more efficient to quickly access the information needed in the service bay every day.


Table Sorting


One of these new features is the ability to now sort the tables of the Master Electrical Component List. The list provides the component code, name, option code, location of the component on the vehicle, a link to the locator view, and links to related connector end views.


Users can now sort any column by selecting the directional arrows at the top of each column heading. (Fig. 7)


F07 MEC list 1

Fig. 7


The table also can be filtered by inputting a search word in the box at the top of the column. For example, under the Name column, enter “transfer” to filter the results with transfer in the name. (Fig. 8)


F08 MEC list 2

Fig. 8


Labor Time Guide Search


Another new feature of the Service Information is the Labor Time Guide search function. Use the search function to find a labor time by the labor operation number. Select “Titles” in the search box and then enter the labor operation number. The corresponding labor time guide will be displayed. (Fig. 9)


F09 LTG sort

Fig. 9


– Thanks to Lisa Scott

Inductive Charging Test Tool Adapter

A new Test Tool Adapter (EL-51755-UPD) has recently been shipped to all GM dealerships for use with the EL-51755 Inductive Charging Test Tool. The charging test tool is used to verify the charging system operation in a GM vehicle. The adapter (Fig. 10), approximately the size and shape of a typical mobile phone, makes it easier to place the test tool in the correct location on both charging pockets and charging pads. Proper positioning is critical to ensure the charging coils of the charging surface and the mobile device, or test tool, line up correctly to allow charging.


F10 inductive charging test tool adapter 4

Fig. 10


Adapter Installation


To install the adapter on the test tool, thread the strap on the tool, from the back of the adapter, through the rectangular slot near the top of the adapter. Next, align the tool with the back of the adapter and press it into place. (Fig. 11) The adapter should remain attached to the tester at all times.


F11 inductive charging test tool adapter 1

Fig. 11


Wireless Charging Compatibility


The first step in diagnosing a wireless charging condition is to validate that the customer’s device is compatible with the vehicle charging system. The latest version of #PIC6049 lists compatible phone models and if a phone has built-in wireless charging capability or an available wireless charging case. It also provides the maximum dimensions for devices that can be charged. Large devices may not be compatible.


When testing the charging system, or charging a device, be sure to remove all objects from the charging pocket or pad. Coins, keys, cards, or other items trapped between the phone and the charging surface can prevent charging and may become very hot.


Refer to this recent TechLink article for examples of different charging systems and tips on charging a mobile phone. [LINK recent TechLink article TO]


Testing using the EL-51755 Test Tool


The EL-51755 Inductive Charging Test Tool should be reasonably centered in the pocket or pad to align with the vehicle sensor. The adapter allows the tool to simply be inserted into the pocket. (Fig. 12) It will fit snugly and will align properly once fully inserted. On a charging pad, place the tester flush with the rear of the pad. (Fig. 13)


F12 inductive charging test tool adapter 3

Fig. 12


F13 inductive charging test tool adapter 2

Fig. 13


For both the pad and pocket, ensure that the flat side (non-LED side) of the tool aligns against the flat charging surface. There is no need to remove the rubber sleeve from the pocket or pad for testing.


To verify the operation of the charging system, simply place the tool in the pocket or on the pad with the vehicle ignition on. If the tool’s wireless charging indicator illuminates after a few seconds, the charging system is operating properly and any charging concern may be caused by an incompatible or defective mobile device. If the charging indicator is off, continue diagnosis using the appropriate Service Information.


To complete the test successfully, the procedure may need to be repeated five times. Between each attempt, remove the tool and wait two seconds


For additional information on the tool, check out the January Emerging Issues Seminar 10217.01V available through the GM Center of Learning at In Canada, view the December 2016 TAC Talk video; Infotainment segment.


– Thanks to Chuck Berecz and Bob Wittmann

Unwanted Brake Apply in Reverse without Park Assist Activation

Some 2016-2017 CT6 and 2017 XT5 models may have an unwanted brake apply condition while in Reverse when there is no object behind the vehicle or around the vehicle. This condition may occur most often when the vehicle is cold in the morning (overnight cold soak) or has been sitting outside for several hours in colder temperatures.


The performance of the rear Short Range Radar Sensor may be degraded at cold ambient temperatures below 50°F (10°C), which may result in unintended brake activation while the vehicle is backing up.


The rear Short Range Radar Sensor, located behind the rear fascia (Fig. 14, XT5 shown), is designed to detect objects up to approximately 98 feet (30 meters). The rear Short Range Radar Sensor communicates with the Active Safety Control Module via serial data on the object detection bus as part of the backing warning system and the rear automatic braking system.


F14 XT5 sensor R

Fig. 14


Once the rear Short Range Radar Sensor warms up to temperatures above 50°F (10°C), the condition is not present and may not be duplicated in the dealership.


Do not replace any parts or attempt any repairs for this condition. GM Engineering is determining a root cause. To address this condition at this time, use remote start to start the vehicle before driving, which will allow the rear Short Range Radar Sensor to warm up, or turn off the Park Assist feature (Fig. 15, CT6 shown) when backing up after a cold start.


F15 CT6 park assist

Fig. 15


– Thanks to Katul Patel

Harsh Shifting on the 8L90 Automatic Transmission

There may be several harsh shifting conditions on some 2015-2016 Silverado, Sierra, Yukon and Escalade models equipped with the 5.3L engine (RPO L83) or 6.2L engine (RPO L86) and the 8L90 automatic transmission (RPOs M5U, M5X). The shift conditions may include:

• Harsh 1-2 upshift (except for the first 1-2 upshift of the day) • Harsh 3-1 downshift when de-accelerating to a stop • Harsh downshift under heavy throttle apply • Active Fuel Management (AFM) V4 to V8 transition harshness (6.2L engine only) • Coast-down downshifts (6.2L engine only)


There is new Engine Control Module (ECM) and/or Transmission Control Module (TCM) software that is available to improve these conditions. Use the Service Programming System (SPS) and follow the on-screen instructions to complete the programming. If both controller options are listed in SPS, select K20/K71 Transmission Control Module.


Do not install this calibration if the vehicle is not exhibiting these conditions. It is not intended to be installed on these vehicles for any other conditions.


TIP: Installation of the new TCM software will require that the Transmission Service Fast Learn (SFL) procedure be performed using GDS 2 or SPS through the TIS2Web application. The transmission may exhibit poor shift quality until the clutch values are learned. Performing the SFL will reset and relearn all the shift adapts.


After the programming of the TCM (Fig. 16) is complete, evaluate the shift quality of the transmission. Refer to Bulletin #16-NA-019 for more information about the transmission adaptive functions, how to learn the clutches and improve shift quality.


TIP: Due to the installation of the new TCM software, Bulletin #14-07-30-001 should not be used on 2015 model year vehicles. It will not allow for proper clutch learning.



Fig. 16


Transmission Shift Adapts


The 8-Speed automatic transmission (Fig. 17) uses a line pressure and volume control system during upshifts to compensate for new transmission build variation as well as the normal wear of transmission components. The variation from new and normal wear of the apply components within the transmission over time can cause shift time (the time required to apply a clutch) to be longer or shorter than desired.


2015 Hydra-Matic 8L90 (M5U) Eight Speed RWD Automatic Transaxle

Fig. 17


In order to compensate for these changes, the TCM adjusts the pressure commands to the various pressure control (PC) solenoids to maintain the originally calibrated shift timing. Referred to as “adaptive learning,” this adjusting process ensures a consistent shift feel and increases transmission durability. Transmission adapts can be reset and relearned using the Transmission Service Fast Learn procedure that is completed in the service stall.


When the Service Fast Learn is complete, perform a test drive and note any soft or harsh shifts. Within GDS 2, a Transmission Service Fast Learn Data page is available to aid in performing adaptive learning by showing throttle percentage, engine speed, transmission fluid temperature, and gear command.


For additional information, refer to this TechLink article on reprogramming the 8L90 transmission or the TechLink article providing an overview of the new 8L90 transmission.


– Thanks to Matt Bunting and Dave Peacy

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