Archive for March 2012

Service Know-How

10212.03D – Emerging Issues

March 8, 2012


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Transmission Control Module Connector Terminals

The 2008-2012 CTS equipped with a 6-speed automatic transmission may exhibit an intermittent no crank/no start condition along with an intermittently illuminated Service Engine Soon lamp. DTCs U0100, U0121 and/or a U0101 may be set with no communication with the Transmission Control Module (TCM), Electronic Brake Control Module (EBCM), and/or Engine Control Module (ECM).


If this condition is present, check the round connector at the Transmission Control Module (Control Solenoid Valve Assembly) for any high-speed LAN wires that may be pushed out of the back of the connector.


After locating the high-speed LAN wires, gently pull on the wires to make sure they are seated correctly. The terminals may be pushed out of the connector body with damaged lock tabs on the terminal. Replace any suspect terminals and re-test.


– Thanks to Stephen Jacob

Intermittent Low Fuel Light

The low fuel light on some 2004-2011 Aveo, 2005-2009 Wave (Canada only) and 2009-2010 G3 models may appear to operate intermittently. It may be difficult to duplicate this condition, or to locate any diagnostic and/or description and operation information for the low fuel light in the Service Information.


The low fuel light is operated by a thermistor in the fuel pump module. The fuel keeps the thermistor cool. When the fuel level drops below approximately 1.7 gallons (6.4L), the thermistor is no longer submerged in the fuel and the voltage from circuit 172 begins to warm the thermistor, decreasing the resistance. After approximately six minutes, the low fuel light illuminates.


If the vehicle is turned off for a period of time and then restarted, the low fuel light may not come back on for approximately six minutes, depending on the thermistor temperature.


Based on operating conditions, the operation of the low fuel light may be normal. Do not replace any parts prior to testing the fuel level thermistor and circuits.


On most models, the fuel pump can be accessed without removing the fuel tank by removing the rear seat. Jump circuit 172 to 850 at the fuel pump module connector on the body side of the harness. If the low fuel light illuminates, the circuits and instrument panel cluster are OK. If the light does not illuminate, test the instrument panel cluster and circuits 172 and 850.


The thermistor resistance specification is 750 to 1100 Ohms at 77° F. As the thermistor warms up, the resistance drops. If the thermistor is within specification, verify the vehicle’s fuel level is below the thermistor. If it is not, follow the current version of #PIC3209C to verify the fuel level resistances and circuits from the sender to the Engine Control Module (ECM).


– Thanks to Ernest Haller

Trailer Brake Switch and Fretting Corrosion

Some 2008-2011 Avalanche, Silverado, Suburban, Tahoe, Sierra, Yukon, Yukon XL, Yukon Denali, and Yukon Denali XL models equipped with a Trailer Brake Controller (RPO JL1) may have DTC B3894 Symptom 5A (Stop Lamp Switch Circuit Plausibility) set and a Service Trailer Brake message displayed on the Driver Information Center.


The failure of many of the stop lamp switches that have been returned to the Warranty Parts Center for inspection and testing has not been confirmed. DTC B3894 may be setting due to a wiring/terminal fretting corrosion condition at the brake switch.


Prior to replacing any switches, inspect the terminals at the brake switch. The fretting corrosion condition is caused by a buildup of non-conductive insulating oxidized debris occurring between the two electrical contact surfaces of the connection or connector.


Fretting corrosion may be caused by any of the following:

• Vibration

• Thermal cycling

• Poor connection/terminal retention

• Micro motion

• A connector, component or wiring harness not properly secured resulting in movement


On low current signal circuits, this condition may cause high resistance, resulting in intermittent connections.


TIP: Fretting corrosion looks like little dark smudges on electrical terminals and appears where the actual electrical contact is being made. In less severe cases it may be unable to be seen or identified without the use of a magnifying glass.


To combat fretting corrosion, use clean, one-inch nylon bristle brush to apply dielectric lubricant to both the brake switch-side and the harness-side of the affected connector. Reconnect the affected connector and wipe away any excess lubricant.


TIP: Do not apply an excessive amount of dielectric lubricant to the connector or hydro lock may result when attempting to mate the connector.


– Thanks to James Will

Blank Back-Up Camera Display

On some 2012 Equinox and Terrain models equipped with a back-up camera (RPO UVC), the camera display may be blank or the image may be fuzzy. A “Check Surrounding Area” message also may be displayed.


This condition is typically found during PDI or early in the life of the vehicle. No DTCs are set. The poor image quality or blank display may be caused by one or more of the power, ground or video signal circuits shorted or open due to a poor connection.


TIP: Do not replace the back-up camera for this condition. The blank screen with a “Check Surrounding Area” message indicates the back-up camera voltage has reached the radio and is missing the video input.


Specific connector issues with the back-up camera may include terminals that are not seated or are bent, poor camera pigtail connection or video wires shorted behind the radio. Printing the wire schematic related to the camera circuits and the connecter end views for connectors X212, X900, X904 may be helpful.


The X212 connecter (Fig. 15) is located on the right-side kick panel just below the glove box. It contains the three camera video signal circuits 6974, 6972 and 6973. Check for any broken wiring and bent or backed-out terminals.


 Fig 15

If no connection conditions are found, inspect circuit 6972, video positive, and circuit 6973, video negative, from connector X212 back to the radio for an unwanted ground or open condition. Also inspect the wire harness routing for chafing and that shield circuit 6974 is grounded only at the camera end, not at the radio. Poor image quality is usually caused by an ungrounded shield wire for the video circuits.


In addition, inspect the UBEC fuse #54 for the Rear CAM 5A for an open circuit.


Disconnect and inspect X900 (behind the liftgate upper trim panel) (Fig. 16) and X904 (behind the liftgate lower trim panel) (Fig. 17) for bent or backed-out terminals. Verify resistance is 5 Ohms or less to ground and that voltage is 12V with the ignition off. Press the key fob Unlock button to turn on the Reverse lamps (circuit 24 powers the Reverse lamps and is only active when the engine is running and the transmission is in Reverse. Using the key fob to turn on the back up lamps/approach lighting is easier for testing purposes.)


 Fig 16

 Fig 17

If the connections test OK, disconnect the camera pigtail connection to check for bent, backed-out or loose terminals. With X904 connected, verify power, ground and Reverse input voltage at the connecter-side of harness call out 16.


– Thanks to Gordon Baillod

No Radio Reception, OnStar Fades while Driving

A 2012 Sonic with XM and the OnStar tri-band antenna may not have any radio reception (AM, FM or XM) and OnStar service may fade in and out while driving.


Inspect the antenna coaxial connections at the tri-band antenna for proper routing. (Fig. 14) The coaxial connections may be swapped at the body side of the harness at the antenna connector.


Fig 14

– Thanks to Ernest Haller

Double-Check Wheel Alignment Specifications

Before performing a steering wheel angle/front toe set or wheel alignment check/adjustment, be sure to verify the wheel alignment specifications for the vehicle. A number of complications may occur if the incorrect wheel alignment specifications are used.


Using the wrong wheel alignment specifications may be the result of:

• The vast variation in specifications depending on the type of vehicle, model year, and the RPO content — tire, suspension, and engine options being some of the most predominant

• The wheel alignment rack does not contain up-to-date specifications, which may cause some alignment measurements to show as out of specification, when they are really within specification

• Entering the VIN only into the wheel alignment equipment, which does not allow the determination of the pertinent option content on the vehicle — tire and suspension RPOs, for instance

• The frequency in which the wheel alignment rack specifications are being updated

• Not verifying the specifications indicated on the wheel alignment rack with the appropriate Service Information(SI)


Submitted warranty claims show several examples where the vehicle was within specification when it was placed on the wheel alignment rack and it was adjusted out of specification because a source of information other than SI was used to verify the vehicle specifications.


The only recommended source of current, accurate wheel alignment specifications (both targets and tolerances) is SI. It is also critical to ensure that the specifications selected correspond to the option content on the vehicle.


Not using the correct specifications as shown in SI at the time of repair may result in the warranty claim being subject to review. A copy of the current specifications in SI should be submitted with the claim.


For additional information about wheel alignment service, equipment, and warranty administration requirements, refer to Bulletin #05-03-07-009.


Click the flowchart (Fig. 13) for a summary of the wheel alignment information.

Fig 13


– Thanks to Dave McGillis

Steering Gear Replacement Guidelines

When diagnosing a steering condition on 2007-2010 Outlook, 2007-2012 Enclave and Acadia, and 2008-2012 Traverse models, there are several bulletins that should be reviewed before replacing the steering gear assembly. In many cases, a component in the assembly may be available and it is not necessary to replace the entire gear assembly.


Here’s a summary of possible steering wheel conditions:

• A squeaking/rubbing noise that sounds like it is coming from the steering column or intermediate shaft. Check for proper intermediate shaft grommet orientation. (Fig. 12) Refer to Bulletin #09-02-34-001B. If this does not correct the noise, replace the pinion shaft housing. Refer to #PI0029F.


 Fig 12

•A knocking/clunking noise from the steering gear, front suspension or front frame area. Check for loose steering gear bushings. Refer to Bulletin #10-02-32-001A.

 • A knocking/clunking noise at the end of the steering travel. This is a hydraulic knock, which is considered normal when present at the end of the steering travel. No repairs should be attempted for this condition.


Any of these conditions should not require a complete steering gear assembly replacement. Review these bulletins to ensure that a steering gear is not being replaced to correct any of these conditions. If a steering gear replacement is necessary for any reason, it is recommended to convert the steering system to the use of DEXRON VI as outlined in #PI0620 to prevent future repairs for a steering gear squeak noise.


– Thanks to Gary McAdam

Upgraded Special Tool Organization Website Features Tool Instructions and Images

The GM Special Tools Organization website managed by SPX (Kent-Moore) is designed to help dealerships manage their special tool inventory. Several updates have been implemented recently to the website to increase the use and organization of special tools.


The website is accessed via the GM Special Service Tools Website link provided in GlobalConnect Service Workbench. On the SPX home page for GM Special Service Tools, look for the GM Tool Organization link on the left side of the page. (Fig. 9) (In Canada, go to GlobalConnect Service Library > Tools, Processes and Equipment.)


 Fig 9

Tool Images and Videos


For 2012, new enhancements to the website include new images and training videos on many special tools as well as updated tool organization and inventory information. (Fig. 10)


Fig 10

Tool Use Images – Over 150 new images are available on the website to help identify the special tools. In addition, by clicking “Search Videos” and selecting a special tool number, a variety of tool instruction training videos can be viewed.


Sales History Upload – To save time assigning existing tools in the dealership, the current GM Special Tool sales history has been uploaded to an account for every dealership. For dealerships not currently using the website, contact SPX for the necessary login information to obtain your uploaded tool history. Using the Tool Location feature, tool storage locations can be assigned for the dealership’s tool inventory to make it easier to find and use the special tools needed for proper repairs.


Tutorial Video – An informative video that guides users through the key functions of the website is available. It explains how each screen of the website can be used to help organize the dealership’s special tool inventory.


Special Tool Information


The website also provides quick access to plenty of special tool information. (Fig. 11) All monthly special tool shipment notices are posted by year/month and a Special Tool list by franchise is updated monthly. In addition, the website includes an electronic catalog of all GM special service tools.


Fig 11

TIP: Never discard older special tools. GM and SPX continuously monitor the entire tool database to determine additional applications for current tools to avoid new tool releases.


To visit the Special Tool Organization website login page, click here.


To obtain a user name and password, contact SPX at 1-800-GM TOOLS or


– Thanks to Russ Dobson

Service Bolts for Camber Adjustment

When performing a wheel alignment on a 2012 Sonic, do not grind the front strut bores for the bolts to allow adjustment of the front camber. There are service bolts available to allow the front camber to be adjusted, if needed.


In order to adjust camber, replace the existing bolt, part number 11610469, that has a 0.05 to 0.35 mm interference fit (no movement) (Fig. 7) with service bolt, part number 11561297, that has a 2 mm clearance and service nut, part number 11516382, (Fig. 8) allowing movement of the strut to change the vehicle’s camber.


 Fig 7

 Fig 9

If unable to adjust the camber to specifications, inspect the vehicle closely and replace any bent or damaged components.


– Thanks to Ernest Haller

New GDS 2 Graphing Compares Multiple Parameters

The graphing capabilities of the Global Diagnostic System 2 (GDS 2) were recently updated. The new software package makes it easier to manipulate and view data, and is available for both live data and stored data.


One of the enhancements included in this update is the ability to overlay graphs in order to compare multiple parameters. (Fig. 6) A new line format provides easy-to-read values. Plus, it allows data to be sorted by parameter ECU or the units.


Fig 6

The overlay feature can be used by simply selecting specific data parameters in the Diagnostic Data Display tab and then clicking the Lock icon. Once the parameters are locked in, they can be displayed as a line graph as well as individual parameters. To view the graphs of individual parameters, click the Graphical Data Display tab. The parameters can be manipulated several ways, including moving the timeline, zooming in and out, and moving the graph data.


In addition, the tool bar functions on the side of the screen can be used to change the settings of the graph. Data of the entire graph or just one parameter can be manipulated. Functions include adding or removing data capture indicators, expanding or condensing the data points, and adding or removing graph gridlines.


To view a demonstration of the new graphing capabilities of GDS 2, check out the February Emerging Issues seminar (10210.03D) on (In Canada, see TAC Talk April 2012.)


– Thanks to Matt Singer

Inside Rearview Mirror Adjustment Points

The inside rearview mirror of the 2013 Malibu features two adjustment points — one at the mirror and one at the windshield. If the mirror is not adjusted properly, the driver’s view through the mirror may be reduced by the headliner or the auto-dimming feature of mirror may not darken automatically due to the photo sensor being shaded by the headliner.


Check the positioning of the inside rearview mirror at both points of adjustment. If the pivot at the windshield is up all the way, when the mirror is adjusted for viewing at the lower pivot, the headliner will be visible in the mirror and will shade the dimmer photo sensor. Adjust the pivot at the windshield downward first (Fig. 5, A), and then position the mirror for the desired viewing angle. (Fig. 5, B)


Fig 5

– Thanks to Christopher Crumb

Trunk Lid Not Opening Completely

On some 2013 Chevrolet Malibu Eco models, the trunk lid may not rise by itself to the full upright position when released. This may be caused by the trunk lift springs being in the wrong position.


Loosen the trunk trim to gain access to the lift springs. Check the position of each spring. Both lift springs should be in the rear-most position in order for the trunk lid to open completely when released. (Fig. 4)


 Fig 4

– Thanks to Christopher Crumb

All-New 2013 Malibu Eco

Fig 1

As the first Chevrolet to feature eAssist electric technology, the all-new 2013 Malibu Eco delivers outstanding fuel efficiency without compromising ride, performance or comfort.


Combined with a 2.4L Ecotec 4-cylinder engine, the eAssist system (RPO HP6) uses a lithium-ion high voltage battery, electric induction motor-generator and regenerative braking to provide added vehicle performance when needed while also enhancing fuel economy.


To be introduced later in the model year in other Malibu models will be an all-new 2.5L 4-cylinder engine.


All Malibu models are based on GM’s Global Architecture (Global A), which requires use of the Global Diagnostic System 2 (GDS 2) and the Multiple Diagnostic Interface (MDI) tool.


eAssist Powertrain


Malibu Eco’s eAssist system is mated to an Ecotec 2.4L direct-injection four-cylinder engine (RPO LUK) and Hydra-Matic 6T40 six-speed automatic transmission (RPO MHH). The lightweight aluminum engine is rated at 182 horsepower and 170 lb.-ft. of torque.


The eAssist system uses power stored in the air-cooled 115V lithium-ion battery to provide needed electrical boost in various driving scenarios. Fuel economy also is increased through:

• Automatic engine start-stop functionality that uses electricity instead of gasoline when stopped

• Aggressive fuel cut-off during deceleration down to zero mph for added fuel savings

• Regenerative braking, which provides up to 15 kW of electricity to charge the lithium-ion battery

• A standard active shutter system located in the lower grille that automatically closes airflow through the lower intake opening when it’s least needed. The shutter is open or closed based on engine coolant temperature and speed

• Four underbody panels that cover approximately 50 percent of the lower portion of the vehicle, providing a cleaner airflow path beneath the vehicle


The induction motor-generator (Fig. 2, A) bolsters the 2.4L 4-cylinder engine (Fig. 2, B) with approximately 11 kW (15 horsepower) of electric power assist during heavy acceleration and 15 kW of regenerative braking power.


The 65 pound (29 kg) lithium-ion battery power pack (Fig. 2, C) is located in a compartment between the rear seat and trunk. An electric fan cools the power pack, drawing air from a vent located in the package tray, behind the rear seat.


 Fig 2

For more information about the operation of the eAssist system, refer to the July 2011 edition of TechLink. [ADD LINK TO JULY 2011 TL EASSIST ARTICLE]


Several eAssist parts are currently on restriction through the GM Technical Assistance Center. Refer to #PIP4920E for more information.


Ride and Handling


The Malibu Eco’s aerodynamically optimized exterior was designed to stand out with an aggressive, substantial appearance. It has a 4.5-inch (114 mm) shorter wheelbase and the 62-inch (1,574 mm) front and rear tracks are more than two inches (51 mm) wider than the model it replaces.


The suspension includes a MacPherson strut front and a multi-link rear setup with aluminum components and a hollow stabilizer bar to reduce unsprung weight.


The braking system has 11.7-inch (297 mm) ventilated front discs and 11.5-inch (292 mm) solid rear discs with aluminum rear calipers.


Chassis control technologies include four-channel anti-lock brakes, full-function traction control, four-corner electronic stability control (StabiliTrak), electronic brake force distribution, brake assist, corner brake control, panic brake assist and drag torque control.


Additional safety features include eight standard air bags — including knee air bags and full-length side curtain air bags — and available rear thorax/pelvis air bags.


Customer Convenience


Inside the Malibu Eco (Fig. 3), the new optional MyLink system uses Bluetooth® or USB to connect a smartphone or other portable device, such as an iPod®, to the 7-inch LED high-resolution touch screen display. System control is enabled via voice activation control and streaming online services like Pandora® Internet Radio and Stitcher SmartRadio® are seamlessly integrated.


 Fig 3

For more information about the MyLink system, refer to the February 2012 edition of TechLink. [ADD LINK TO FEB 2012 TL MYLINK ARTICLE]


In addition to entertainment information, the touch screen also displays climate control operation.


TIP: When the climate control system is turned off, the SYNC (links all settings to the driver’s setting) indicator on the passenger’s temperature control may remain illuminated.


Another available customer convenience feature is the optional heated seats, which can be linked with the remote start feature. In temperatures lower than 45º F (7º C), the heated seats automatically activate during a remote start if enabled through the Vehicle Settings menu.


TIP: The heated seats will turn off after a remote start once the vehicle is started by the driver using the key.


The Malibu Eco is fitted with a 5.4-mm acoustic-laminate windshield and 5-mm acoustic-laminated front door glass, which reduce wind noise by about three decibels when compared to conventional tempered glass. Noise also is reduced by 16 expanding-foam acoustic baffles that are placed in cavities throughout the body structure.


Thanks to these sound-reducing and sound-absorbing components as well as the aero-optimized exterior, the Malibu Eco is the quietest Chevrolet in history.


On upcoming Malibu models without eAssist, pushbutton engine start and passive entry will be available. The Remote Keyless Entry transmitter must be in the vehicle to turn on the ignition.


When programming control modules, the ignition must be in the ignition On, engine Off mode by pressing and holding the Start/Stop button, without pressing the brake pedal, for 10 seconds. The green LED indicator on the button will illuminate. This mode is different from the Accessory mode, in which the Start/Stop button is pressed without the brake pedal depressed.


To operate the passive entry system, the RKE transmitter must be within approximately three feet of the vehicle. Pressing the touchpad on any door handle will unlock the door. Press it again to unlock all doors (depending on Vehicle Settings in the Configuration menu). Pressing the touchpad on a front door handle will immediately lock the vehicle. The ignition must be off, the RKE transmitter out of the vehicle, and all doors closed.


Service Training


To view the training courses covering many of the different Malibu systems, visit (or in Canada).


There are several eAssist-related training courses available, covering safety information, diagnostics and service. Plus, to learn more about the new entertainment system, check out course Entertainment Systems 2, 19047.13W2, which covers Bluetooth functions and features (MyLink) as well as how to identify and diagnose connectivity concerns.


– Thanks to Bob Wittman

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