The available EN-49228 Laser Belt Alignment Tool is simple to use and time-saving (fig. 1). Use it to assist in achieving precise alignment of the drive belt pulleys. Using it removes the guesswork from proper pulley alignment and may serve to reduce comebacks from:

- Drive belt noise

- Accelerated drive belt wear

- Drive belt slippage

INSTRUCTIONS

TIP: These instructions from bulletin 08-06-01-008 are specific to the truck Gen IV V-8 family of engines. Universal instructions are included in the kit.

CAUTION:

- Do not look directly into the beam projected from the laser.

- Use caution when shining the laser on highly polished or reflective surfaces. Laser safety glasses help reduce laser beam glare in many circumstances.

- Always use laser safety glasses when using the laser. Laser safety glasses are not designed to protect eyes from direct laser exposure.

1. Observe and mark the serpentine belt orientation.

2. Remove the serpentine belt from the accessory drive system.

3. Install the tool onto the power steering pulley. Position the legs of the tool into the outer grooves of the pulley, farthest from the front of the engine.

4. Install the retaining cord around the pulley and to the legs of the tool.

5. Put on the laser safety glasses provided with the tool.

6. Depress the switch on the rear of the tool to activate the light beam.

7. Rotate the power steering pulley as required to project the laser beam onto the crankshaft balancer pulley grooves (fig. 2).

8. Inspect for proper power steering pulley alignment.

- If the laser beam projects onto the second rib or raised area, the pulleys are aligned properly.

- If the laser beam projects more than one-quarter rib 0.9 mm (0.035 in) mis-alignment, adjust the position of the power steering pulley as required.

- Refer to SI for Power Steering Pulley Removal and Installation procedures.

9. Install the serpentine belt to the accessory drive system in the original orientation.

10. Operate the vehicle and verify that the belt noise concern is no longer present.

PARTS INFORMATION

Contact 1-800-GM-TOOLS or http://gmspecialservicetools.spx.com for information or to order this tool.

- Thanks to Ron Minoletti

Effective May 1, 2008, changes have been implemented which will enable TAC to provide more timely and consistent service.

A most important requirement is that technicians MUST complete the key steps of Strategy Based Diagnosis (SBD) BEFORE placing the call to TAC. This information will be REQUIRED at the time of the call:

1. Complete work order, including VIN and details of customer concern.

2. Amount of days the vehicle has been down.

3. Attempt to duplicate customer concern.

4. All DTCs, values and measurements recorded and diagnosed.

5. Search all of SI for diagnostic information, bulletins, and PIs.

IMPORTANT: If you are not prepared at the time of the call, you will be requested to use SBD before calling back.

TIP: For more information, refer to these preparedness documents:

- Policy and Procedures, section 5.3.1

- SI Document 1957622, Strategy Based Diagnosis

- Bulletin 01-00-89-010G, Use of Customer Concern Verification Sheets, Comeback Prevention, GM TAC Form, Strategy Based Diagnosis (SBD), Intermittent Concerns Diagnostics, Repeat Repair Log

- Thanks to Ward Boyer and Ann Briedis

Loss-of-communication U-codes can set for a variety of reasons. Many times, they’re transparent to the vehicle operator and technician, and/or have no associated symptoms. They will eventually erase themselves automatically after a number of fault-free ignition cycles. Sometimes, while diagnosing a specific customer concern or after a repair, you may notice a history U-code present. However, there is no associated “current” or “active” status. Additionally, a loss-of-communication U-code does not typically represent a failure of the module that set it. The most likely scenario of this condition would be attributed to:

- A control module on the data communication circuit was disconnected while the communication circuit is awake

- Power to one or more modules was interrupted during diagnosis

- A low battery condition was present, so some control modules stop communicating when battery voltage drops below a certain threshold

- Battery power was restored to the vehicle and all control modules on the communication circuit did not re-initialize at the same time

If a loss of communication U-code appears in history for no apparent reason, it is most likely associated to the scenarios above. These are all temporary conditions and should never be interpreted as an intermittent fault causing part replacement.

TIP: A loss-of-communication U-code does not typically represent a failure of the module that set it.

It’s important to remember that all “current” or “active” DTCs need to be diagnosed and repaired by following proper service procedures. Always remember to clear all DTCs after successfully diagnosing and repairing a customer concern.

- Thanks to Paul Gallo

Many electrical centers (also called Bussed Electrical Centers or BECs) (fig. 3) use Printed Circuit Board (PCB) relays. The PCB relay is integrally soldered to the printed circuit board; it is not plugged in (fig. 4).

Because the PCB relay is compact, it helps electrical engineers reduce the size and mass of the BEC.

In the past, you could either feel or hear the "click" of an older style relay, as you operated the circuit it was controlling. You could often use a scan tool or operate the circuit to verify that the relay was operating.

Due to the location and size of the PCB relays, it may not be possible to hear or feel them operate, so another method has been developed to diagnose them.

The component technical specification (CTS) of the BEC requires that if a fuse is used with a relay, the fuse must be downstream of the switched contacts of the relay.

Depending on the operation of the circuit, the relay contacts will open or close, and voltage will be either present or not present at the fuse. A test lamp can be used to verify this change by touching the small metal portion on top of the fuse (fig. 5).

If the circuit is protected in some way other than with a fuse, a test point is placed in the
BEC for use with a test lamp (fig. 6). The test point is called out on the BEC cover (fig. 7)
and in SI. Test procedures are written to use either the fuse or test point as a diagnostic location.

TIP: If necessary, carefully move the test lamp probe around in the opening to get a good connection with the test point.

TIP: Using the prescribed fuse or test point as a diagnostic location, it is possible to diagnose the operation of PCB relays without removing the BEC from its mounting place.

- Thanks to John Roberts

Bulletin 08-08-50-007 is being published to explain how to properly remove the driver
or passenger seat back cushion finish panel/cover from the front seat of the 2006–08 Hummer H3.

Release the two upper spring type clips, followed by the two side clips, then the lower bottom retaining hooks.

1. Push the trim cover forward at the upper right corner with your hand.

2. Insert a trim tool on top of the clip and push down on it to release the spring-type clip from the frame (fig. 8). Repeat for the other side.

3. Once the two upper corners are released, grab each side of the back panel and pull outward to release the side clips.

4. Place one hand at each bottom corner of the back panel (between the panel and trim), press in and pull upward to release the bottom retaining hooks.

- Thanks to Terry Nicholas

For the 2009 model year, the way in which parking assist notifies the driver of an object
of interest has been modified. This change applies only to the Buick Enclave, Cadillac Escalade, Chevrolet Tahoe, Silverado, and Suburban, GMC Acadia, Sierra, Yukon, and Yukon XL, and Saturn Outlook.

TIP: The new driver notification scheme will be available through a calibration update to previous model year Buick Enclave, Cadillac Escalade, Chevrolet Tahoe, Silverado, and Suburban, GMC Acadia, Sierra, Yukon, and Yukon XL, and Saturn Outlook. The Buick Lucerne and Cadillac CTS, DTS, and SRX will receive a similar calibration update at a later time.

The previous driver notification scheme indicated an object of interest with a single beep at the time of first detection. The system would then continuously beep when the object was within 30 cm (1 ft.) of the vehicle. The new driver notification scheme still indicates an object of interest with a single beep at the time of first detection, but will beep continuously when the object is within 60 cm (2 ft.) of the vehicle. The visual indicators remain unchanged.

Additionally, the 2009 Buick Lucerne and Cadillac DTS will use a new part number sensor and module for the parking assist system. These new parts are specific to the 2009 model vehicles. Do not attempt to service 2009 vehicles with a 2008 part.

Parking Assist Diagnostic Aids

When diagnosing a customer concern on the parking assist system, be aware that certain conditions will normally disable the system. Items attached to the vehicle, such as a trailer hitch receiver or a bike rack, will disable the system because the vehicle cannot distinguish the difference between the items attached to the vehicle and an object of interest. The system will also be disabled if snow, mud, or ice is built up on the sensors or the vehicle travels too fast in reverse. Certain outside influences can also disable the system. Noises which vibrate the fascia, such as a jackhammer or large truck air brakes, may disturb the sensor, causing the system to disable.

As an aid to diagnosis, the scan tool Park Assist Disable History parameters can be used to locate any common causes or trends. For example, if the Park Assist Disable History parameters indicate repeated system disable due to an Attached Object, which could be a hitch receiver, system operation should be discussed with the customer before attempting to diagnose.

The parking assist sensor diagnostics have also been revised in SI. The diagnostic strategy advises that if only a single sensor DTC is present, swap that sensor with another sensor in the fascia to determine if the DTC follows the sensor. If the DTC follows the sensor to the new location, the sensor is likely the cause. If the DTC remains at the original location, vehicle wiring or the object alarm module is likely the cause.

During a system malfunction, it is highly improbable that all of the sensors or all of the sensors and the object alarm module are at fault and require replacement. Further system diagnostics should be performed to determine the specific item causing the malfunction.

TIP: When replacing a sensor, be sure the sensor has corrected the concern before applying paint to the sensor. When painting the sensor, do not apply an excessive amount of paint. High paint thickness may cause a sensor malfunction and system disable.

When servicing the parking assist system, follow standard GM guidelines when documenting the cause and correction on the repair order. Be sure to document all FTBs associated with any DTC(s) that have set.

- Thanks to Mike Gastmeier

On the Acadia, Outlook and Enclave, the quarter trim panel has hidden screw fasteners above the speaker grille and below the armrest (fig. 9) that must be removed before attempting to remove the panel. If the screws are not removed, the panel will crack in the area around the fastener location.

The location of the fasteners can be found in SI document 1903783 for Acadia and Outlook and 1899889 for the Enclave.

- Thanks to Gary McAdam

At Pre-Delivery Inspection of a 2008 Impala, Grand Prix, LaCrosse or Allure, some technicians may note that the ambient temperature display is not accurate.

The ambient temperature display uses an algorithm that delays updating the temperature display unless certain conditions are met, such as driving the vehicle at a certain speed.
This is done to ensure that the ambient sensor does not detect engine heat while the vehicle is idling, which would result in an inaccurate ambient temperature reading.

Don't replace the ambient temperature sensor.

Ensure that the ambient temperature display has updated using the accompanying tables.
It is recommended that the vehicle be driven to update the ambient temperature display. However, if one of the methods is used to update the temperature instantly, be aware that if the engine is idling, the ambient temperature sensor may detect engine heat, resulting in an artificially high reading.

- Thanks to Chris Anderson

2008 Impala

2008 LaCrosse, Allure and Grand Prix

Here's a tip for removing the driver airbag (DAB) from a 2008 Malibu.

Obtain a 9/64-inch T-handle Allen wrench with a blunt end (fig. 10). Use a bench grinder to machine a groove into the end of the tool

A  Radius about 2 mm

TIP: The groove in the tip should be parallel to the T-handle.

Align the tool handle parallel to the steering wheel rim (which places the groove parallel to the spring) (fig. 11). Engage the tool with the DAB spring (fig. 12). The groove helps the tip of the tool remain engaged with the spring. You will feel resistance from the spring.

Place your fingers under the DAB cover at the top edge, about an inch from the switch bezel.

Depress the spring about 5 mm and pull the DAB cover away from the steering wheel
(fig. 13).

- Thanks to Ali Elhadi and Will Godfrey

The overhead Rear Seat Entertainment (RSE) display is an OEM DVD screen (fig. 14) that displays images from the DVD player located in the vehicle’s radio. The DVD player is integrated into the radio and sends visual images to the overhead RSE display. The RSE display may be prematurely replaced due to misdiagnosis of the system. Here are some reasons that have been identified for these misdiagnoses.

TIP: There is also an SPO headrest DVD system available as a dealer-installed accessory. This sytem is independent of the factory-installed overhead system. Refer to SI documents for diagnosis and repair of the headrest system.

Audio with no video present

This condition is referred to as half-play. Half-play and detailed diagnosis are explained in bulletin 07-08-44-018, document ID 2006238.

Half-play occurs when the customer is watching a DVD and exits the vehicle. At the next key cycle, the DVD player (in the radio) begins to play the DVD, but the screen remains off or does not automatically come on. The RSE remote control should be used to turn on the RSE display. If the RSE display does not turn on after using the remote control, proceed with the diagnosis of the RSE system.

Other relevant bulletins are listed in the accompanying table.

RSE display blank or Inop

A blank or Inop RSE display is the most common customer concern for the RSE display. If the RSE display does not have all the necessary signals from the radio, it may not turn ON.

When diagnosing a blank or inop RSE display, refer to the RSE display service information, documents, bulletins, and PIs (Preliminary Information).

Relevant bulletins are listed in the accompanying table.

DVD player does not work

The DVD player is integrated into the radio and separate from the DVD screen. It should be diagnosed separately. The previous RSE system consisted of a DVD player and display integrated into the overhead console. These two components are separate in the present RSE system. Diagnosis of this issue should begin at the radio, because the RSE screen just displays what the radio sends it.

Remember -- the RSE screen and DVD player are separate components and should be diagnosed as such.

Other issues and concerns

Cracks, lines across the display and distorted images are other customer concerns which have been identified through the warranty return process.

Cracks in the RSE display may be caused by an interference of the two forward screws and the LCD. Steps have been taken to eliminate the cause in the assembly plant.

If there is a mark or gouge in the LCD, be sure the cause is not customer abuse.

Do not attempt to repair a RSE display with a broken latch. Replace the display.

Excessive movement in the screen occurs when the screen is opened past the built-in stops. The metal bracket inside the housing where the screen pivots is bent as a result of being opened past the built-in stops.

If there is physical damage to the plastic housing around the LCD display, be sure the cause is not customer abuse.

Improper use of labor codes for the GM SPO Headrest DVD systems.

There are separate labor codes for dealer installed GM accessories. The service manual has updated labor codes for dealer installed GM accessories.

The bulletin number is: 02-00-89-014C (document ID 2039059).

The labor code for the SPO Headrest DVD system is R9392. GM does not release an OEM Headrest DVD system, so all headrest systems should use this labor operation code.

The labor code to use for the overhead RSE display is R5554. Part number restrictions have been put in place for warranty claims against R5554. If the part number is not on the list of acceptable part numbers, the claim will be rejected. Be sure the correct labor operation code is used for the system being repaired.

- Thanks to Greg Rouse, Dean Matoski, Tom Hanselman and Katul Patel

On a 2007-08 Saab 9-3 or 2006-08 Saab 9-5, a customer may comment that the steering wheel control (SWC) button for Talk/Voice Recognition/OnStar is inoperative.

The SWC for Onstar/Voice Recognition is operational only if the vehicle has the BTR Navigation option. Engineering is working to develop software to include all "black tie" radios.

When the software is released, an updated PI will reflect the change. Until then, this is considered normal operation.

- Thanks to Jeff Gorenflo

This information applies to the 2006-07 Rainier, and 2006-08 TrailBlazer, Envoy and 9-7X.

There may be a squeak/squeal noise from the steering column upon initial rotation of the steering wheel, either with the engine running or turned off. The noise is present if the intermediate shaft is disconnected for testing purposes. The source of this noise may be an interference contact between the 48 way harness connector bracket and the SWPS (Steering Wheel Position Sensor) and harness connector housing.

1. Remove the 48 way harness connector bracket (fig. 15).

2. Remove approximately 2/3 of the center rib material to make it flush with the bracket
(fig. 16).

A  Bracket center rib

B  Rib removed

TIP: DO NOT remove the entire rib.

3. Reinstall bracket and check for clearance between the SWPS connector/sensor and the 48 way connector bracket (fig. 17).

A  Check for clearance

4. If additional clearance is needed, turn the bracket over and remove approximately 1 mm of additional bracket material (fig. 18).

A  Remove additional 1 mm

Reassemble and check for clearance as described in step 3. If clearance was adequate,
no further modification to the bracket is necessary. Reassemble the vehicle and test drive
to verify this noise has been eliminated.

- Thanks to Dino Poulos

According to bulletin 08-08-43-007, on a 2008 Colorado or Canyon, the windshield wipers may intermittently wipe without being commanded to operate. This condition may occur at start up or while driving the vehicle.

This condition may be caused by electrical noise that causes the Body Control Module (BCM) to activate the windshield wipers.

Reprogram the BCM. Do not replace the wiper motor, BCM or multifunction switch.

A revised calibration has been developed to address this condition. Reprogram the BCM with the latest software available on TIS2WEB. Refer to the Service Programming System (SPS) and Body Control Module Programming and Setup procedures in SI for additional information. Be sure your Tech 2 is updated with the latest software version.

- Thanks to Dan Oden

On some 2004-08 Cadillac XLR and V models, the Driver Information Center (DIC) may display a "Shift To Park" message when the vehicle is in Park, or the Auto Door Lock/Unlock features may be inoperative. Also, the ignition mode switch may not go to the Off position.

One of these may be the cause.

1. Improperly adjusted shifter cable -- Adjust the shift cable in the Park position. Place the shifter in the Park position, lift the vehicle and rotate the rear wheels to verify that the park pawl is engaged (wheels will not move). Release the cable adjustment lock and allow the cable to relax. Re-seat the cable adjustment lock. Refer to SI document 927794 if needed to verify shift cable adjustment procedures.

2. Secondary park switch circuit concern -- Check the status of the Internal Mode Switch in the Transmission Control Module (TCM). If the TCM is indicating the correct gear, check the secondary park switch located on the right side of the shifter assembly. This switch is a direct input into the Body Control Module (BCM). This data can be viewed by following the Tech 2 path below.

3. Secondary park switch concern -- If the secondary park switch shows Park via Tech 2 data, re-check the shift cable adjustment and make sure the shifter button is not stuck. If both items check OK, replace the shifter assembly. At present, the switch is not available separately.

- Thanks to Dino Poulos