Wheel and tire assemblies are balanced at the assembly plant, using carefully determined specifications provided by engineering. To maintain the vehicle's designed-in ride and handling characteristics, it may be necessary to balance a wheel and tire assembly after it has been in service for awhile (fig. 1). For instance, after repairing a flat tire.

An out-of-balance wheel and tire assembly is the cause of vibrations, which usually become more severe as road speed increases. Accurate wheel balancing can eliminate or greatly minimize these vibrations, contributing to an improved, smooth ride.

Wheels and tires are balanced and installed to the vehicle as an assembly, and it is not practical to balance either component separately.

Bulletin 07-03-10-017 was recently issued to address a wheel balance condition when using an off-car tire balancer.

TIP: Although this bulletin is specific to the 2008 Malibu with 18-inch cast aluminum wheels, the principles apply to all passenger car wheels.

In some cases, the wheel/tire exhibits vibration at highway speeds even after being balanced. A possible cause is that some cast aluminum wheels may not "chuck up" properly when installed on some wheel balancers. Here's how to avoid problems.

The Cause

Wheel dimensions are all taken from the hub bore (center hole) of the wheel, and that's where the balancer cone must contact when installed from the back side of the wheel.
This is true of both hub-centric and lug-centric wheels.

Some standard wheel balancer cones may not fit the hole properly. The cone may bottom out against the smaller hubcap diameter (A) instead of contacting the center hole surface (B) (fig. 2). If this occurs, the wheel may not be properly centered on the balancer, and the resulting balance is inaccurate.

A  Hubcap diameter

B  Hub bore (center hole)

What To Do

Before installing the cone to the wheel balancer shaft, check the cone for proper fit to the center hole of the wheel (fig. 3). Make sure it does not bottom out. The side of the cone should uniformly contact the center hole. If it bottoms out at the hub cap diameter and is not supported by the hub inside bore, it may rock. Do not use a cone that exhibits these conditions.

TIP: It's easier to trial-fit the cone to the wheel before installation on the balancer.

You can contact Dealer Equipment for proper cone specifications (call 1.800.GMTOOLS).

Mounting the Wheel to the Balancer

As described above, make sure the cone contacts the wheel's center hole without bottoming out. Install the cone to the balancer shaft (fig. 4). Install the wheel to the shaft, install the wing nut and tighten (fig. 5).

TIP: Be sure the wing nut is equipped with a non-marring pressure cup, to avoid cosmetic damage to the wheel face (fig. 6).

Care of Balancer Cones

Balancer cones as well as backing/clamping plates and the screw and arbor on the machine need to be kept free of rust, corrosion, grit and dirt (fig. 7). They must not have physical damage from rough handling. Essentially, these parts should be maintained and cared for at the same level as the centering cones and bell clamps of a brake lathe.
The parts can be cleaned of dirt and minor corrosion. Minor dents and damage can be remedied with a small whetstone. Major damage or corrosion requires replacement of the involved component.

- Thanks to Dick Gratz and Will Godfrey

The GM Service Information (SI) application has recently received a number of enhancements. However, the basic functionality has not changed. You will still be able to use SI to find bulletins, campaigns, PIs, service manuals, owner manuals, unit repair manuals, specialty publications and others.

Perhaps the first thing you'll notice is that throughout SI, the icons have all been replaced with more colorful and easily identified graphics (fig. 8).

Main Page features -- Because SI is used around the globe for North American vehicle content, you have the ability to select your Region (this is GMNA in the United States and Canada) and Language (English, Spanish, French) preferences.

The home page now permits you to enter a vehicle's VIN, or you can specify the year, make and model.

A box in the upper right contains the message of the day. This is where you will see timely and useful information. If there is no message, the box does not appear.

Keyword Search -- You can now search the entire document (full text search) (fig. 9) instead of just the titles, as in the past. You can search in the service manuals, bulletins, owner manuals, labor time guide, etc. The search is limited to the publication you choose; it does not jump to others.

Additionally, there are two types of search. Basic search performs a search on a single word, while advanced search will search a phrase of two words or more. A Search Help link provides details.

Printing features -- You can print a document in any of three ways.

-     File > Print

-     File > Print Preview (recommended for printing a portion of a document)

-     Use print icon from the browser

Other features -- It's easier to isolate an item in a list, because all document lists now display with alternating background shading, and line spacing is 1.5 instead of 1.

If a service category has an associated document, an active link is available. If the service category does not have a document available, the link cannot be selected.

Each page contains a fixed header and a "bread crumb" trail. The fixed header is everything above the Search line. The fixed header allows you to keep the vehicle information displayed at all times. And the bread crumb trail allows you to jump to a previous page without having to use the browser's BACK button.

The Latest News page is now called Search New Bulletins (fig. 10). It defaults to the previous week, and you can specify to view up to 8 weeks of material.

- Thanks to Lisa Scott

There are some important differences when programming a Saturn ASTRA. This is the first in a series of articles that will explain the differences in programming and diagnosing this vehicle.

TECH 2 SOFTWARE DIAGNOSTICS AND PROGRAMMING

IMPORTANT: Before starting programming:

- Be sure that you have Saturn ASTRA Tech 2 Software installed on a dedicated Tech 2 PCMCIA card.

- The 2008 Saturn ASTRA requires the use of a separate Tech 2 software version for diagnostics and Service Programming (SPS). This version contains only support for the ASTRA. Additionally, the North American Tech 2 version will not contain diagnostic/programming support for the ASTRA.

The Saturn ASTRA software can be loaded onto either a 32MB or 10MB Tech 2 flash card. The 10MB cards were used by Saturn retailers when the Tech 2 was first released. Using the 10MB card for the Saturn ASTRA will allow you to keep the N.A. Tech 2 software separate on the 32MB card.

To download the ASTRA Tech 2 Software:

- Go to TIS 2 Web

- Select Tech 2 Software Download (SWDL)

- Once in SWDL, select ‘Custom’ from the ‘Update Mode’ selection then select ‘Next’

- From the ‘Select Applications’ screen, scroll to the English Saturn ASTRA 28.001 folder. Highlight the 28.001 download.

- (DO NOT use the 32MB version. The regular one will work on both 10MB and 32MB cards). Select the right-pointing arrow and Next to download the software.

IMPORTANT: Do not operate the Tech 2 with the 32MB and 10MB cards inserted into the Tech 2 at the same time. You may experience intermittent programming or diagnostic errors when trying to perform functions on the 32MB card. Run the 10MB card separately and always remove the 10MB card when not in use.

SECURITY CODE REQUIRED FOR IMMOBILIZER PROGRAMMING

Certain modules on the Saturn ASTRA use a security code as a means of theft deterrence. Each vehicle is assigned a specific four-digit security code at the time of manufacture.
This security code is used by multiple modules which require a correct security code to operate properly. If a security code is not programmed or a security code which does not match that of the vehicle is used, vehicle starting is disabled. The following modules utilize security code:

- Engine control module (ECM)

- Steering column module (CIM)

- Instrument panel cluster (IPC)

- Underhood electrical center (UEC)

- Rear electrical center (REC)

- Radio Entertainment Head Unit (EHU)

Obtaining the Security Code

Before beginning a programming event for any of these modules, you must first obtain the security code.

The security code can be found in GM DealerWorld under the parts tab and Key Code Look Up. Dealers in Canada can find the security code in the GM Parts Locator and Information Services application. The security code may also be found in the vehicle documentation as a glove box insert.

Key Code Look-Up is restricted to authorized personnel only. Check with your dealership PSC or service manager for access information.

TIS2WEB SECURITY ACCESS PROCEDURE

'Security Access' prevents unauthorized programming of vital functions in vehicles.

Some of the programming functions that use the Tech 2 are inaccessible without the enabling through TIS2Web. Some of the inaccessible programming functions that need 'Security Access' for their performance are:

- Programming of the immobilizer

- Programming of the transponder key

- Radio Entertainment Head Unit (EHU)

After the security programming has been performed the Tech 2 displays the following:

"Get Security Access from TIS2000!”

In order to perform these programming procedures it is necessary to get security access from TIS2Web.

The operation 'Security Access' includes the following steps:

1. Connect Tech 2 with a RS232 cable to the PC.

2. Connect Tech 2 to the vehicle ALDL.

3. From the TIS2Web main screen, select the 'Security Access' icon.

4. Select the connected device.

5. Continue with Next >

6. Validate the Vehicle Identification Number (VIN) read from the device.

7. The request is now processed.

8. The user is being informed of the enabled 'Security Access'.

9. Click Finish to close the application 'Security Access'.

These instructions can also be found in TIS 2 Web under the Help function.

Additional Information Regarding the Use of the Security Access Application

When reprogramming a control module which has already been programmed, additional security measures must be met before reprogramming is allowed. Before programming, security access must be granted by connecting a Tech 2 in a pass-thru arrangement and requesting security access in TIS. Once security access is granted, the security code must be entered. The security code can be found in DealerWorld. Both of these security measures must be met before the Reset ECU selection is allowed.

- Thanks to Mike Waszczenko and Reuben Gosewisch

This information applies to C/K trucks with diesel engines. In some cases, the exhaust pipe is replaced in response to a customer comment of poor engine performance or high fuel consumption, on the assumption that visible depressions in the exhaust pipe are damage that has increased exhaust backpressure.

The exhaust pipes installed at the assembly plant contain depressions that are put there by design, to provide clearance for assembly tooling. Service replacement parts do not contain these depressions because they are not necessary for service replacement.

Exhaust backpressure is minimally affected by the clearance depressions, and service parts without the depressions are not superior to the production parts.

DO NOT replace the tail pipe when these design-intent depressions are the only finding.

- Thanks to Doug Ritter

According to PIT4459B, some owners of a 2008 Colorado or Canyon may comment that the vehicle has poor or no Remote Keyless Entry (RKE) range at times especially when exiting the vehicle after turning the engine off. When the vehicle is turned off, sometimes the OnStar module does not go to sleep quickly enough and the RKE performance may be negatively affected. The OnStar module may be giving off EMI (Electro Magnetic Interference) that is near the same frequency as the RKE transmitter. The routing of the RKE antenna may be too close to the OnStar module, causing the receiver in the BCM not to receive the RKE transmitter signal.

While duplicating the concern, remove the 10amp OnStar fuse from the UBEC and attempt to duplicate again. With the fuse removed, the RKE functions should work with no intermittent operation or range issues.

TIP: If the concern is still duplicated with the OnStar fuse removed, the following procedure is not needed.

Secure the screws on the case of the OnStar module (VCIM). Secure only the screws shown in the illustration (fig. 11). Typically, a 1/4 turn is sufficient to snug the screws.

Reevaluate the customer concern with the OnStar fuse installed. If the concern is still present, perform the following steps.

Re-route the antenna away from the OnStar module. Follow these steps so the antenna is mounted and secured to the IP brace behind the right HVAC deflector.

1. Access the BCM antenna connector. Trace the antenna wire and loosen from its existing position.

2. Starting from the BCM, route the antenna wire to avoid damage and snap the RKE antenna into the hole on the passenger knee bolster bracket (fig. 12).

3. Route the wire and secure the RKE antenna to IP frame with tape (fig. 13).

4. Snap the RKE antenna into the hole near outer HVAC vent (fig. 14).

5. Be sure the antenna connector is fully seated into the BCM.

- Thanks to Dino Poulos

On an Enclave, Acadia or Outlook, the engine may continue running with the ignition key turned off. This can happen if circuit 5985 (the ignition 1 circuit going to the ECM) has 5 volts or more on it when the ignition key is turned off.

Check circuit 5985 at the ECM for voltage (5 volts or more) with the ignition key turned off.
If voltage is found on circuit 5985, remove the fuse for the BCM and the TCM one at a time, and see if the engine turns off. If the engine does not turn off, and there is still 5 volts or more on circuit 5985, check circuit 5985 for a short to voltage concern. If the engine does turn off when pulling the BCM or TCM fuse, replace the module that caused the engine to turn off with the fuse removed.

- Thanks to Ron Erman

This information applies to all 1998-2007 cars and light duty trucks equipped With 4L60E, 4L65E and 4L70E transmissions RPO M30, M32 and M70.

When a replacement spacer plate is ordered for these vehicles, you may receive a plate with the gaskets bonded to the plate. This plate is a direct replacement for the original spacer plate with removable gaskets.

TIP: If performing a repair that does not require plate replacement (for instance, a transmission overhaul), a gasket will come in the overhaul or gasket kit and can be obtained from GMSPO.

- Thanks to Chuck Krepp

This information applies to 2005-current Cobalt and 2006-current HHR with automatic transmission (fig. 15).

Owners of some of these vehicles may comment that the key cannot be removed from the ignition switch or the transmission shifter cannot be moved out of the Park position.

Customer Tips

Before performing any diagnosis or repairs, be sure the customer understands proper operation of the transmission shifter and BTSI.

The shift lever cannot be moved from the Park position if the button is pressed before the brake is applied.

Also, if the driver attempts to move the shift lever before the BTSI responds, the lever cannot be moved. Be aware that the amount of time required for the BTSI to respond to brake application has been reduced.

TIP: The response time is fixed for each model year and cannot be changed by reprogramming.

The owner manual (page 2-22 in Cobalt and 2-24 in HHR, 2008) explains how to turn off the ignition and remove the key under the heading Column Lock Release.

- Move shifter to Park.

- Remove cover from bottom of steering column.

- Locate and depress the plunger.

- With plunger depressed, turn the ignition to OFF and remove the key.

Shifter Diagnostic Tips

Although the transmission shifter is often suspected of being the cause, there are several things to check first.

TIP: All of these can be checked without test equipment.

1. Do the brake lights work? If not, the brake switch is not working properly.

2. Does the BTSI solenoid release with the ignition on and the brake applied? If the BTSI solenoid is not working properly, the lever cannot be moved from Park.

TIP: You can hear the BTSI solenoid operate, and can feel it with fingers placed lightly on the housing at the base of the shift lever.

3. Check if the key release solenoid in the steering column is operating. With the ignition on, brake not applied, and shifter in Park, depress the button on the shifter. The key release solenoid should operate. If the key release solenoid is not operating, the key cannot be removed.

TIP: You can hear the solenoid operate and can feel it with fingers placed lightly on the steering column housing near the ignition lock.

4. If either the BTSI or key release solenoid does not operate, check the adjustment of the shift cable. If the cable is out of adjustment, the shifter may not be able to be placed fully in the Park position.

Some Conditions Inside the Shifter

Spilled Beverages -- Check to see if beverages have been spilled into the shifter. Beverages are sticky, and can hamper movement of components inside the shifter housing. A customer may have wiped up the easily visible residue (fig. 16), but you can pry off the bezel to look at the top of the shifter housing (fig. 17, 18, 19). With a light, you can peek inside to see if there is liquid on the corrugated strip or in the base of the shifter housing.

TIP: There is a small fiber washer on the shaft of the BTSI solenoid that is in a direct line below the edge of the housing. If liquid is spilled onto this washer, it may become saturated.

In a normal system, the fiber washer moves along with the shaft (fig. 20). If it has become saturated with beverage, the fiber washer sticks to the solenoid (fig. 21), creating a drag on the shaft, possibly preventing motion.

TIP: You can use a dental mirror to inspect the fiber washer (fig. 22).

Redesigned Shifter -- A redesigned shifter was put into production on October 2, 2006 on the HHR and the Cobalt.

When the button on the shifter is pressed, a plunger moves downward inside the shaft.
A metal detent pin at right angle to the plunger signals the BCM that the shift lever is in the Park position. If the pin hole in the plunger becomes worn, the pin can tilt in the plunger
(fig. 23). When tilted, the pin may fail to contact the microswitch which signals the BCM that the transmission is in Park (fig. 24). Without this signal, the ignition key cannot be removed.

The redesigned shifter has a metal slug between the upper and lower portions of the plunger (fig. 25), providing a more robust installation for the detent pin. This ensures that
the pin makes contact with the microswitch (fig. 26).

- Thanks to Wayne Zigler

The front seat back trim on the 2007-08 Outlook and Acadia and 2008 Enclave is retained by two spring retainer clips at the top and two tabs at the bottom. Here are some tips on how to avoid damage during removal of the trim.

Insert a flat-blade tool from the side (fig. 27) and push inward on one of the top retainer clips to release the panel, while pulling rearward at the top of the panel. Repeat on the opposite side.

TIP: The clip has a notch for placement of the flat-blade tool (fig. 28).

Lift the panel upward to detach the bottom tabs, and remove from the seat.

- Thanks to Gary McAdam

This information applies to 2004-07 Colorado and Canyon and 2006-07 Hummer H3 with any of the following engines:

- 2.8L (VIN 8 - RPO LK5)

- 2.9L (VIN 9 - RPO LLV)

- 3.5L (VIN 6 - RPO L52)

- 3.7L (VIN E - RPO LLR)

An intermittent SES light and reduced engine power mode may be experienced with any of the following DTCs: P060E, P1516, P2135, and/or P2138. If two or more of these DTCs are present, this is most likely the result of low battery voltage when the engine is cranking.

If the SI diagnostics do not isolate the cause of this concern, test the battery following the latest version of 02-06-03-009, and recharge or replace the battery as indicated on the tester. If the tester indicates Good Battery, check for an excessive parasitic draw and for proper charging system operation, and repair as necessary. If there is no problem found after following these suggestions, fully charge the battery and re-evaluate the concern.

- Thanks to Jamie Parkhurst

On a Malibu, Vue Greenline or Aura Greenline Hybrid with 2.4L Engine (VIN 5 or Z - RPO LAT), an intermittent battery light may be experienced with any of the following DTCs: P0AFB, U0111, and/or U1897. Typically, this concern is very intermittent, so it is unlikely that it will be verified while the vehicle is at the dealership.

If this concern is experienced, perform the SI diagnostics and review the latest versions of PIP4248 (U0111 and U1897 after ECM Reflash) and PIP4288 (U0111 and U1897 after 07141 BECM Reprogram) to determine if they apply to the vehicle and concern that you are working on. If the SI diagnostics do not isolate the cause of this concern and PIP4248 and PIP4288 do not apply to the vehicle or concern that you are working on, replace the BDU (Battery Disconnect Unit), otherwise known as the BECM (Battery Energy Control Module), and re-evaluate the concern.

- Thanks to Jamie Parkhurst

2009 Pontiac Vibe vehicles are shipped with the white unmarked connector link disconnected from the underhood fuse block. The white link is stored in a spare fuse holder (shipping location) in the underhood fuse block. To operate the radio, OnStar, dome lamp, remote keyless entry and/or power door locks properly, the white link must be removed from the spare location and installed into the short DCC fuse cavity (fig. 29).

A  Shipping location

B  Short DCC location

- Thanks to Al Ferry

Some owners of a 2005-08 Corvette or XLR may comment of an occasional No Fob Detected message on the DIC display when the fob is located somewhere on the driver's seat. They also may comment that the fob reminder (3 horn honks) is heard when exiting the vehicle with the key fob. This is because the original RCDLR software does not adequately cover the driver's seat and it can also detect the fob when it is slightly outside of the driver's door. New software will add a new zone to better cover the driver's seat, and it will also add a 2 second delay after the door closes before checking for the fob on the interior. This affects all vehicles built before October 2007.

IMPORTANT: Before programming, the radio and HVAC fuses MUST be removed and the ignition must be in Key On Engine Off mode. The radio and HVAC fuses are located in the BCM fuse block on the passenger floor electrical center. One of the fuses is labeled RDO/S'BAND/VICS and the other is labeled HVAC/PWR SND.

Program the RCDLR with revised software using the TIS2Web PassThru method. When programming, it is necessary to select Replace and Reprogram ECU.

If the programming phase does not finish successfully and the RCDLR appears to be in a locked-up state, do not turn off the ignition. The RCDLR can be reset by removing fuse 11 in the UBEC for 30 seconds. Reinstall the fuse.

Be sure the radio and HVAC fuses are pulled. Attempt programming the module again.

If the ignition was turned to OFF after the locked-up condition occurred, it's possible to continue programming. Simply add the VIN manually in TIS.

TIP: Do not replace the module -- just reprogram it. Also fob programming and TPM Learn are not required.

- Thanks to Dino Poulos

An article in the January 2008 TechLink explained how to deal with a sunroof that stops and auto-reverses direction instead of opening or closing. According to bulletin 06-08-67-011D, replacing the drive motor with a high current version may be necessary. A new motor went into SRX production during the start of the 2007 model year. This motor has a calibration number of 13 06. It may not be necessary to replace the motor.

IMPORTANT: Before replacing the drive motor, check the calibration number on the motor label (fig. 30). If the motor in the vehicle has calibration number 13 06, do not replace the motor.

- Thanks to Jeff Strausser