Product Safety - Unwanted ABS Activation

THIS BULLETIN IS BEING REVISED TO ADVISE DEALERS TO ORDER PARTS, IF NECESSARY, FROM GMSPO RATHER THAN THE PQC.

THIS BULLETIN CANCELS AND REPLACES BULLETIN 04030, ISSUED JUNE 2004. PLEASE DISCARD ALL COPIES OF BULLETIN 04030.

General Motors has decided that a defect which relates to motor vehicle safety exists in certain 2004 Chevrolet Malibu and Malibu Maxx vehicles equipped with anti-lock brake system (ABS). The ABS controller may calculate a higher than actual vehicle speed if there is an erratic rear-wheel speed sensor signal. This can cause ABS activation where it is not needed or cause needed ABS activation to be extended during braking as the vehicle speed drops to about 5 km/h (3 mph). A four wheel ABS activation could occur for a maximum of 1.25 seconds on a level surface or for up to 2.5 seconds if the vehicle is on a grade, resulting in increased stopping distances of up to 3.4 m (11.4 ft). If this condition occurs where stopping distance is limited, a crash could occur.

Some customers may experience illumination of the ABS warning lamp on the instrument panel. That can occur when the system detects the erratic speed signals and it means that the ABS is disabled. The brake system will perform normally in non-ABS mode until the vehicle is restarted and the ABS lamp is off.

Dealers are to reprogram the ABS controller.

Involved are certain 2004 Chevrolet Malibu and Malibu Maxx vehicles equipped with ABS and built within these VIN breakpoints:

Important: Dealers should confirm vehicle eligibility through GMVIS (GM Vehicle Inquiry System) before beginning recall repairs. [Not all vehicles within the above breakpoints may be involved.]

For US

For dealers with involved vehicles, a Campaign Initiation Detail Report containing the complete Vehicle Identification Number, customer name and address data has been prepared and will be loaded to the GM DealerWorld, Recall Information website. Dealers that have no involved vehicles currently assigned will not have a report available in GM DealerWorld.

For Canada

For dealers with involved vehicles, a Campaign Initiation Detail Report containing the complete Vehicle Identification Number, customer name and address data has been prepared, and is being furnished to involved dealers. Dealers that have no involved vehicles currently assigned, will not receive a report with the recall bulletin.

The Campaign Initiation Detail Report may contain customer names and addresses obtained from Motor Vehicle Registration Records. The use of such motor vehicle registration data for any other purpose is a violation of law in several states/provinces/countries. Accordingly, you are urged to limit the use of this report to the follow-up necessary to complete this program.

Parts required to complete this recall are to be obtained from General Motors Service Parts Operations (GMSPO). Please refer to your "involved vehicles listing" before ordering parts. Normal orders should be placed on a DRO = Daily Replenishment Order. In an emergency situation, parts should be ordered on a CSO = Customer Special Order.

The following procedure provides instructions for retrieving specific diagnostic trouble codes (DTCs) and reprogramming the ABS module with new software. If specific ABS DTCs are found, one or both rear wheel bearing assemblies will need to be replaced.

Important: In order to perform the following procedure, your Tech 2 must be updated with software version 24.001 or later, CD or TIS application 4.0. If your Tech 2 does not have the necessary software, you will need to update it before proceeding.

1. Turn the ignition switch to the ON position.

Important: In order to perform the following procedure, the diagnostic interface module (CANdi) must be connected between the Tech 2 and the vehicle. Failure to use the CANdi module will result in failure of the Tech 2 to communicate with the necessary module on the vehicle.

2. Connect a Tech 2 (scan tool) and the CANdi module to the vehicle's diagnostic link connector (DLC), power it up and press ENTER.

Important: Before reprogramming the ABS module, you must retrieve and record the occurrence of ABS DTC C0045 and/or C0050 AND the 2-character symptom byte that follows the DTC . Codes will automatically be erased during the reprogramming.

3. Select DIAGNOSTICS and retrieve any current or stored ABS DTC C0045 and/or C0050 AND the 2-character symptom byte following the DTC. Record these DTC and symptom bytes on the vehicle repair order.

If ABS CTS C0045 is found, the LEFT REAR wheel bearing assembly must be replaced. If ABS DTC C0050 is found, the RIGHT REAR wheel bearing must be replaced. Proceed to the next step and perform the Service Programming. After programming is complete, proceed to the section titled, "Rear Wheel Bearing Replacement."

Important: During the service reprogramming in the next step, DTC U2127 may be set in the body control module (BCM) and P1626 in the powertrain control module (PCM). These codes must be cleared immediately following the reprogramming. In addition, the IBCM 1 (30 amp) fuse located in the underhood electrical center must be removed for 10 seconds and then reinstalled. Failure to remove and reinstall this fuse will result in the HVAC system not functioning.

4. Select SERVICE REPROGRAMMING.
5. Follow the on-screen instructions and prompts. If necessary, refer to up-to-date Techline Equipment Users Instructions.
6. Clear any DTCs set during the reprogramming.
7. Press the EXIT key as necessary and disconnect the Tech 2 and CANdi module from the vehicle.
8. Open the hood.
9. Remove the battery cover and fuse cover.
10. Remove the IBCM 1 fuse (30 amp) for 10 seconds and then reinstall.
11. Install the fuse cover and battery cover.
12. Close the hood.

Rear Wheel Bearing Replacement

Important: The following procedure should only be performed if ABS DTC C0045 and/or C0050 were found earlier in the procedure.

1. Raise the vehicle on a suitable hoist and support as necessary.
2. If ABS DTC C0045 was found, remove the LEFT REAR tire and wheel assembly. If ABS DTC C0050 was found, remove the RIGHT REAR tire and wheel assembly. If both ABS DTCs were found, remove both rear tire and wheel assemblies.



3. Remove the two bolts (2) attaching the brake caliper mounting bracket to the knuckle.

Notice: Support the brake caliper with heavy mechanic's wire, or equivalent, whenever it is separated from its mount and they hydraulic flexible brake hose is still connected. Failure to support the caliper in this manner will cause the flexible brake hose to bear the weight of the caliper, which may cause damage to the brake hose and in turn may cause a brake fluid leak.

Important: DO NOT disconnect the hydraulic brake flexible hose from the caliper.

4. Remove the rear brake caliper mounting bracket and caliper as an assembly and support the assembly with heavy mechanic's wire, or equivalent.
5. Remove the brake rotor. Do not force the rotor off. If the rotor is difficult to remove, ease if off by gently rotating it as you pull outward.
6. Disconnect the electrical connector for the wheel speed sensor on the bearing hub.
7. Remove the four nuts attaching the bearing hub assembly to the knuckle and remove the bearing hub and brake backing plate.
8. Position the brake backing plate and new bearing hub assembly to the knuckle and install the four nuts.

Tighten
Tighten the four nuts to 63 N·m (46 lb ft).

9. Connect the electrical connector to the wheel speed sensor on the bearing hub.
10. Thoroughly clean any rust or corrosion from the mating/mounting surface on the backside of the brake rotor. Verify that there are no foreign particles or debris remaining.
11. Install the brake rotor on the bearing hub flange.
12. Install the rear brake caliper and mounting bracket on the knuckle.
13. Install the two bolts.

Tighten
Tighten the two bolts to 115 N·m (85 lb ft).

14. Install the rear tire and wheel assembly. Install the wheel nuts.

Tighten
Tighten the wheel nuts to 140 N·m (103 lb ft).

15. If necessary, perform Steps 3-14 on the other wheel bearing assembly.
16. Lower the vehicle.
17. Pump the brake pedal 2-3 times in order to seat the rear disc brake pads to the rotor.

The General Motors Courtesy Transportation program is intended to minimize customer inconvenience when a vehicle requires a repair that is covered by the New Vehicle Limited Warranty. The availability of courtesy transportation to customers whose vehicles are within the warranty coverage period and involved in a product recall is very important in maintaining customer satisfaction. Dealers are to ensure that these customers understand that shuttle service or some other form of courtesy transportation is available and will be provided at no charge. Dealers should refer to the General Motors Service Policies and Procedures Manual for Courtesy Transportation guidelines.

Submit a Product Recall Claim with the information indicated below:

Note: Canadian dealers should refer to the Canadian distribution of the bulletin for detailed claim information.

Refer to the General Motors WINS Claims Processing Manual for details on Product Recall Claim Submission.

General Motors will notify customers of this recall on their vehicle (see copy of customer letter included with this bulletin).

The US National Traffic and Motor Vehicle Safety Act provides that each vehicle which is subject to a recall of this type must be adequately repaired within a reasonable time after the customer has tendered it for repair. A failure to repair within sixty days after tender of a vehicle is prima facie evidence of failure to repair within a reasonable time. If the condition is not adequately repaired within a reasonable time, the customer may be entitled to an identical or reasonably equivalent vehicle at no charge or to a refund of the purchase price less a reasonable allowance for depreciation. To avoid having to provide these burdensome remedies, every effort must be made to promptly schedule an appointment with each customer and to repair their vehicle as soon as possible. In the recall notification letters, customers are told how to contact the US National Highway Traffic Safety Administration if the recall is not completed within a reasonable time.

All unsold new vehicles in dealers' possession and subject to this recall MUST be held and inspected/repaired per the service procedure of this recall bulletin BEFORE customers take possession of these vehicles.

Dealers are to service all vehicles subject to this recall at no charge to customers, regardless of mileage, age of vehicle, or ownership, from this time forward.

Customers who have recently purchased vehicles sold from your vehicle inventory, and for which there is no customer information indicated on the dealer listing, are to be contacted by the dealer. Arrangements are to be made to make the required correction according to the instructions contained in this bulletin. A copy of the customer letter is provided in this bulletin for your use in contacting customers. Recall follow-up cards should not be used for this purpose, since the customer may not as yet have received the notification letter.

In summary, whenever a vehicle subject to this recall enters your vehicle inventory, or is in your dealership for service in the future, please take the steps necessary to be sure the recall correction has been made before selling or releasing the vehicle.

Dear General Motors Customer:

This notice is sent to you in accordance with the requirements of the National Traffic and Motor Vehicle Safety Act. Federal regulation requires that any vehicle lessor receiving this recall notice must forward a copy of this notice to the lessee within ten days.

General Motors has decided that a defect which relates to motor vehicle safety exists in certain 2004 Chevrolet Malibu and Malibu Maxx vehicles equipped with anti-lock brake system (ABS). The ABS controller may calculate a higher than actual vehicle speed if there is an erratic rear-wheel speed sensor signal. This can cause ABS activation where it is not needed or cause needed ABS activation to be extended during braking as the vehicle speed drops to about 5 km/h (3 mph). A four wheel ABS activation could occur for a maximum of 1.25 seconds on a level surface or for up to 2.5 seconds if the vehicle is on a grade, resulting in increased stopping distances of up to 3.4 m (11.4 ft). If this condition occurs where stopping distance is limited, a crash could occur.

On some vehicles, the ABS warning lamp on the instrument panel may illuminate. This can occur when the system detects the erratic speed signals and it means that the ABS is disabled. The brake system will perform normally in non-ABS mode until the vehicle is restarted and the ABS lamp is off.

Your GM dealer will reprogram the ABS controller and, if necessary, replace one or both rear wheel bearnig assemblies. This service will be performed for you at no charge .

This reprogram will take approximately 20 minutes. If one or both wheel bearing assemblies require replacement, an additional 25 to 45 minutes will be required. However, due to service scheduling requirements, your dealer may need your vehicle for a longer period of time.

To limit any possible inconvenience, we recommend that you contact your GM dealer as soon as possible to schedule an appointment for this repair.

Should your dealer be unable to schedule a service date within a reasonable time, you should contact the appropriate Customer Assistance Center at the number listed below. The Customer Assistance Center hours of operation are from 8:00 AM - 11:00 PM, EST, Monday through Friday.

If, after contacting the appropriate customer assistance center, you are still not satisfied that we have done our best to remedy this condition without charge and within a reasonable time, you may wish to write the Administrator, National Highway Traffic Safety Administration, 400 Seventh Street SW, Washington, DC 20590 or call 1-888-327-4236.

The enclosed customer reply form identifies your vehicle. Presentation of this form to your dealer will assist in making the necessary correction in the shortest possible time. If you no longer own this vehicle, please let us know by completing the form and mailing it back to us.

If your vehicle is within the New Vehicle Limited Warranty your dealer may provide you with shuttle service or some other form of courtesy transportation while your vehicle is at the dealership for this repair. Please refer to your Owner's Manual and your dealer for details on Courtesy Transportation.

More information about this recall (including answers to frequently asked questions) is available online at the Owner Center at My GMLink. This free online service offers vehicle and ownership-related information and tools tailored to your specific vehicle. To join, visit www.mygmlink.com and enter your vehicle's 17-character vehicle identification number (VIN) shown on the enclosed form to get the most personalized information for your vehicle.

We are sorry to cause you this inconvenience; however, we have taken this action in the interest of your safety and continued satisfaction with our products.

General Motors Corporation

Enclosure

04030