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TSB's: Brakes

sperry

Silent Avalanche RIP
SM 2007
SM 2006
SM 2005
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Note: Content within this topic, as well as other topics in this section is for CACNA Members only. It is NOT for commercial use in any form, by anyone. (Except GM)

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Antilock Brake (ABS) Activation at Low Speeds (Clean Wheel Speed Sensor Mounting Surface) #03-05-25-007A - (Sep 3, 2004)

2002-2004 Cadillac Escalade, Escalade EXT

2003-2004 Cadillac Escalade ESV

1999-2004 Chevrolet Silverado

2001-2004 Chevrolet Suburban, Tahoe

2002-2004 Chevrolet Avalanche

2003-2004 Chevrolet Express

1999-2004 GMC Sierra

2001-2004 GMC Yukon, Yukon XL

2003-2004 GMC Savana

2003-2004 HUMMER H2

This bulletin is being revised to update the correction information. Please discard Corporate Bulletin Number 03-05-25-007 (Section 05 -- Brakes).

Condition

Some customers may comment on ABS activation at low speeds, usually below 8 km/h (5 mph). Upon investigation, the technician will find no DTCs set.

Cause

The cause of this condition may be an increased air gap between the wheel speed sensor and the hub reluctor ring due to rust and debris built up on the sensor mounting surface.

Correction

Measure AC voltage and clean the wheel speed sensor mounting surfaces.

  1. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in the General Information sub-section of the Service Manual (SI Document ID #899664).
  2. Disconnect both the front wheel speed sensor connectors at the frame and harness.
  3. Place a Digital Volt Meter (DVM) across the terminals of each wheel speed sensor connector.
  4. Rotate the wheel clockwise approximately one revolution per second. The minimum reading should be at least 350 ACmV's. If the reading is less than 350 ACmV's, remove the wheel speed sensor. Refer to the applicable Wheel Speed Sensor Replacement procedure in the ABS sub-section of the Service Manual.
  5. Plug the wheel speed sensor bore in order to prevent debris from falling into the hub during service.
  6. Clean the wheel speed sensor mounting surface using a wire brush, sand paper, emery cloth, scotch brite, or other suitable material. Be sure to thoroughly clean the wheel speed sensor surface. There should be no rust or corrosion.
  7. Check the sensor head to determine if it has been warped/distorted due to the corrosion build up or other causes. Check the mounting surface on the sensor head for flatness by placing it on the edge of a metal machinists scale or other suitable straight edge to measure the flatness. Check the sensor for flatness in multiple (minimum 3) positions/directions. If the sensor head is distorted, replace the sensor.
  8. Apply a thin layer of bearing grease to the hub surface and sensor O-ring prior to sensor installation. Use ONLY Wheel Bearing Lubricant, P/N 01051344 (Canadian P/N 993037).
  9. Install either the original sensor or a new one in the hub. Ensure that the sensor is seated flush against the hub. Refer to the applicable Wheel Speed Sensor Replacement procedure in the ABS sub-section of the Service Manual.
  10. Place the DVM across the sensor terminals and recheck the voltage while rotating the wheel. The voltage should now read at least 350 ACmV's.

Parts Information

Part Number Description

01051344 Wheel Bearing Lubrication - Tub
(Canadian P/N 993037)

Parts are currently available from GMSPO.

Warranty Information

For vehicles repaired under warranty, use:

Labor Operation Description     Labor Time

H2412 Sensor, Wheel Speed (Front Both) - Use published labor operation time
  Replace 
 
Supplement to 04094 Front Wheel Speed Sensor Corrosion - keywords brake abs unwanted campaign #PIT3455 - (Feb 21, 2005)

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in the PI.

Condition/Concern:

U.S. Dealers may receive a Canadian vehicle involved in Campaign 04094 and question if they should perform the campaign and/or the availability of the lubricants listed in the Campaign.

Recommendation/Instructions:

U.S. Dealers should perform the Campaign, but use the lubricant part numbers listed below.

Canadian Part #      U.S. Part #  Description

89022218                89022217  Lubricant, Rust Penetrating (will service 50+ vehicles)

993037                    1051344    Lubricant, Wheel Bearing (will service 25+ vehicles)

Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

Models:

(1999-2002 CHEVROLET SILVERADO) and (2000-2002 CHEVROLET TAHOE, SUBURBAN) and (2002 CHEVROLET AVALANCHE) and (1999-2002 GMC SIERRA) and (2000-2002 GMC YUKON, YUKON XL)
 
ABS Light On, DTCs C0265, C0201, U1041 Set and/or Loss of Communication with Brake Module (Reground EBCM Ground) #04-05-25-002B - (Mar 23, 2005)

2004-2005 Buick Rainier

2002-2005 Cadillac Escalade, Escalade EXT

2003-2005 Cadillac Escalade ESV

1999-2005 Chevrolet Silverado

2000-2005 Chevrolet Suburban, Tahoe

2002-2005 Chevrolet Avalanche, TrailBlazer, TrailBlazer EXT

2003-2005 Chevolet SSR

1999-2005 GMC Sierra

2000-2005 GMC Yukon, Yukon Denali, Yukon XL

2002-2005 GMC Envoy, Envoy XL, Sierra Denali

2004-2005 GMC Envoy XUV

2002-2004 Oldsmobile Bravada

This bulletin is being revised to update the parts information and add 2005 model year vehicles. Please discard Corporate Bulletin Number 04-05-25-002A (Section 05 -- Brakes).

Condition

Some customers may comment that the ABS light is on. Upon further inspection, DTCs C0265 and C0201 may be set in the brake module. It is also possible for DTC U1041 to set in other modules. There may also be a loss of communication with the brake module.

Cause

A poor connection at the EBCM ground is causing unnecessary replacements of brake modules.

Important: The EBCM Ground is different for each application. Refer to the list below for the proper ground reference:

  ? Midsize Utilities = Ground 304
  ? SSR = Ground 400
  ? Fullsize Trucks and Utilities = Ground 110

Correction

DO NOT REPLACE THE BRAKE MODULE.

Perform the following steps to improve the connection of the EBCM Ground:

  1. Remove the EBCM Ground. The EBCM Ground is located on the frame beneath the driver's side door. If multiple grounds are found in this location, the EBCM ground can be identified as the heavy (12-gauge) wire.
  2. Clean the area, front and back, using a Whiz Wheel?.
  3. Install the ground, then the washer and then the bolt to the frame.

      Important:  It is important to use the bolts, washers and nuts specified in this bulletin. These parts have been identified due to their conductive finish.

  4. Install a washer and nut to the backside of the frame.

      Tighten

      Tighten the nut to 9 N?m (79 lb in).

  5. Cover the front and back side of the repair area using Rubberized Undercoating.
 
ABS Light On DTC C0055, C0235, C0236 or C0237 Stored in the EBCM - keywords brake lamp sensor speedometer VSS #PIT3521 - (Apr 5, 2005)

1998-2005 All Chevrolet, GMC, Buick and Oldsmobile Mid-Sized Trucks and Utilities

1998-2005 All Chevrolet, GMC and Cadillac Full Sized Trucks and Utilities

1998-2005 All Chevrolet Express and GMC Savanna Full Sized Vans

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in the PI.

Condition/Concern:

ABS light on speedometer may be erratic. DTC C0055 C0235 C0236 or C0237 stored in the EBCM. This concern may be intermittent and not easily reproduced.

Recommendation/Instructions:

Using the Tech 2, check the ECM, PCM and/or TCM for any speed sensor related DTCs. These DTCs will need to be diagnosed first. Follow published diagnostics for related DTCs, repair and evaluate the vehicle after repairs are complete. If no DTCs exists in any other module, inspect the rear VSS sensor circuit(s) from the rear VSS sensor to the related module (ECM, PCM or TCM) for integrity. These circuits are 821 and 822 or 400 and 401 depending on model and model year (use SI to locate the schematic that applies to your application). Repair or restring these two circuits as needed. Evaluate the vehicle.

Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.
 
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