Sierra 1500 2WD V6-4.3L (2008)
Brake Rotor/Disc: All Technical Service Bulletins
Brakes - Front Brake Induced Pulsation/Vibration
TECHNICAL
Bulletin No.: 10-05-23-001B
Date: April 13, 2011
Subject: Brake Induced Pulsation/Vibration Felt in Steering Wheel, Rumble Noise from Underbody During Downhill Descent (Verify Condition and
Replace Front Brake Pads)
Models:
2008 Chevrolet Silverado Light Duty (LD)
2008 GMC Sierra Light Duty (LD)
2nd-Design Only - w/ Pad Spreading Spring Clips (Refer to PIT4611 for Design Identification)
Equipped with Disc/Drum Brakes (RPO JF3) and Stabilitrak (RPO JL4)
2009-2012 Chevrolet Silverado Light Duty (LD)
2009-2012 GMC Sierra Light Duty (LD)
Equipped with Disc/Drum Brakes (RPO JF3) and Stabilitrak (RPO JL4) or (RPO JF7) and Stabilitrak (RPO JL4)
Supercede:
This bulletin is being revised to add the 2012 model year. Please discard Corporate Bulletin Number 10-05-23-00A (Section 05 - Brakes).
Condition
Some customers may comment on a pulsation or vibration mostly concentrated in the steering wheel during downhill descent as specifically described.
This condition will most often begin as an increasing rumbling noise coming from the underbody or the front of the vehicle. This condition is exhibited
mostly in mountainous regions.
Note
Use care to ensure the following diagnosis and repair are only attempted if the conditions and concern match those listed, and if the concern can be
duplicated under the same conditions.
This condition occurs ONLY
under the following conditions:
-
When the vehicle is driven as follows:
-
On a downhill descent on a fairly steep grade (approximately 5% or greater).
-
On taller hills (roughly 1.5‹›km [1‹›mi] road length or greater), without sharp turns.
-
At speeds above 64‹›km/h (40‹›mph).
-
Using the brakes just enough to maintain the speed limit when moving downhill.
-
Typically, a rumbling noise will be heard first, building in intensity, followed by increasing pulsation, or vibration, felt in the steering wheel, then
typically felt in the floor panel.
-
The condition will be eliminated once the vehicle is driven on relatively flat ground, typically for 1.5-3‹›km (1-2 mi).
Cause
This condition may be caused by interaction between the front brake lining material and the front brake rotors.
Correction
Important
DO NOT attempt any repairs on the vehicle until you verify the specific condition is present by following the steps below:
1. Warm up the vehicle by driving approximately 8 km (5 mi).
2. Drive the vehicle in the lane closest to the side of the fairly steep grade (roughly 5 percent or greater), taller hill (roughly 1.5 km [1‹›mi] road
length or greater), without sharp turns, and with a speed limit of 64 km/h (40 mph) or greater, with the side windows down.
3. While in Drive, descending downhill, apply the brakes naturally, only as needed, to maintain the speed limit.
4. Observe for noise, followed by pulsation/vibration. Observe where the noise, pulsation and/or vibration are most noticeable.
5. Drive the vehicle on relatively flat ground for 1.5-3 km (1-2 mi) to verify that the condition goes away completely.
Note
