File in Section:
Bulletin No.:

Service Bulletin

Date:

05 - Brakes
12-05-23-001
December, 2012

TECHNICAL
Subject:

Pulsation or Vibration Felt in Steering Wheel During Moderate Brake Apply at Highway
Speeds

Models:

2013 Cadillac XTS Limo (RPO V4U, W30) Hearse (RPO B9Q) Armored Car (RPO B05)
Models

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 may also be exhibited 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 brake is applied at a moderate rate,
while driving at highway speeds of 80 km/h
(50 mph) or more.
• The condition starts as the brakes get hot
(during application).
• 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.

Cause

Note: If the front pad kit listed is used to correct any
condition other than the condition described in this
bulletin, the vehicle could experience higher
mileage corrosion-induced brake pulsation.
If the condition described HAS NOT been verified, or if
the condition observed IS NOT most noticeable through
the steering wheel, the observed condition may have a
different cause, such as a tire/wheel or rear brake
issue, etc. Refer to SI for any further related
diagnostics.
If the condition described has been verified, and if the
condition is most noticeable through the steering wheel,
and if the condition was not present when brakes were
not warmed up, typically for initial brake apply, perform
the following inspection and repair.
Important:
• It is critical to use the proper OEM brake
rotors. Use of Non-OEM rotors may prevent
the condition from being corrected long term.
• If Non-OEM rotors are identified, these rotors
are NOT covered under the GM New Vehicle
Limited Warranty.
1. Inspect the front brake rotors to ensure that they
are OEM rotors.
• Remove the brake rotor from the vehicle.

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 at highway speed, where
possible. Make sure that the brakes are not heated
prior to the observation.
3. With a speed limit of 64 km/h (40 mph) or greater,
with the side windows down, while in Drive, apply
the brakes naturally, only as needed, to maintain
the speed limit. Observe for noise, followed by
pulsation/vibration, as the brakes are warmed up
by brake application.
2405974
Copyright 2012 General Motors LLC. All Rights Reserved.

Page 2

December, 2012

Bulletin No.: 12-05-23-001

Note: To prevent a noise concern, follow the brake pad
insulator preparation and seating instructions as
referenced in Front Brake Pad Replacement (1500)
in SI.
6. Install the specified front pad kit, GM
P/N 25910432. Follow SI procedures.
7. Ensure that the condition has been eliminated
under the same conditions.

Parts Information
Part Number

Description

25910432

Pad Kit, Front Disc Brake

25819670

Rotor, Front Brake

Warranty Information
2405977

2.
3.
4.
5.

• Inspect the back side of the rotor for the Bosch
Logo. If the Bosch logo IS NOT present, replace
with OEM GM rotors, P/N 25819670.
Inspect the front brake rotors for Assembled
Lateral Runout (LRO) and thickness variation.
Follow SI procedures.
Inspect the front brake rotors for minimum
thickness. Follow SI procedures.
If the rotors are within specifications, DO NOT
refinish or replace the rotors.
If the rotors are out of specifications, refinish the
rotors on a qualified lathe, or replace the rotors as
appropriate. Follow SI procedures.

For vehicles repaired under warranty, use:
Note: H9745 includes time for road testing and for
removal of 1 rotor to inspect for OEM markings.
Labor
Operation

Description

Labor
Time

H9745*

Pads, Disc Brake-Front – R&R
Or Replace & Diagnose

1.2 hrs

Add

To Refinish Rotor - One

0.3 hr

Add

To Refinish Rotor - Both

0.6 hr

Add

To Replace Rotor - One

0.1 hr

Add

To Replace Rotor - Both

0.3 hr

*This is a unique labor operation for bulletin use only. It will
not be published in the Labor Time Guide.

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these
technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper
service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a
job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your
vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the
information.

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