EI08222 - Brake Noise and/or Pulsation - Information on FNC Brake Rotor Parts Restriction

Important: For Buick Lucerne or vehicles located outside North America -- disregard this bulletin. Diagnose and repair according to information found in SI. Refer to Corporate Bulletin Number 00-05-22-002K for Brake Service procedure information. If a rotor must be replaced for any reason, the technician must contact the Product Quality Center (PQC) at 1-866-654-7654.

The purpose of this bulletin is to explain the FNC brake rotor parts restriction for the 2009 Cadillac DTS. The parts restriction program will be in effect for a minimum of the first three months of production (through October 31, 2008).

Part Numbers Covered Under the Restriction

The following part numbers are covered under the restriction:

Background

All vehicle manufacturers are challenged when trying to design the optimal brake rotor and brake pad combination. These issues go well beyond the basic braking factors like stopping distance, rotor and pad wear. Some other important customer issues that need to be taken into consideration are; the customer’s expectations of braking performance, brake rotor corrosion, brake pulsation, brake noise and dust. Designing the ultimate brake rotor and brake pad combination for all of these elements can become a real balancing act.

Ferritic Nitro-Carburizing (FNC) Technology

Beginning with the 2009 Cadillac DTS, GM is introducing a new brake rotor technology called Ferritic Nitro-Carburizing (FNC). Simply put, it is an additional step in the manufacturing process of the brake rotor which creates a hardened outer layer on the surface of the rotor. This hardened outer layer reduces the rotor rusting (corrosion) and it also allows the rotor to wear slower. Since this new technology protects against excessive rotor corrosion, it not only aesthetically looks better through open spoke type wheels, it helps reduce thickness variation which creates pulsation specifically due to "lot rot" corrosion (while the vehicle sits on the dealer’s lot between build delivery and customer delivery).

DO NOT TURN THE ROTOR(S).

Due to the implementation of the FNC technology, engineering needs to be made aware of any concerns related to brake pulsation during the launch timing (August 1 thru October 31, 2008). If a customer brings their 2009 Cadillac DTS in with a complaint of brake pulsation related to brake pad/rotor, follow the diagnostic procedure below. If diagnosis leads to brake rotor refinish, DO NOT Refinish the Rotor. The rotor should be Replaced and sent back to the Warranty Parts Center for Engineering Evaluation. Be sure to document all information on the repair order:

1. Can the noise/pulsation be heard/felt while the vehicle is moving with the brake pedal applied?

•	Yes -- proceed to Step 2.

•	No -- this concern is not caused by the brake rotor or pad. Do not proceed with this bulletin. Refer to SI for diagnosis and repair.

2. Describe the customer's complaint on the Repair Order. (i.e. squeak, squeal, growl, pulsation, vibration, shudder, etc.)
3. Can the concern be felt through the steering wheel or pedal? If so, describe on the Repair Order what is being felt and at what speed.
4. Perform a visual inspection of the brake rotor(s) and pads. Describe on the Repair Order any unusual wear or corrosion.

-	If the brake pads are NOT worn, proceed with Step 5.

-	If the brake pads are unevenly worn side to side and/or inner to outer, determine cause, correctioin and describe on Repair Order, proceed with Step 7.

5. Burnish brakes by performing 10-15 moderate stops from 56-64 km/h (35-40 mph) with cooling time between stops. Did this correct the customer's concern?

•	Yes -- no further action is required. Proceed to Step 9.

•	No -- proceed to Step 6.

6. If the customer's complaint is noise related, proceed with Step 7. If the customer's complaint is pulsation related, proceed with Step 8.
7. Replace the brake pads. Did this correct the customer's concern?

•	Yes -- no further action is required. Proceed to Step 9.

•	No -- proceed to Step 8.

8. Replace the rotor(s). Contact the PQC at 1-866-654-7654 to obtain parts. The original parts will be requested back for analysis using the Warranty Parts Center return process. Proceed to Step 9.
9. Fax the front and back of the completed repair order to:

Attn: Dennis Gravel

Fax #: 586-947-7160

For vehicles repaired under warranty, select the appropriate labor operation based on the repair that corrected the customer's concern: