actually i almost forgot here is a service bulletin on this
Bulletin No.: 04-05-25-002E
Date: March 11, 2009
ABS Light On, DTCs C0265, C0201, U1041 Set and/or Loss of Communication with Brake Module (Reground EBCM Ground)
This bulletin is being revised to add step 2 to the procedure and update the Parts and Warranty Information. Please discard Corporate Bulletin Number 04-05-25-002D (Section 05 - Brakes).
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.
A poor connection at the EBCM ground is causing unnecessary replacement 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 |
Do not replace the brake module to correct this condition. Perform the following repair before further diagnosis of the EBCM.
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. If the original fastener has a welded on nut, remove the nut from the frame, and if required, enlarge the bolt hole to accommodate the new bolt and nut.
3. Clean the area, front and back, using a tool such as a *3M(TM) Scotch-Brite Roloc disc or equivalent.
4. 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.
5. Install a washer and nut to the back side of the frame.
Tighten the nut to 9 Nm (79 lb in).
6. Cover the front and back side of the repair area using Rubberized Undercoating.
An additional check can be made to ensure a good connection for the battery cable to frame ground. It is possible for this ground to cause similar symptoms with the ABS as described above.
*We believe this source and their products to be reliable. There may be additional manufacturers of such products/materials. General Motors does not endorse, indicate any preference for or assume any responsibility for the products or material from this firm or for any such items that may be available from other sources.