Cadillac XLR Knowledge Base

2009 Cadillac XLR: Service Information: Electronic Brake Control Module Communication

Source: GM Techlink

Date: October 2010

Subject:  Electronic Brake Control Module Communication

Models: 2009 Cadillac XLR

On some 2008-2011 Enclave; 2007-2011 Escalade, Escalade ESV, Escalade EXT, Avalanche, Silverado, Suburban, Tahoe, Acadia, Sierra, Yukon, Yukon XL, Yukon Denali, Yukon Denali XL; 2009 Cadillac XLR; 2010-2011 Camaro; 2009-2011 Corvette, Traverse; 2008-2009 G8; and 2007-2010 OUTLOOK models, with StabiliTrak (JL4), the ABS MIL and red Brake MIL may be illuminated on the instrument cluster.

When trying to retrieve DTCs for this condition, the scan tool will not communicate with the Electronic Brake Control Module (EBCM), but will communicate with all other high and low speed GM LAN modules. Some modules may have set a DTC U0121 against the EBCM.

During diagnostics, the power circuits, ground circuits, communication enable signal circuit, and GM LAN circuits going to the EBCM may test OK, which may lead to replacement of the EBCM. However, the condition may still be present after installing the new EBCM.

This condition may be caused by shorted yaw rate and lateral acceleration sensor supply voltage (circuit 2087, dark green) pulling down the internal circuitry of the EBCM. If circuit 2087 is backed out of the EBCM connector and communication returns, inspect for this circuit shorted to ground or a yaw sensor concern.

On some full-size utility vehicles, the circuit may be shorted under the passenger front seat at the rear camera module bracket.

Repair the circuit as necessary and reroute to prevent the condition from reoccurring.

- Thanks to Ron Erman

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