This bulletin applies to 2007-2011 Cadillac DTS models. Some customers may comment that cruise control will not engage or will not stay engaged, and there may be no DTCs. Scan tool cruise disengage history is “Brake.” This condition may occur due to a faulty brake pressure sensor, located in the Brake Pressure Modulator Valve (BPMV).
1. Verify that scan tool cruise disengage history parameter reads “Brake.” Diagnose any other scan tool cruise disengage history first using eSI diagnostics. Note: Scan tool cruise disengage history parameter will read “Brake” based on either of the following two inputs:
a. BCM detecting a brake pedal apply using brake pedal position sensor (BPP).
b. EBCM detecting a brake pedal apply using the brake pressure sensor within BPMV.
2. Verify that DTC P0703, P0572 and P0573 is not set. If any of these are set, refer to eSI for the proper DTC diagnostics.
3. With the brake pedal fully released, verify the EBCM indicates brake released. Tech 2 Chassis => EBCM => Data Display => VSES => BPP Signal parameter = “Released.”
4. While BPP signal parameter still reads “Released,” verify the Brake Pressure Sensor Input scan tool parameter value is equal to or less than 0.5V. If greater than specified value with no other scan tool cruise control disengage history, and the cruise control is inoperative, replace the BPMV.
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