Brake Pedal Play May Affect Cruise Control Operation

Excessive brake pedal free play may cause the cruise control to not set or resume after braking on some 2022 Encore GX and Trailblazer models. It may be necessary to pull up on the brake pedal to engage cruise control. These conditions may be intermittent and cruise control operation may return to normal after the vehicle is turned off and restarted.

If the brake pedal moves rearward during acceleration (Fig. 5), it may cause an inaccurate Learned Release Position in the Engine Control Module (ECM) and the ECM Brake Pedal Position Sensor will show a value of 6% pedal travel or greater. As a result, the parameter for Cruise Control Inhibit Reason will show Brake Pedal Applied, causing cruise control to be disabled.

 

Fig. 5

 

To verify the brake pedal concern, monitor the Brake Pedal Position Sensor (BPPS) Learned Released Position and the Brake Pedal Position Sensor parameters in GDS 2 during a test drive with cruise control engaged. The data, found under ECM > Data Display > Automatic Transmission, shows the ECM is constantly learning. During acceleration, if there is movement in the brake pedal, the ECM will relearn the new, incorrect values that indicate the brake pedal is applied.

While performing a test drive, accelerate several times from 0-50 MPH. In the GDS 2 data, while the vehicle is accelerating (yellow line), the Brake Pedal Position Sensor (red line) will drop to a lower value than the normal release position, which causes a corresponding drop in the BPPS Learned Released Position (green line) value. The ECM will show some percentage of travel greater than zero when traveling at a steady speed with the pedal released (blue line). (Fig. 6) Under these circumstances, the parameter for Cruise Control Inhibit Reason will show Brake Pedal Applied.

 

Fig. 6

 

If these conditions are found, the brake and accelerator pedal assembly should be replaced. (Fig. 7)

 

Fig. 7

 

For more details, including additional information about the GDS 2 parameters, a video of the brake pedal movement and related part numbers, refer to Bulletin #22-NA-097.

– Thanks to Frank Jakubiec

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