Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Cruise Control Disengaged
The engine control module (ECM) disengages the cruise control operation based on the signals from the following switches:
- The brake pedal position (BPP) sensor
- The cruise control on/off switch
- The cruise control cancel switch
The cruise control system will disengage when the brake pedal is applied. The instrument panel module (IPM) monitors the BPP sensor via the BPP sensor signal circuit as the voltage signal increases while the pedal reaches the fully applied position. The ECM monitors the BPP signal through a discrete input and a GMLAN serial data message signal from the IPM indicating the brake status. When both signals indicate the brake pedal is applied, the ECM will disengage the cruise control system. For further information on the BPP sensor, refer to Exterior Lighting Systems Description and Operation or Brake Pedal Position Sensor Calibration .
The cruise control system will also disengage when the cruise control on/off switch is switched OFF, or the cruise control cancel switch is activated. The rear integration module (RIM) determines when the cruise control cancel switch is activated. When the normally open cancel switch is closed, the RIM detects a high signal voltage on the cruise control cancel switch signal circuit. The RIM via the IPM sends a GMLAN serial data message to the ECM in order to disengage the cruise control system. The ECM then sends a GMLAN serial data message to the instrument panel cluster (IPC) in order to turn off the Cruise Engaged indicator. The vehicle speed stored in the memory of the engine control module will be erased when the cruise control On/Off switch is turned OFF, or the ignition switch is turned OFF. The Cruise Control System will also disengage when the ECM detects that a driver override function has been active for approximately 60 seconds.
Every time the cruise control system is disengaged, the ECM will keep track of the reason for system disengagement. The last 8 disengagement reasons will be recorded within the ECM memory. The scan tool will display the last 8 Cruise Disengage History parameters, in which one out of approximately 50 possible reasons will be displayed in each of these 8 parameters. For the disengagement reason to be displayed within the scan tool parameter either the cruise control system is active and disengagement is requested, or engagement of the system is requested but a fault is present. For a list of each disengagement reason along with each definition, refer to Engine Control Module Scan Tool Information (V6) or Engine Control Module Scan Tool Information (W/RPO LH2, LC3, LD8 or L37) .
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.