Cruise Control Inoperative - keywords applied brake intermittent lamp nostop stop lamp switch

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

A customer may comment the Cruise Control will not set or shuts off while driving.

Monitor the Stoplamp Pedal Switch reading with the Tech2: Engine> Engine Controls> Data Display> Engine Control Module> Engine Data 1> Stoplamp Pedal Switch. If the Stoplamp Pedal Switch is shown to be applied when the brake pedal is not applied, inspect circuit 17 Stop Lamp Switch Signal for poor connections or an open circuit condition between the Engine Control Module (ECM) and C205 Body Harness to I/P Harness Left.

Document ID# 1623783 is the schematic for circuit 17. The ECM sends voltage (approximately 7.5v) onto circuit 17 to monitor the Stoplamp operation. The ECM will sense low voltage (approximately .16v) when the Stoplamps are OFF and the circuit is not open. When the Stoplamps are ON the ECM will sense high voltage. Once voltage raises to a certain threshold the ECM will turn off the Cruise Control.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.