Normal Operation

WARNING: This page is about a different car, the 2007 Lincoln Mark LT and 2007 Ford Pickup. However, it is still accessible from the selected car via links, so may be relevant.

The powertrain control module (PCM) sends a signal through circuit 151 (LB/BK) to the speed control switches, which passes through the clockspring. The return signal is sent through circuit 848 (DG/OG) and the clockspring. The stoplamp switch sends a voltage signal through circuit 511 (LG) to the PCM when the brake pedal is applied, and deactivates the speed control if engaged.

Vehicles equipped with a manual transmission have an additional clutch pedal position (CPP) switch. The CPP switch, normally closed, supplies a ground signal to the PCM through circuit 306 (TN/LB). When the clutch pedal is applied, the CPP switch moves to the open position causing the PCM to lose the ground signal and deactivate the speed control.

The speed control deactivator switch interrupts the power signal to the PCM through circuit 307 (BK/YE) when the brake pedal is applied firmly and passes the stoplamp switch trip point. This is a redundant signal to the PCM.

Possible Causes

PCM not configured for speed control
Speed control switch
Digital transmission range (TR) sensor
Clutch pedal position (CPP) switch
PCM