Cruise Control: Description and Operation

VEHICLE SPEED CONTROL
The vehicle speed control system is powered by the Powertrain Control Module (PCM). The vehicle speed control switches, located in the steering wheel, use resistors internal to the switch to send a signal to the PCM indicating what the operator is requesting. The V37 circuit, from cavity 31 of the PCM supplies power for the switch. Circuit Z1O is the ground for the switch. The Z1O circuit terminates at the instrument panel right center support.

When the system is turned ON, the vehicle is moving forward, vehicle speed is above 35 mph, and the SET switch is depressed, the PCM looks at the vehicle speed through the vehicle speed sensor. With this information, the PCM sends a signal to the vehicle speed control servo, on the V36 circuit, and the servo applies vacuum to hold the desired speed. Circuit V36 connects to cavity 40 of the PCM.

When the operator selects the COAST feature in the system, the PCM measures the resistance on the V37 circuit and uses this information to apply voltage on the V35 circuit, which is the vent side of the vehicle speed control servo. Circuit V35 connects to cavity 60 of the PCM.

Grounding for the vehicle speed control servo is done on the Z1 circuit. Circuit Z1 terminates at the left headlamp ground located on the left side of the radiator closure panel. An additional input to the servo is provided by the stop lamp switch on the V40 circuit.

Circuits V32 and K29 are used as inputs to the PCM to indicate when the operator is applying the brakes, as vehicle speed control is canceled when this happens. Circuit V32 connects to cavity 47 of the PCM. Circuit K29 connects to cavity 32 of the PCM.