Speed Control Solenoid Circuits

WHEN MONITORED
The ignition key is in the ON position
And the SET button is pressed
And the PCM senses voltage at cavity 23.

SET CONDITION
When the vacuum and vent solenoids fail respond to actuation by the powertrain control module.

THEORY OF OPERATION
Speed Control System Activation
- ON/OFF switch in the ON position.

- Transmission gear selector in a gear other than park or neutral.

- Vehicle traveling forward at a speed between 35 and 85 mph.

Setting speed Control System
- Press the "Set" switch - the PCM locks in set speed.

- The PCM then maintains set speed by actuating the vacuum solenoid (to open the throttle), and the vent solenoid (to close the throttle).

- These actuations are dependent on power supplied to the servo, from the speed control relay, through the brake switch.

Deactivating System

- Depress brake pedal.
- Move ON/OFF switch to the OFF position.
- Vehicle speed falls below the minimum (35 mph).

Resuming Set Speed

- The Set Speed can be resumed by pressing the RESUME switch, while vehicle speed is between 35 and 85 mph, (if the other criteria above for system activation have been met).

PROBABLE CAUSES
- Solenoid control circuit open or shorted
- Vacuum or vent solenoid shorted or open
- Open power circuit to solenoids
- PCM failure