Initial Inspection and Diagnostic Overview

Cruise Control Voltage/Resistance Chart:

SYSTEM CHECK (ROAD TEST)

Perform the following check with the cruise control main switch on, while driving faster than 25 mph.

1. Depress the set/coast switch. The vehicle should maintain its set speed. You shouldn't have to put your foot on the accelerator.

2. With your foot off the accelerator, hold the set/coast switch in. The car should coast to a slower speed.

3. Release the set/coast switch. The cruise control system should engage and hold the slower speed - if the speed is above 25 mph.

4. Hold the resume/accel switch. The vehicle should accelerate.

5. Release the resume/accel switch. The vehicle should hold the new faster speed.

6. Tap the brake pedal. The cruise control system should disengage.

7. Tap the resume/accel switch. The vehicle should accelerate to its former speed.


If the vehicle has a manual transmission, repeat steps 6 and 7 by depressing the clutch and placing the transmission in neutral. With automatic transmission, repeat steps 6 and 7 by placing the transmission in neutral and then in drive.

8. While cruising, accelerate and then take your foot off the accelerator. The vehicle should coast back to the set speed.

9. While cruising, tap the resume switch. The vehicle's speed should increase about 1 mph for each tap.

10. While cruising, tap the set switch. The vehicle's speed should decrease about 1 mph for each tap.

11. Depress the cruise control switch. The cruise control should turn off.


SYSTEM DIAGNOSIS

1. Check fuse 8.

2. No matter what the symptoms, disconnect the control unit connector and check the wires in it for voltage and resistance.
- Check the voltage at each wire listed in the first chart (all checks are to body ground). Use a digital multimeter for all measurements.
^ If the voltage is not correct at a cavity in the connector, repair or replace the circuit that connects to that cavity.
^ If the voltage readings are correct, make sure the ignition switch is off, and then disconnect the battery and check resistance as described below.
- Check the resistance of the wires listed in the second chart (all checks are between each wire and ground).
^ If the resistance is not correct at a cavity in the connector, repair or replace the circuit that connects to that cavity.
^ If all the resistance measurements are good, go on to step 3.

3. If you found no problems on the previous check, gently twist the connector pins on the control unit about ten degrees with a pair of needle-nose pliers to increase the contact pressure. Attach the connector to the control unit, and then test drive the vehicle again.
- If the cruise control won't set, replace the control unit.
- If the cruise control disconnects after some time, carefully check the control unit connector for loose terminals or other signs of poor contact.
- If the cruise control will set but won't hold its set speed, check the actuator in accordance with the Workshop Manual.
- If the cruise control will set but feels erratic or surges, replace the speedometer cable.
- If the speedometer cable has been replaced and the cruise control still is erratic or intermittent, measure the voltage at pin 13 with the connector unit attached, the rear end raised and the wheels turning at 60 mph Voltage should be between 1.5 and 2.5 volts if the pulse generator is operating normally. If the voltage is not correct, replace the speedometer.