System Diagnosis
- Remove instrument cluster and the connectors to it. Measure the voltage to ground at the terminals below. Put the ignition switch in "RUN" but do not start the engine.
- If the speedometer is not working, check voltage at the vehicle speed input of the instrument panel. With the drive wheels rotating at 10 mph, the voltage between C15 and D11 is approximately 1.8 to 2.5 VAC.
- Resistance tests. With the Cruise Switch off, the ignition off and the negative battery cable disconnected, measure the resistance below.
- If all voltages and readings are correct, replace the instrument panel. If any measurement is bad, verify that the problem is in the cruise control servo and not in the connecting wires. Do this by measuring resistance at the servo with the connector removed.
- If the trouble system persist, diagnose the vacuum system, valves, and linkages.
NOTE:
If the voltage at a terminal is not correct, check the wiring to that terminal.