Diagnostic Test

1) MEASURE THE RESISTANCE OF THE SERIAL COMMUNICATION K1 CIRCUIT

Fig 1: Checking Serial Communication Circuit
Courtesy of DAIMLERCHRYSLER CORP.

Turn the ignition off.

Disconnect the Instrument Cluster harness connector.

Disconnect the A/C Heater Control Module harness connector.

NOTE: Check connectors - Clean/repair as necessary.

Measure the resistance of the Serial Communication K1 circuit from the Instrument Cluster harness connector to the A/C Heater Control Module harness connector.

Is the resistance below 5.0 ohms?

Yes
1. Replace the Instrument Cluster. (Refer to ELECTRICAL/INSTRUMENT CLUSTER - REMOVAL) .
2. Perform BODY VERIFICATION TEST .
No
1. Repair the Serial Communication K1 circuit for an open.
2. Perform BODY VERIFICATION TEST .