1. Radiator Fan Control Module

WARNING: WHILE MONITORING ENGINE COOLANT TEMPERATURE WITH THE DRB III(R), DO NOT ALLOW THE ENGINE COOLANT TEMPERATURE TO RISE ABOVE 102°C (215°F) WITH THE RADIATOR FAN CONTROL MODULE DISCONNECTED.

NOTE: If an Engine Coolant Temperature (ECT) Sensor fault has been set, diagnose the Engine Coolant Temperature Sensor faults before continuing.

Turn the ignition off.

Disconnect the PCM C4 harness connector.

NOTE: Check connectors - Clean/repair as necessary.

Turn the ignition on.

Measure the voltage of the Radiator Fan Control circuit at the Radiator Fan Control Module harness connector.

Fig 1: Measuring Voltage Of Radiator Fan Control Circuit

Courtesy of DAIMLERCHRYSLER CORP.

Is the voltage above 10 volts?

Yes >> 2
No >> Replace the Radiator Fan Control Module. See COOLING SYSTEM (MECHANICAL) article.
See POWERTRAIN VERIFICATION TEST - VER 2 .