Motor Circuit Testing

RADIATOR FAN MOTOR INOPERATIVE
Fan Relay and Engine Controller Operated.

EQUIPMENT REQUIRED
1. Diagnostic Tool DRBII or equivalent
2. Volt/Ohm Meter
3. Wiring Diagrams Manual

TEST PROCEDURE
1. Bring the engine to normal running temperature.
2. Check wiring connector in C25, C9, and C26 for proper engagement, Electrical Diagrams
3. Using a diagnostic tool, plugged into the diagnostic connector rearward of the battery, check the On-Board Diagnostics (OBD) in the Single Board Engine Control (SBEC) for fault codes, "Fuel Injection" for instructions.
4. If fault code 88-12-35-55 is detected, proceed to Step 5.
5. With the ignition switch in the run position, test for battery voltage at single pin connector at the fan relay. Voltage reading OK, proceed to Step 6a. Voltage at 0-1 volt, proceed to Step 6b.

Fig. 37 Engine Controller 60-way Connector:

6a. With the ignition off, disconnect the 60-way connector from the SBEC (outboard of battery) and return the ignition to the run position. Test for battery voltage at cavity 31 of the 60-way connector. Voltage reading OK and female terminal is not damaged, replace the SBEC. Voltage reading 0, repair open or short in C27 circuit.
6b. With the ignition off, disconnect the 60-way connector from the SBEC (outboard of battery) and return the ignition to the run position. Test for battery voltage at the single pin connector at the fan relay. Voltage reading OK, replace the SBEC. Voltage reading 0-1 volt, proceed to Step 7.
7. With ignition in the run position, test for battery voltage at the blue wire (C27) in the 3-way connector of the fan relay. Voltage reading OK, replace the fan relay. Voltage reading 0, repair open or short, in C27 circuit.
8. Turn ignition off, connect the 60-way connector at the SBEC, and test the system.