Diagnosis & Repair Procedure
- Perform DTC CONFIRMATION TEST . If DTC P0480 is set, go to next step. If DTC P0480 is not set, problem is intermittent. System is okay at this time. See TROUBLE SHOOTING - NO CODES article.
- Turn ignition on. Backprobing, measure voltage between ground and ECM 35-pin connector E92 terminal No. 3 (Orange/Black wire). See Figure . With engine coolant temperature less than 200°F (93°C), reading should be 10-14 volts. With engine coolant temperature 208°F (98°C) or more, reading should be 0-2 volts. If voltages are as specified, problem is intermittent. System is okay at this time. See TROUBLE SHOOTING - NO CODES article. Go to next step.
- If intermittent problem is not found, replace ECM and go to DTC CONFIRMATION TEST . If voltages are not as specified, go to next step.
- Turn ignition off. Remove radiator cooling fan relay from engine compartment fuse/relay block at left side of engine compartment. See Figure . Measure resistance between radiator cooling fan relay terminals No. 3 and 4. If resistance is 70-110 ohms, go to next step. If resistance is not 70-110 ohms, replace radiator cooling fan relay and go to DTC CONFIRMATION TEST .
- Inspect for open or short in Black/White wire between radiator cooling fan relay and ignition switch. Also check for open or short in circuit between radiator cooling fan relay and ECM 35-pin connector E92 terminal No. 3. See WIRING DIAGRAMS article. See Figure . Repair as necessary. If wires are okay, replace ECM and go to DTC CONFIRMATION TEST .