Fuel Pump Control System (Q45)
- Turn ignition switch to ON position. Pinch fuel hose (before fuel rail) with fingers. For 5 seconds after ignition is turned on, pulsation should be felt on fuel hose. If pulsation is felt, system is okay. If pulsation is not felt, go to next step.
- Turn ignition switch to OFF position. Remove fuel pump relay from fuse block No. 2. See Figure. Fuse block No. 2 is located under right side of instrument panel. Turn ignition switch to ON position. Measure voltage between ground and fuel pump relay cavities No. 2 and 3. See Figure. If battery voltage exists, go to step 4. If battery voltage does not exist, go to next step.
- Check the following:
- Check fuse No. 13 (15-amp) located in fuse block No. 1 under left side of instrument panel. See Figure.
- Check for poor connection at fuse block No. 1 connector M1 terminal 7A (Brown/White wire). See Figure.
- Check joint connector No. 19 (connector M128). See Figure and Figure .
- Check for poor connection at fuse block No. 2 connector M145 terminal 7N (Brown/White wire). See Figure.
- Check fuse No. 36 (15-amp) located in fuse block No. 2.
- Check for open or short between fuse and fuel pump relay.
Repair as necessary.
- Turn ignition switch to OFF position. Disconnect fuel pump harness connector located under trunk trim. Disconnect dropping resistor harness connector. See Fig 1. Check continuity of the following:
- Between fuel pump relay cavity No. 5 and fuel pump harness connector terminal No. 3 (Black/Yellow wire).
- Between fuel pump harness connector terminal No. 1 and dropping resistor harness connector terminal No. 2 (Green/Red wire).
- Between body ground and dropping resistor harness connector terminal No. 1 (Black wire).
Continuity should exist. Also, check circuits for short to ground and short to voltage. If problem is found, go to next step. If no problem is found, go to step 6.
- Check the following:
- Check for poor connection at fuse block No. 2 connector M143 terminal 3L (Black/Yellow wire). See Figure.
- Check for poor connection at Super Multiple Junction (SMJ) connector M141 terminal 69V (Black/Yellow wire). See Fig 2. Connector M141 is located near right kick panel. See Figure.
- Check for open or short between fuel pump relay and fuel pump.
- Check for poor connection at White, 10-pin in-line connector B63 terminal No. 7 (Green/Red wire). Connector B63 is located at right rear of trunk.
- Check for open or short between fuel pump and dropping resistor.
- Check for open or short between dropping resistor and body ground.
Repair as necessary. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
- Disconnect ECM harness connector. Check continuity between fuel pump relay cavity No. 1 and ECM harness connector terminal No. 41 (Gray wire). See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.Also, check circuit for short to ground and short to voltage. If problem is found, go to next step. If circuit is okay, go to step 8.
- Check the following:
- Check for poor connection at Super Multiple Junction (SMJ) connector F105 terminal 3T (Gray wire).
- Check for open or short between ECM and fuel pump relay.
Repair as necessary.
- Measure resistance between dropping resistor terminals. Resistance should be.9 ohms at 77°F (25°C). If resistance is as specified, go to next step. If resistance is not as specified, replace dropping resistor.
- Check fuel pump relay. See RELAYS under RELAYS & SOLENOIDS. If relay is okay, go to next step. If relay is not okay, replace fuel pump relay.
- Measure resistance between fuel pump terminals No. 1 and 3. See Fig 3. Resistance should be 0.2-5.0 ohms at 77°F (25°C). If resistance is as specified, go to next step. If resistance is not as specified, replace fuel pump.
- No problem is indicated at this time. Problem may be intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article.