Diagnostic Procedure
CAUTION:
DO NOT use ECM ground terminals when measuring voltage. Damage to ECM transistor may result. Use engine ground.
For component location, see COMPONENT LOCATIONS . For connector terminal identification, see CONNECTOR IDENTIFICATION . For circuit diagrams, see Fig 1 . For ECM pin voltage reference values, see Fig 2 .
- Turn ignition off. Disconnect fuel level sensor unit (sub) harness connector. Turn ignition on. Check voltage between engine ground and fuel level sensor unit (sub) terminal No. 1 (component side). Battery voltage should exist. If battery voltage exists, go to step 3 . If battery voltage does not exist, go to next step.
- Check the following:
- Harness connectors B1 and M12.
- Harness for open or short between combination meter and fuel level sensor unit (sub).
Repair as necessary.
- Turn ignition off. Disconnect fuel level sensor unit (main) harness connector (B27). Check harness continuity between engine ground and fuel level sensor unit (main) harness connector B27 terminal No. 5. Continuity should exist. Also check harness for short to power. If problem is found, go to next step. If no problem is found, go to step 5 .
- Check the following:
- Harness connectors B1 and M12.
- Harness for open or short between ECM and fuel level sensor unit and fuel pump.
Repair as necessary.
- Disconnect ECM harness connector F101. Check harness continuity between ECM harness connector F101 terminal No. 69 and fuel level sensor unit (sub) harness connector B28 terminal 1, and between ECM harness connector F101 terminal No. 78 and fuel level sensor unit (main) harness connector B27 terminal No. 5. Continuity should exist. Also check harness for short to ground or short to power. If problem is found, go to next step. If no problem is found, go to step 7 .
- Check the following:
- Harness connectors B1 and M12.
- Harness connectors F102 and M72.
- Harness for open or short between ECM and fuel level sensor unit (main).
- Harness for open or short between ECM and fuel level sensor unit (sub).
Repair as necessary.
- Turn ignition off. Check harness continuity between fuel level sensor unit (sub) harness connector B28 terminal No. 2 and fuel level sensor unit (main) harness connector B27 terminal No. 2. Continuity should exist. Also check harness for short to ground and short to power. If problem is found, repair as necessary. If circuit is okay, go to next step.
- Remove fuel level sensor/FTT sensor. See FUEL PUMP MODULE under FUEL SYSTEMS in REMOVAL & INSTALLATION - EXCEPT I35 & QX4 article. Measure resistance between sensor terminals No. 4 and 5. With float at EMPTY position, resistance should be about 79-85 ohms. With float at FULL position, resistance should be about 2-3 ohms. If resistance is as specified, go to next step. If resistance is not as specified, replace fuel level sensor/FTT sensor.
- Remove fuel level sensor unit (sub). Measure resistance between sensor terminals No. 1 and 2. With float at EMPTY position, resistance should be about 41-45 ohms. With float at FULL position, resistance should be about 2-3 ohms. If resistance is as specified, go to next step. If resistance is not as specified, replace fuel level sensor unit (sub).
- No problem is indicated at this time. Problem may be intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article.