Test B: Fuel Gauge Inaccurate

Test fuel gauge. See FUEL GAUGE under COMPONENT TESTS. If fuel gauge is okay, go to next step. If fuel gauge tests bad, go to step 4 .
Visually inspect fuel tank. Repair or replace as necessary. If fuel tank is okay, go to next step.
Visually inspect fuel level sensor/pump assembly and wiring harness. Repair or replace as necessary. If fuel level sensor/pump assembly and wiring harness are okay, replace fuel level sensor.
Turn ignition off. Disconnect fuel level sensor/pump connector. Measure resistance between ground and fuel level sensor and pump harness connector terminal No. 2 (Black wire). See Fig 1 . Resistance should be less than 5 ohms. If resistance is less than 5 ohms, go to next step. If resistance is more than 5 ohms, repair open in Black wire. See WIRING DIAGRAMS .

Fig 1: Identifying Fuel Level & Pump Harness Connector
Courtesy of FORD MOTOR CO.
Turn ignition off. Remove instrument cluster. See INSTRUMENT CLUSTER under REMOVAL & INSTALLATION. Disconnect instrument cluster harness connector C254. See Figure . Measure resistance of Yellow/Brown wire between instrument cluster harness connector C254 terminal No. 4 and fuel level sensor/pump harness connector terminal No. 3. See Figure and Fig 1 . Resistance should be less than 5 ohms. Measure resistance between ground and instrument cluster harness connector C254 terminal No. 4 (Black/Yellow wire). Resistance should be more than 10 k/ohms. If resistance is as specified, go to next step. If resistance is not as specified, repair open or short to ground in Yellow/Brown wire. See WIRING DIAGRAMS .
Measure resistance between ground and instrument cluster harness connector C254 terminal No. 5 (Black/Green wire). Resistance should be less than 5 ohms. If resistance is less than 5 ohms, go to next step. If resistance is more than 5 ohms, repair open in Black/Green wire between instrument cluster harness connector and ground. See WIRING DIAGRAMS .
Visually inspect instrument cluster printed circuit for damage, cracks or hot spots. Replace as necessary. If instrument cluster printed circuit is okay, replace fuel gauge and retest system. If vehicle is equipped with fuel/temp gauge assembly, replace instrument cluster gauge amplifier. See INSTRUMENT CLUSTER GAUGE AMPLIFIER under REMOVAL & INSTALLATION.