Test B: Incorrect Fuel Gauge Reading

1. Test fuel gauge. See FUEL GAUGE  under COMPONENT TESTS. If fuel gauge operates properly, go to next step. If fuel gauge does not operate properly, go to step  4.
2. Visually inspect fuel tank for damage or deformation. If fuel tank appears okay, go to next step. If fuel tank does not appear okay, repair or replace as necessary. Retest system operation.
NOTE: Fuel level sensor/pump assembly may also be referred to as fuel pump module or fuel pump/fuel gauge sender.
3. Depress 2 clips securing front of rear seat cushion, and remove rear seat cushion. Visually inspect fuel level sensor/pump assembly wiring harness for damage. Remove fuel level sensor/pump assembly. See FUEL PUMP MODULE  under REMOVAL & INSTALLATION. Visually inspect fuel level sensor/pump assembly for damage or obstruction. If fuel level sensor/pump assembly and wiring harness appear okay, replace fuel level sensor. Retest system operation. If fuel level sensor/pump assembly and/or wiring harness appear damaged or obstructed, repair or replace as necessary. Retest system operation.
NOTE: Fuel level sensor/pump assembly may also be referred to as fuel pump module or fuel pump/fuel gauge sender.
4. Turn ignition switch to LOCK position. Disconnect fuel level sensor/pump assembly 6-pin harness connector C315. See Fig 1. Measure resistance between ground and fuel level sensor/pump assembly 6-pin harness connector C315 terminal No. 2 (Black/Green wire). If resistance is less than 5 ohms, go to next step. If resistance is more than 5 ohms, repair open in Black/Green wire. See WIRING DIAGRAMS . Retest system operation.
5. Turn ignition switch to LOCK position. Remove instrument cluster. See INSTRUMENT CLUSTER  under REMOVAL & INSTALLATION. Disconnect instrument cluster harness connectors. Measure resistance of Yellow/Brown wire between instrument cluster 10-pin harness connector C254 terminal No. 4 and fuel level sensor/pump assembly 6-pin harness connector C315 terminal No. 3. See Figure and Fig 1 . Resistance should be less than 5 ohms. Measure resistance between ground and instrument cluster 10-pin harness connector C254 terminal No. 4 (Yellow/Brown 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 . Retest system operation.
6. Measure resistance between ground and instrument cluster 10-pin harness connector C254 terminal No. 5 (Black/Green wire). If resistance is less than 5 ohms, go to next step. If resistance is more than 5 ohms, repair open in Black/Green wire. See WIRING DIAGRAMS . Retest system operation.
7. Visually inspect instrument cluster printed circuit for damage, cracks or hot spots. If instrument cluster printed circuit appears okay, replace fuel gauge and instrument cluster gauge amplifier. See FUEL GAUGE, TEMPERATURE GAUGE, SPEEDOMETER/ODOMETER & TACHOMETER INDICATORS/WARNING BULBS  and INSTRUMENT CLUSTER GAUGE AMPLIFIER  under REMOVAL & INSTALLATION. Retest system operation. If instrument cluster printed circuit appears damaged, replace printed circuit and gauge contact clips See PRINTED CIRCUIT  under REMOVAL & INSTALLATION. Retest system operation.

Fig 1: Identifying Fuel Level Sensor/Pump 6-Pin Harness Connector C315 Terminals

Courtesy of FORD MOTOR CO.