Test F: No Power In Start Position
- Turn ignition off. Disconnect ignition switch 15-pin connector. Measure voltage between ignition switch 15-pin harness connector terminals B4 (Light Green/Violet wire) and B5 (Light Green/Violet wire) and ground. See Figure. If both voltage values are greater than 10 volts, go to next step. If either voltage value is not greater than 10 volts, repair open circuit in suspect Light Green/Violet wire. See appropriate wiring diagram in POWER DISTRIBUTION article in WIRING DIAGRAMS. Test system for normal operation.
- Ensure ignition is off. Measure resistance of Red/Light Blue wire between ignition switch 15-pin harness connector terminal STA and junction box/fuse relay panel fuse No. 20 cavity. Then measure resistance of Red/Black wire between ignition switch 15-pin harness connector terminal I1 and junction box/fuse relay panel fuse No. 29 cavity. See Fig 1. If both resistance values are less than 5 ohms, go to next step. If either resistance value is not less than 5 ohms, repair open circuit in suspect circuit. See appropriate wiring diagram in POWER DISTRIBUTION article in WIRING DIAGRAMS. Test system for normal operation.
- Remove and test ignition switch. See IGNITION SWITCH under COMPONENT TESTS. If ignition switch is faulty, replace ignition switch, and retest system. See IGNITION SWITCH under REMOVAL & INSTALLATION. If ignition switch is okay, repair starter concern. See appropriate STARTERS article in STARTING & CHARGING SYSTEMS.
Courtesy of FORD MOTOR CO.