Ground Circuits
WARNING: This page is about a different car, the 2003 Ford Pickup. However, it is still accessible from the selected car via links, so may be relevant.
Turn ignition off. Disconnect AFCM 90-pin connector. AFCM is located in right front of engine compartment. Using DVOM, check for continuity between chassis ground and AFCM connector terminals No. 1, 2, 3, 4, 17, 19, 21, 23, and 75. See Fig 1. If continuity exists, go to next step. If continuity does not exist, repair open in affected ground circuit. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS - F150 article in ELECTRICAL.