Wiring Diagrams — Ford F-150 1987-1991

Technical Reference

Member-uploaded diagrams & documents for this generation. AI-classified; community-verified where badged.

Wiring Diagrams

• Ford 5.0L & 5.8L TFI Ignition System Wiring Diagram - EEC, Coil, SPOUT Circuit
  This document is a Ford factory-style wiring schematic for the ignition system on 5.0L and 5.8L engines, filed as a wiring diagram for a 1991 Ford F-150. It shows the TFI (Thick Film Ignition) ignition system circuit…
• 1988 Ford F-150 4.9L EEC-IV Wiring Diagram - ECU Pinout & Sensor Wire Colors
  This document is an EEC-IV engine control wiring diagram for the Ford 4.9L inline-six engine, labeled "4.9L ELECTRONIC CONTROL ASSEMBLY." It shows the full 60-pin ECU connector pinout with signal names and wire colors…
• Ford Horn Relay Wiring Diagram & Horn Switch Bypass - High/Low Pitch Horns
  This document is a two-panel horn circuit wiring diagram, apparently taken from a Ford EVTM (Electrical & Vacuum Troubleshooting Manual) and modified to show a horn switch bypass. The left panel shows the factory horn…
• 1988 Ford F-250 Diesel Start/Glow Plug Control Wiring Diagram - EVTM Page 31
  This is page 31 of a Ford Electrical & Vacuum Troubleshooting Manual (EVTM) showing the Start/Glow Plug Control/Run circuit wiring diagram for a diesel engine. The diagram traces power from circuit 37 Y through splice…
• 1988 Ford F-250 Diesel Start & Glow Plug Wiring Diagram - EVTM Page 30
  This is page 30 of a Ford Electrical & Vacuum Troubleshooting Manual (EVTM) wiring diagram titled "START/GLOW PLUG CONTROL/RUN (DIESEL)." It shows the starting and glow plug circuit for a diesel engine with dual…
• 1988 Ford F-250 Diesel Charge/Power Distribution Wiring Diagram - EVTM Pg 22
  This is page 22 of a Ford Electrical & Vacuum Troubleshooting Manual (EVTM) titled "Charge/Power Distribution (Diesel)." It is a wiring diagram showing how battery power (circuits 37 Y and 38 BK/O) feeds the ignition…
• 1988 Ford F-250 Diesel Charge/Power Distribution Wiring Diagram - EVTM Page 21
  This is page 21 of the Ford Electrical & Vacuum Troubleshooting Manual (EVTM) covering the Charge/Power Distribution circuit for the diesel engine. The wiring diagram shows power distribution circuits 37 (Yellow) and…
• 1988 Ford F-250 Diesel Charge/Power Distribution Wiring Diagram - EVTM Pg 20
  This is page 20 of a Ford Electrical & Vacuum Troubleshooting Manual (EVTM) showing the Charge/Power Distribution circuit for a diesel F-250/Super Duty. The diagram traces power from dual batteries (LH with 0 GA red…