1986-95 Ford V8 Truck Speed Density EEC-IV Wiring Diagram - VSS & Sensor Pins
Reference · 1987-1991 BroncoAll 175 wiring diagrams
RJM Speed Density EEC-IV wiring schematic for 1986-95 Ford V8 trucks: ECT, ACT, TPS, MAP, VSS, HEGO sensors and 8 injectors mapped to EEC pins, ground codes and EFI relay.
Part of 1987-1991 Ford Bronco Wiring Diagrams
This is a wiring/pin-out schematic for the Ford EEC-IV speed density fuel injection system used on 1986-95 V8 trucks, produced by RJM Injection Technologies (fordfuelinjection.com, copyright 2004). It shows connector drawings and EEC pin numbers for the main engine management sensors and actuators: Engine Coolant Temp sensor (ECT, pin 7), Air Charge Temp sensor (ACT, pin 25), Throttle Position Sensor (TPS, pin 47), MAP sensor (pin 45), HEGO oxygen sensor (pin 29), Vehicle Speed Sensor (VSS+ pin 3, VSS− pin 6), Idle Air Bypass/ISC (pin 21), Self-Test connector (STO/MIL pin 17), Self-Test Input (STI pin 48), and the Check Engine Light (MIL). Injector banks are shown: cylinders 1, 4, 5, 8 on INJ 58 and cylinders 2, 3, 6, 7 on INJ 59. Additional connections include NDS 30 (auto trans only), FPM 8 to fuel pump, SIG RTN 46, VREF 26, grounds (CASE GND 20, PWR GND 40, HEGO GND 49, PWR GND 60), and power feeds via the EFI relay to EEC pins 37 and 57 (VPWR). The uploader has highlighted the VSS circuit in blue and its reference ground point in red, matching the filename "VSS Reference Ground."
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Frequently asked questions
- What EEC-IV pins does the Vehicle Speed Sensor (VSS) use on a 1986-95 Ford speed density V8 truck?
- VSS+ goes to pin 3 and VSS− goes to pin 6; the VSS− side ties to a reference ground (highlighted in the diagram).
- Which injectors are grouped on each EEC injector driver pin?
- Cylinders 1, 4, 5, and 8 connect to INJ pin 58, while cylinders 2, 3, 6, and 7 connect to INJ pin 59.
- What pin numbers are used for the main engine sensors?
- ECT is pin 7, ACT is pin 25, TPS is pin 47, MAP is pin 45, and the HEGO oxygen sensor is pin 29.
- Which EEC pins provide power and ground?
- VPWR comes in on EEC pins 37 and 57 via the EFI relay; grounds are CASE GND 20, PWR GND 40, HEGO GND 49, and PWR GND 60.
- What are the self-test connector pins for diagnostics?
- STO/MIL is pin 17 on the self-test connector, and the self-test input (STI) is pin 48.
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