The Ford EEC-IV (Electronic Engine Control IV) system, introduced in 1983, governs fuel and ignition management on the 1986–1987 Fox-body Mustang 5.0 L (302 cu in). It uses a single 60-pin module connector and an Intel 8061 (8096-family) microcontroller. These model years employ Speed Density control, relying on a Manifold Absolute Pressure (MAP) sensor at pin 45 rather than the Mass Air Flow measurement adopted from 1988 onwards. A breakout box should be used when probing the connector, as direct test-lead insertion risks pin damage.
ECU - Electronic Control Unit Connector.
| Pin | Name | Signal Type |
|---|---|---|
| 7 | Engine Coolant Temperature Sensor | Analog |
| 25 | Intake Air Temperature Sensor | Analog |
| 29 | Primary O2 Sensor | Analog |
| 40 | Power Ground | Ground |
| 43 | Secondary O2 Sensor | Analog |
| 45 | MAP Sensor | Analog |
| 47 | Throttle Position Sensor | Analog |
| 56 | Ignition Control Module | RPM |
Notes
The EEC-IV module connector carries 60 pins in total; only a subset is listed in the table above. Key power and reference pins not shown in the table include: KAPWR (Keep Alive Memory Power) on pin 1; VPWR (battery power) on pins 37 and 57; PWR GND on pins 40 and 60; CASE GND on pin 20; and the 5 V sensor reference (VREF) on pin 26, shared by the TPS, ECT, and ACT sensors. Signal Return ground is on pin 46. The MAP sensor on pin 45 is specific to these 1986–1987 Speed Density calibration vehicles; 1988 and later Mustang 5.0 L models deleted pin 45 in favour of a Mass Air Flow input on pin 50.
Signals
- Engine Coolant Temperature Sensor (pin 7) — analogue voltage signal from the ECT thermistor; shared 5 V VREF (pin 26) and Signal Return (pin 46).
- Intake Air Temperature Sensor (pin 25) — analogue voltage signal from the ACT/IAT thermistor, also using VREF and Signal Return.
- Primary O2 Sensor (pin 29) — analogue signal from the upstream (pre-catalyst) heated exhaust-gas oxygen sensor used for closed-loop fuelling.
- Power Ground (pin 40) — PWR GND; one of two power-ground pins (the other being pin 60).
- Secondary O2 Sensor (pin 43) — analogue signal from the downstream oxygen sensor.
- MAP Sensor (pin 45) — Manifold Absolute Pressure sensor input; present on 1986–1987 Speed Density ECUs only. The EEC-IV calculates air-charge from MAP, ECT, and ACT rather than direct mass-airflow measurement.
- Throttle Position Sensor (pin 47) — analogue voltage proportional to throttle-plate angle; uses VREF (pin 26) and Signal Return (pin 46).
- Ignition Control Module (pin 56) — PIP (Profile Ignition Pickup) pulse from the TFI (Thick Film Integrated) ignition module; provides engine-speed and crank-position data to the EEC-IV.
References
- Ford Electrical & Vacuum Troubleshooting Manual, Mustang 5.0 L, part no. FPS-12121-86 / 0336-503-86, Ford Motor Company, 1986
- SAE Technical Paper 820900 — EEC-IV: Tomorrow’s Electronic Engine Controls Today