ECU - Electronic Control Unit Connector.
The Ford EEC-IV (Electronic Engine Control IV) system, introduced in 1983, governs the fuel injection and ignition management on 5.0 L (302 cu in) Fox-body Mustangs from 1988 through 1993. All signals pass through a single 60-pin connector on the EEC-IV module, which is built around an Intel 8061 (8096-family) microcontroller. From 1988 onwards these cars employ Mass Air Flow (MAF) measurement rather than the Speed Density (MAP-based) strategy used in earlier 1986–1987 models; the A9L processor code was standard fitment on 1989–1993 five-speed manual cars.
| Pin | name | Signal |
|---|---|---|
| 3 | Vehicle Speed Sensor | Speed |
| 7 | Engine Coolant Temperature Sensor | Analog |
| 25 | Intake Air Temperature Sensor | Analog |
| 29 | Primary O2 Sensor | Analog |
| 43 | Secondary O2 Sensor | Analog |
| 47 | Throttle Position Sensor | Analog |
| 50 | Mass Air Flow | Analog |
| 56 | Ignition Control Module | RPM |
Notes
The EEC-IV module uses a single 60-pin connector; pins are numbered on the connector body. Probing the connector directly risks terminal damage — a breakout box should be used for diagnosis. VPWR (battery voltage) is supplied on pins 37 and 57; Keep Alive Memory power (KAPWR) is on pin 1. Power grounds are on pins 40 and 60; case ground is on pin 20. The 5 V reference (VREF) on pin 26 and signal return ground on pin 46 are shared by the TPS, ECT, and ACT sensors. A separate card-edge J3 test port on the side of the module (15/30 terminals, 0.1-inch spacing) is used for chip tuning and is not part of this 60-pin harness connector.
Signals
- VSS — Vehicle Speed Sensor (pin 3); frequency signal proportional to road speed
- ECT — Engine Coolant Temperature sensor (pin 7); analogue voltage, shared VREF/signal-return with TPS and ACT
- ACT/IAT — Intake Air Temperature sensor (pin 25); analogue voltage input
- O2 — Primary heated oxygen sensor (pin 29); analogue voltage (0–1 V) used for closed-loop fuel trim
- O2S — Secondary oxygen sensor (pin 43); analogue voltage, downstream of catalyst
- TPS — Throttle Position Sensor (pin 47); analogue voltage, VREF-referenced
- MAF — Mass Air Flow sensor (pin 50); analogue or frequency signal measuring inducted air mass; replaces the MAP/Speed Density input used on 1986–1987 models
- PIP — Profile Ignition Pickup (pin 56); digital RPM signal from the TFI ignition module, used for ignition timing and injector synchronisation
References
- Ford Electrical & Vacuum Troubleshooting Manual (EVTM), Mustang 5.0 L — Ford Motor Company, part nos. FPS-12121-88 (1988) and FPS-12121-92 (1992); available through Forel Publishing
- SAE Technical Paper 820900 — EEC-IV: Tomorrow’s Electronic Engine Controls Today — SAE International (Hagen & Wilkie, Ford Motor Co., 1982)