ECU - Electronic Control Unit Connector.
The 1994–95 Ford Mustang 5.0 L (302 cu in) uses Ford’s EEC-IV (Electronic Engine Control IV) system, introduced in 1983 and fitted to Mustangs through the end of the Fox-body and into the SN95 platform. On the SN95, the Powertrain Control Module (PCM) is located in the passenger-side footwell and connects via a single 60-pin connector. Mass Air Flow metering (pin 50) is used rather than the Speed Density MAP-based strategy of 1986–87 models, and the primary oxygen sensor moves to pin 44 (versus pin 29 on Fox-body cars). The brake on/off switch input appears on pin 2, which is specific to the SN95 configuration.
| Pin | name | Signal |
|---|---|---|
| 2 | Brake Switch | Analog |
| 3 | Vehicle Speed Sensor | Speed |
| 7 | Engine Coolant Temperature Sensor | Analog |
| 25 | Intake Air Temperature Sensor | Analog |
| 43 | Secondary O2 Sensor | Analog |
| 44 | Primary O2 Sensor | Analog |
| 47 | Throttle Position Sensor | Analog |
| 50 | Mass Air Flow | Analog |
| 56 | Ignition Control Module | RPM |
| 60 | Power Ground | Ground |
Notes
- The 60-pin connector is the sole PCM harness connector; probing it directly risks bent or damaged pins — use a breakout box.
- VREF (5 V reference) on pin 26 and Signal Return ground on pin 46 are shared by the TPS (pin 47), ECT (pin 7), and ACT/IAT (pin 25) sensors.
- Keep Alive Memory power (KAPWR) is supplied on pin 1; VPWR appears on pins 37 and 57; power grounds are pins 40 and 60; case ground is pin 20.
- The T4M0 processor code was used in 1994–95 GT manual-transmission applications; automatic-transmission cars used a related code.
- A separate J3 card-edge connector on the side of the PCM (15/30 terminal, 0.1-inch spacing) is used for chip tuning and is not part of the main 60-pin harness.
Signals
- BOO (Brake On/Off) — brake switch input on pin 2; signals the PCM when the brake pedal is depressed, used for torque converter clutch release and idle speed adjustments.
- VSS (Vehicle Speed Sensor) — speed signal on pin 3; provides road speed data to the PCM for fuel and spark calculations.
- ECT (Engine Coolant Temperature) — thermistor input on pin 7; used for fuel enrichment, idle speed, and ignition timing correction relative to coolant temperature.
- ACT/IAT (Intake Air Temperature) — thermistor input on pin 25; used to correct fuel delivery for inlet air density.
- HO2S-2 (Secondary O2 Sensor) — downstream heated oxygen sensor on pin 43; used for catalyst efficiency monitoring.
- HO2S-1 (Primary O2 Sensor) — upstream heated oxygen sensor on pin 44; primary closed-loop fuelling feedback signal.
- TPS (Throttle Position Sensor) — variable-resistance input on pin 47; reports throttle plate angle to the PCM for load and acceleration calculations.
- MAF (Mass Air Flow) — frequency/voltage signal on pin 50; measures inducted air mass for fuel metering (replaces the Speed Density MAP input used on 1986–87 models).
- PIP (Profile Ignition Pickup) — RPM and crankshaft position signal from the TFI ignition module on pin 56; the fundamental timing reference for fuel and spark events.
- PWR GND (Power Ground) — primary power ground on pin 60 (also pin 40); reference return for PCM power supply circuits.
References
- Ford Electrical & Vacuum Troubleshooting Manual (EVTM), Mustang 5.0 L — Ford Motor Company (FPS-12121-92); available through Forel Publishing under Ford licence.
- SAE Technical Paper 820900 — EEC-IV: Tomorrow’s Electronic Engine Controls Today — Hagen & Wilkie, Ford Motor Company / SAE International, 1982.