ECU - Electronic Control Unit Connector.
The third-generation Mitsubishi Eclipse (D52A chassis, 2000–2002) uses Mitsubishi’s Multiport Fuel Injection (MFI) engine management system. Two distinct ECU units were fitted: one for the 4G64 2.4 L SOHC four-cylinder (RS/GS models) and one for the 6G72 3.0 L SOHC V6 (GT/GTS/Spyder GT models), each with its own connector pinout. The 3G Eclipse was front-wheel drive only, and the Spyder convertible body style used the same ECU hardware as the hardtop GT. Terminal inspection procedures in the factory service manual list the expected voltage or resistance for each pin under defined operating conditions.
| Pin | name | Signal |
|---|---|---|
| 10 | Ignition Control Module | RPM |
| 13 | Power Ground | Ground |
| 58 | Tachometer Output | Speed |
| 72 | Intake Air Temperature Sensor | Analog |
| 73 | MAP Sensor | Analog |
| 75 | Primary O2 Sensor | Analog |
| 76 | Secondary O2 Sensor | Analog |
| 83 | Engine Coolant Temperature Sensor | Analog |
| 84 | Throttle Position Sensor | Analog |
| 86 | Vehicle Speed Sensor | Speed |
| 91 | Power Ground | Ground |
Notes
The 4G64 and 6G72 ECU units are not interchangeable; their connector housings and pin assignments differ despite sharing the same model generation. The full terminal voltage check tables for both units, including injector, sensor, ignition, idle control, and diagnostic pins, are contained in factory service manual Groups 13A (4G64) and 13B (6G72). Wiring harness routing and circuit diagrams for both engines are covered in Group 90 of the same manual.
Signals
- Ignition Control Module — RPM signal output to the ignition control module; used for timing reference.
- Power Ground (pins 13, 91) — chassis ground reference for ECU power supply circuits.
- Tachometer Output — engine speed signal routed to the instrument cluster tachometer.
- Intake Air Temperature Sensor — analogue voltage from the IAT sensor; ECU uses this to correct fuel delivery for inlet air density.
- MAP Sensor — manifold absolute pressure signal; primary load input for the MFI fuel calculation.
- Primary O2 Sensor — analogue voltage from the upstream (pre-catalyst) oxygen sensor; used for closed-loop fuelling.
- Secondary O2 Sensor — analogue voltage from the downstream (post-catalyst) oxygen sensor; used for catalyst efficiency monitoring.
- Engine Coolant Temperature Sensor — analogue voltage from the ECT sensor; used for warm-up enrichment and fan control.
- Throttle Position Sensor — analogue voltage indicating throttle plate angle; used for acceleration enrichment and idle detection.
- Vehicle Speed Sensor — pulse signal from the VSS; used for speed-dependent idle control and diagnostics.