ECU - Electronic Control Unit Connector.
The 1991–1993 Mitsubishi 3000GT VR4 uses a multi-point injection (MPI) engine management system built around the twin-turbocharged 6G72 3.0 litre DOHC V6, mounted in the Z16A chassis with all-wheel drive. The ECU is a Mitsubishi-sourced unit that communicates with injectors, sensors, and actuators through a three-piece connector assembly (sections commonly labelled A, B, and C in the service manual terminal charts). The VR4 ECU differs from the naturally-aspirated 3000GT unit by adding boost-related control circuits and a second oxygen sensor for the twin-bank exhaust. The Dodge Stealth R/T Twin Turbo is a platform-identical rebadge and shares the same ECU hardware and connector pinout.
| Pin | name | Signal |
|---|---|---|
| 1 | Injector 1 | Speed |
| 2 | Injector 3 | Speed |
| 3 | Injector 5 | Speed |
| 14 | Injector 2 | Speed |
| 15 | Injector 4 | Speed |
| 16 | Injector 6 | Speed |
| 26 | Power Ground | Ground |
| 52 | Air Intake Temperature Sensor | Analog |
| 55 | O2 Sensor # 1 ( Right Bank) | Analog |
| 56 | O2 Sensor # 2 ( Left Bank) | Analog |
| 63 | Engine Coolant Temperature Sensor | Analog |
| 64 | Throttle Position Sensor | Analog |
| 65 | Atmospheric Pressure Sensor | Analog |
| 66 | Vehicle Speed Sensor | Speed |
| 70 | Volume Air Flow Sensor | Analog |
| 71 | Power Ground | Ground |
| 72 | Sensor Ground | Ground |
Notes
The ECU connector is a three-piece keyed unit; each section must be fully seated before the locking tab engages. Pin numbers shown correspond to the terminal chart in the 1991 service manual electrical volume and the 1993 Technical Information Manual. The VR4 application uses two oxygen sensors (one per exhaust bank) whereas the SOHC non-turbo variant uses only one. Terminal voltage checks should be performed with the ignition on and the connector attached to the ECU using a back-probe; do not force a test lead into the front of the connector as this can spread the terminal and cause an intermittent fault.
Signals
- Injector 1–6 — Low-side drive outputs to each of the six fuel injectors; the ECU grounds the injector coil to open it
- Power Ground — Main ECU power ground reference (pins 26 and 71); both must have good chassis contact
- Air Intake Temperature Sensor — Analogue input from the thermistor in the air-flow sensor housing; resistance decreases as temperature rises
- O2 Sensor #1 (Right Bank) — Analogue voltage input from the front oxygen sensor on the right (rear-facing) cylinder bank; nominally 0–1 V
- O2 Sensor #2 (Left Bank) — Analogue voltage input from the front oxygen sensor on the left (front-facing) cylinder bank; used for closed-loop fuelling on the VR4
- Engine Coolant Temperature Sensor — Analogue input from the coolant thermistor; used for cold-start enrichment and fan control
- Throttle Position Sensor — Analogue voltage input (0–5 V range) indicating throttle plate angle; used for load calculation and acceleration enrichment
- Atmospheric Pressure Sensor — Analogue input from the barometric pressure sensor; used for altitude correction of fuel and ignition maps
- Vehicle Speed Sensor — Pulsed speed signal from the transmission output; used for idle-up control and speed-density calculations
- Volume Air Flow Sensor — Analogue voltage input from the karman vortex or hot-wire mass-air sensor measuring inducted air volume
- Sensor Ground — Dedicated low-noise ground reference for all analogue sensor returns (pin 72); must not be confused with power ground