2002 - 2004 Subaru Impreza WRX ECU

The Engine Control Module (ECM) fitted to the 2002–2004 Subaru Impreza WRX (chassis GD/GG) manages the horizontally-opposed 2.0 L H4DOTC turbocharged four-cylinder engine. Five multi-pin connectors — designated B134, B135, B84, B136 and B137 in the Fuji Heavy Industries factory service manuals — link the ECM to sensors, actuators and vehicle systems. The ECM is located under the steering column, inside the instrument panel lower trim panel on all affected models. The 2005 Saab 9-2X Aero, a rebadged US-market WRX, shares the same engine harness and ECM connector arrangement.

ECU - Electronic Control Unit Connector.

Connector D

Connector C

Connector E

Connector B

Connector A

Notes

The ECM connector family used on the 2002–2004 WRX (H4DOTC turbo) comprises five connectors: B134 (28-pin), B135 (22-pin), B84 (31-pin), B136 (17-pin) and B137 (24-pin). The page table letters A–E correspond to this connector family as wired by the factory harness. The non-turbocharged (NA) Impreza ECM uses a different subset of connectors (B134, B135, B136 only) and must not be substituted. Disconnecting the battery before removing the ECM is mandatory; fitting an incorrect-specification ECM will damage the fuel injection system.

Signals

• Injector #1 — fuel injector driver output for cylinder 1 (OEM ref. B84-1)
• Injector #2 — fuel injector driver output for cylinder 2 (OEM ref. B137-6)
• Injector #3 — fuel injector driver output for cylinder 3 (OEM ref. B137-5)
• Injector #4 — fuel injector driver output for cylinder 4 (OEM ref. B137-4)
• Power Ground — ECM chassis ground reference
• Power Ground (Injector) — dedicated ground return for injector drivers
• Power Ground (Coils) — dedicated ground return for ignition coil drivers
• O2 Sensor Signal (Front) — analogue voltage from the front (upstream) air/fuel ratio sensor; signal lines on OEM connectors B84-5 and B84-4
• O2 Sensor Signal (Rear) — analogue voltage from the rear (downstream) oxygen sensor (OEM ref. B135-18)
• Tach Signal — engine speed pulse output derived from ignition coil firing events
• Mass Air Flow Sensor — analogue voltage from the hot-wire MAF sensor (OEM ref. B136-13); shielded line (B136-8) and sensor ground (B136-7) are separate pins
• Mass Air Flow Sensor Ground — signal ground for the MAF sensor
• Throttle Position Sensor — analogue voltage proportional to throttle plate angle (OEM ref. B135-7); sensor power supply 5 V on B135-9; sensor ground on B135-19
• Manifold Atmospheric Pressure Sensor — analogue pressure signal used for boost and load calculation
• Engine Coolant Temperature Sensor — NTC thermistor signal (OEM ref. B135-17); ground on B135-26
• Sensor Ground — common reference ground for analogue sensors on connector B
• Intake Air Temperature Sensor — NTC thermistor embedded in or near the MAF sensor body (OEM ref. B135-27)
• Vehicle Speed Sensor — vehicle speed pulse input to the ECM (OEM ref. B134-1)

References

• 2004 Impreza Service Manual — Engine Section 2 (Pub. No. G1870GE3)
• 2004 Impreza Service Manual — Wiring System Section (Pub. No. G1870GE7) — Part 3
• 2004 Impreza Service Manual — Wiring System Section (Pub. No. G1870GE7) — Part 1
• 2002 Impreza Service Manual — Engine 2 Section / DOHC Turbo (Pub. No. G1830BE3)
• 2002 Impreza Service Manual — Wiring System Section (Pub. No. G1830BE7)

Category:Car Connectors