1991-1996 Subaru Impreza¶
Engine¶
Turbocharged opposed 4 cylinder EJ20G
Stock ECU¶
A lot of useful info can be found at Diagnostics and Datalogging for Subaru SVX.
ECU Pinout¶
This pinout can be partially correct for other Subaru from early 90s (with same yellow ECU connector). Like Legacy/Liberty, SVX and so on.
Connector: Hardware:OEM_connectors#76_pin
EDM connector B44 (JDM - B60)
| Terminal | Type | EDM Signal | JDM Signal | Note | Wire color |
|---|---|---|---|---|---|
| 1 | OD output | Idle air control solenoid: close end | same | ||
| 2 | OD output | Idle air control solenoid: open end | same | ||
| 3 | OD output | Wastgate control solenoid | same | ||
| 4 | OD output | Radiator fan 1 control | same | Ext relay | |
| 5 | Open Emiter output | Self shutoff control | same | +12 output to hold main relay on (serial diode protected on ECU side) | |
| 6 | OD output | Purge control solenoid valve | 5th injector relay (RA-version) | ||
| 7 | OD+Pull-up output | Ignition control #4 | same | ||
| 8 | OD+Pull-up output | Ignition control #3 | same | ||
| 9 | OD+Pull-up output | Ignition control #2 | same | ||
| 10 | OD+Pull-up output | Ignition control #1 | same | ||
| 11 | OD output | Fuel injector #3 | same | ||
| 12 | OD output | Fuel injector #2 | same | ||
| 13 | OD output | Fuel injector #1 | same | ||
| 14 | Power | GND (power supply) | same | (not sure) | |
| 15 | Power | Ignition GND | same | externaly connected to body | |
| 16 | Input | Power steering pressure switch | same | to GND | |
| 17 | OD output | Radiator fan 2 control | same | Ext relay | |
| 18 | - | No connection | same | ||
| 19 | OD output | Jakie Chan lamp | same | ||
| 20 | OD output | Pressure exchange solenoid valve | same | Used to switch pressure sensor between intake and atmosphere | |
| 21 | - | No connection | same | ||
| 22 | OD output | AC cut relay | same | ||
| 23 | OD output | Fuel pump relay | same | ||
| 24 | Power | Injectors GND | same | ||
| 25 | Power | Injectors GND | same | ||
| 26 | OD output | Fuel injector #4 | same |
EDM connector B96 (JDM B116)
| Terminal | Type | EDM Signal | JDM Signal | Note | Wire color |
|---|---|---|---|---|---|
| 1 | Input | Camshaft position sensor: signal + | same | ||
| 2 | Input | Camshaft position sensor: signal - | same | ||
| 3 | Shield | Camshaft position sensor: shield | same | ||
| 4 | Shield | Knock sensor: shield | same | ||
| 5 | Input | Knock sensor: signal | same | ||
| 6 | Input | Idle switch | ? | Throttle fully closed | |
| 7 | Tx | Subaru Select Monitor signal | same | 5V uart, 1953 baud, 8 data bits, 1 stop bit, Even Parity and no flow control | |
| 8 | Rx | Subaru Select Monitor signal | same | 5V uart, 1953 baud, 8 data bits, 1 stop bit, Even Parity and no flow control | |
| 9 | Input | AC switch | same | to gnd | |
| 10 | Input | Starter signal | same | ||
| 11 | Input | ? | Idle switch | Throttle fully closed | |
| 12 | Input | Read memory connector | same | connect to GND | |
| 13 | Input | Test connector | same | connect to GND | |
| 14 | - | No connection | same | ||
| 15 | - | No connection | same | ||
| 16 | Output 5V | Engine tachometer output | same | 2 pulses per rev |
EDM connector B95 (JDM B115)
| Terminal | Type | EDM Signal | JDM Signal | Note | Wire color |
|---|---|---|---|---|---|
| 1 | Power OUT | Throttle position switch: GND/Shield | same | ||
| 2 | Input | Throttle position switch: Signal | same | Fully closed: 4.7V, Fully opened: 0.9V | |
| 3 | Power OUT | Throttle position switch: 5V | same | 5V output | |
| 4 | Input | Crancshaft position sensor: signal + | same | ||
| 5 | Input | Crancshaft position sensor: signal - | same | ||
| 6 | Shield | Crancshaft position sensor: shield | same | ||
| 7 | - | No connection | same | ||
| 8 | - | No connection | same | ||
| 9 | - | No connection | same | ||
| 10 | Input | Neutral switch | same | ||
| 11 | Input | Vehicle speed | same | 5V level from dashboard | |
| 12 | Input | IGN signal | same |
EDM connector B43 (JDM B59)
| Terminal | Type | EDM Signal | JDM Signal | Note | Wire color |
|---|---|---|---|---|---|
| 1 | - | No connection | same | ||
| 2 | Power | Power supply | same | Through main relay | |
| 3 | Power OUT | Pressure sensor: 5V | same | 5V output | |
| 4 | Input | Pressure sensor: signal | same | ||
| 5 | Input | No connection | EGT sensor input | ||
| 6 | Input | O2 sensor: signal | same | Rich: 0.7-1.0, Leam: 0.0-0.2 | |
| 7 | Input | Engine coolant t | same | ||
| 8 | Power OUT | MAF: 12V | same | ||
| 9 | Input | MAF: signal | same | ||
| 10 | Power OUT | MAF: GND | same | ||
| 11 | Power | GND (control system) | same | ||
| 12 | Output | No connection | IP light ses (?) | ||
| 13 | Power | Power supply | same | Through main relay | |
| 14 | - | No connection | same | ||
| 15 | Power | Back-up power supply | same | Always on | |
| 16 | - | No connection | same | ||
| 17 | Input | O2 sensor: shield | same | ||
| 18 | - | No connection | same | ||
| 19 | Power OUT | MAF: shield | same | ||
| 20 | - | No connection | same | ||
| 21 | Power OUT | Pressure, coolant T, EGT sensors GND | same | ||
| 22 | Power | GND (control system) | same |
ECU connection¶
Impreza 1991+
Liberty RS 1993
Stock ECU internals¶
Output drivers:
4 x UPA1558H - 4 N-channel power MOSFETs
1 x 4AK19 - 4 N-channlel power MOSFETs (2.5 A) - seems to drive injectors
(2S)A1441 - 5A PNP transistors - seems to drive self-shutdown control output