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Home >> Subaru >> 2017 >> WRX STI >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System (Diagnostics - Introduction) (2.5L) >> Engine Control Module (ECM) I/O Signal >> Electrical Specification
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Electrical Specification

Fig 1: Engine Control Module (ECM) I/O Signal Connector Terminals
G10290804Courtesy of SUBARU OF AMERICA, INC.
Description Connector No. Terminal No. Signal (V) Note
Ignition SW ON (Engine OFF) Engine ON (Idling)
Crankshaft position sensor (+) signal B137 17 0 -7 - +7 *1: Waveform
(-) signal B137 25 0 0 -
Shield B137 31 0 0 -
Front oxygen (A/F) sensor (+) signal B136 19 2.8 - 3.2 2.8 - 3.2 -
(-) signal B136 18 2.4 - 2.7 2.4 - 2.7 -
Rear oxygen sensor Signal B136 20 0 0 - 0.9 -
Oxygen sensor Shield B136 9 0 0 -
Front oxygen (A/F) sensor heater Signal 1 B136 6 - - Waveform
Signal 2 B136 5 - - Waveform
Rear oxygen sensor heater signal B135 6 Battery voltage Battery voltage Waveform
Engine coolant temperature sensor Signal B137 22 1 - 1.4 1 - 1.4 -
Air flow sensor (+) signal B136 22 - 0.3 - 4.5 -
Shield B136 10 0 0 -
Ground B136 11 0 0 -
Intake air temperature sensor signal B136 31 0.3 - 4.6 0.3 - 4.6 -
Wastegate control solenoid valve B134 33 0 or battery voltage 0 or battery voltage Waveform
Starter switch B136 16 0 0 Model without push button start Cranking: Battery voltage Model with push button start Cranking: Waveform
Accessory cut request B135 32 Battery voltage Battery voltage Model with push button start Cranking: 0
Starter switch 2 B136 27 0 0 Model with push button start Cranking: Battery voltage
Starter cut relay B135 34 0 0 Model with push button start Cranking: Battery voltage
Ignition switch B136 30 Battery voltage Battery voltage -
Neutral position switch B136 35 ON: 0 OFF: Battery voltage ON: 0 OFF: Battery voltage -
Delivery mode switch B136 34 Battery voltage Battery voltage When connected: 0
Knock sensor Signal B137 2 2.45 - 2.55 2.45 - 2.55 -
Shield B137 8 0 0 -
Back-up power supply B136 2 Battery voltage Battery voltage Ignition switch "OFF": Battery voltage
Control module power supply B136 1 Battery voltage Battery voltage -
B137 7 Battery voltage Battery voltage -
Sensor power supply B134 19 5 5 -
B135 22 5 5 -
Ignition control #1 B134 21 0 0 or 5 Waveform
#2 B134 22 0 0 or 5 Waveform
#3 B134 31 0 0 or 5 Waveform
#4 B134 32 0 0 or 5 Waveform
Fuel injector #1 B134 10 Battery voltage 0 or battery voltage Waveform
#2 B134 11 Battery voltage 0 or battery voltage Waveform
#3 B134 12 Battery voltage 0 or battery voltage Waveform
#4 B134 13 Battery voltage 0 or battery voltage Waveform
Fuel pump control unit Control B136 33 0 or 5 0 or 5 Waveform
Diagnostic signal B135 10 Battery voltage Battery voltage -
A/C relay control B135 35 ON: 0.5 or less OFF: Battery voltage ON: 0.5 or less OFF: Battery voltage -
A/C switch B136 29 ON: Battery voltage OFF: 0 ON: Battery voltage OFF: 0 Manual A/C model
Blower fan switch B135 19 ON: 0 OFF: Battery voltage ON: 0 OFF: Battery voltage Manual A/C model
Main fan relay control B135 12 ON: 0.5 or less OFF: Battery voltage ON: 0.5 or less OFF: Battery voltage -
Sub fan relay control B135 11 ON: 0.5 or less OFF: Battery voltage ON: 0.5 or less OFF: Battery voltage -
Engine speed output B135 15 - 0 or battery voltage Model with push button start Waveform
Purge control solenoid valve 1 B137 6 ON: 1 or less OFF: Battery voltage ON: 1 or less OFF: Battery voltage Waveform
Purge control solenoid valve 2 B137 15 ON: 1 or less OFF: Battery voltage ON: 1 or less OFF: Battery voltage Waveform
Manifold absolute pressure sensor Signal B137 20 1.7 - 2.4 1.1 - 1.6 -
Power steering oil pressure switch B137 28 Battery voltage ON: 0 OFF: Battery voltage -
SSM/GST communication line B135 14 - - -
Intake camshaft position sensor RH B137 24 0 or 5 0 or 5 *1: Waveform
Intake camshaft position sensor LH B137 16 0 or 5 0 or 5 *1: Waveform
Exhaust camshaft position sensor RH B137 23 0 or 5 0 or 5 *1: Waveform
Exhaust camshaft position sensor LH B137 29 0 or 5 0 or 5 *1: Waveform
Camshaft position sensor ground B137 30 0 0 -
Electronic Throttle Main B134 18 Approx. 0.9 Approx. 0.6 - 0.7 Fully closed: Approx. 0.6 Fully open: Approx. 4.0
Sub B134 28 Approx. 1.7 Approx. 1.5 - 1.6 Fully closed: Approx. 1.5 Fully open: Approx. 4.2
(+) Electronic throttle control motor B134 2 Duty waveform Duty waveform Drive frequency: 500 Hz
(-) Electronic throttle control motor B134 1 Duty waveform Duty waveform Drive frequency: 500 Hz
Electronic throttle control motor power supply B135 7 Battery voltage Battery voltage -
Electronic throttle control motor relay B135 17 0 0 -
Intake oil flow control solenoid valve RH (+) signal B134 34 0 0 or battery voltage -
(-) signal B134 27 0 0 -
Intake oil flow control solenoid valve LH (+) signal B134 17 0 0 or battery voltage -
(-) signal B134 16 0 0 -
Exhaust oil flow control solenoid valve RH (+) signal B134 7 0 0 or battery voltage -
(-) signal B134 15 0 0 -
Exhaust oil flow control solenoid valve LH (+) signal B134 5 0 0 or battery voltage -
(-) signal B134 14 0 0 -
Accelerator pedal position sensor Main sensor signal B135 23 Fully closed: 0.4 - 1 Fully opened: 2.4 - 3.7 Fully closed: 0.4 - 1 Fully opened: 2.4 - 3.7 -
Main power supply B135 21 5 5 -
Ground (main sensor) B135 29 0 0 -
Sub sensor signal B135 31 Fully closed: 0.3 - 1.1 Fully opened: 2.3 - 3.8 Fully closed: 0.3 - 1.1 Fully opened: 2.3 - 3.8 -
Starter relay B135 26 ON: 0 OFF: Battery voltage ON: 0 OFF: Battery voltage ON: Cranking
A/C middle pressure switch B136 7 ON: 0 OFF: Battery voltage ON: 0 OFF: Battery voltage -
Clutch switch B135 9 When clutch pedal is depressed: 0 When clutch pedal is released: Battery voltage When clutch pedal is depressed: 0 When clutch pedal is released: Battery voltage -
Brake switch 1 (Brake switch) B136 15 When brake pedal is depressed: 0 When brake pedal is released: Battery voltage When brake pedal is depressed: 0 When brake pedal is released: Battery voltage -
Brake switch 2 (Stop light switch) B136 3 When brake pedal is depressed: Battery voltage When brake pedal is released: 0 When brake pedal is depressed: Battery voltage When brake pedal is released: 0 -
Cruise control command switch B136 12 When operating nothing: 3.5 - 4.5 When operating RES/ACC: 2.5 - 3.5 When operating SET/COAST: 0.5 - 1.5 When operating CANCEL: 0 - 0.5 When operating nothing: 3.5 - 4.5 When operating RES/ACC: 2.5 - 3.5 When operating SET/COAST: 0.5 - 1.5 When operating CANCEL: 0 - 0.5 -
Cruise control main switch B136 13 ON: 0 OFF: 5 ON: 0 OFF: 5 -
Immobilizer signal B135 25 - - -
CAN communication (Hi) B136 17 - - -
CAN communication (Lo) B136 28 - - -
Blow-by leak diagnosis B137 12 0 0 At the time of open circuit (fault): 5
Tumble generator valve position sensor signal RH B137 11 Fully closed: 0.4 - 1.2 Fully opened: 2.8 - 4.6 Fully closed: 0.4 - 1.2 Fully opened: 2.8 - 4.6 -
Tumble generator valve position sensor signal LH B137 10 Fully closed: 0.4 - 1.2 Fully opened: 2.8 - 4.6 Fully closed: 0.4 - 1.2 Fully opened: 2.8 - 4.6 -
Tumble generator valve RH closed B134 26 Waveform Waveform -
Tumble generator valve LH closed B134 24 Waveform Waveform -
Tumble generator valve RH open B134 25 Waveform Waveform -
Tumble generator valve LH open B134 23 Waveform Waveform -
Secondary air pipe pressure sensor Signal B137 9 2.2 - 2.8 2.2 - 2.8 When secondary air is inducted: 3.2 - 4.9
Secondary air combination valve relay 1 B135 8 ON: 0 OFF: Battery voltage ON: 0 OFF: Battery voltage -
Secondary air combination valve relay 2 B135 20 ON: 0 OFF: Battery voltage ON: 0 OFF: Battery voltage -
Secondary air pump relay B135 27 ON: 0 OFF: Battery voltage ON: 0 OFF: Battery voltage -
Self-shutoff control B135 13 Battery voltage Battery voltage -
Leak check valve assembly Switching valve B135 4 Battery voltage Battery voltage Operating: 0
Pressure sensor B136 21 1 - 4 1 - 4 When ignition switch is turned to ON: atmospheric pressure
Vacuum pump B137 27 Battery voltage Battery voltage Operating: 0
Ground Sensor B134 29 0 0 -
B135 30 0 0 -
Engine 1 B134 6 0 0 -
Engine 2 B134 4 0 0 -
Engine 3 B134 3 0 0 -
Engine 4 B137 1 0 0 -
Engine 5 B137 3 0 0 -
Body B136 4 0 0 -

Measuring condition: 

NOTE:
  • Perform measurement after warming up the engine.
  • For measurement of the waveform of the crankshaft position sensor, we recommend using the DST-i oscilloscope function or a general oscilloscope.
  • Place the shift lever in neutral position.
  • Turn the A/C to OFF.
  • Turn all the accessory switches to OFF.
  • Waveforms vary depending on a measurement environment and vehicle condition.

*1: Waveform

Fig 2: Crankshaft Position Sensor Signal Waveform
G11574174Courtesy of SUBARU OF AMERICA, INC.
Measured terminal Crankshaft position sensor (+) signal (B137) No. 17 (+) - Engine ground 3 (B134) No. 3 (-):
Intake camshaft position sensor RH (B137) No. 24 (+) - Engine ground 3 (B134) No. 3 (-):
Intake camshaft position sensor LH (B137) No. 16 (+) - Engine ground 3 (B134) No. 3 (-):
Exhaust camshaft position sensor RH (B137) No. 23 (+) - Engine ground 3 (B134) No. 3 (-):
Exhaust camshaft position sensor LH (B137) No. 29 (+) - Engine ground 3 (B134) No. 3 (-):
Measuring condition While engine idling
Fig 3: Electronic Throttle Control Circuit Diagram (1 Of 4)
G10265775Courtesy of SUBARU OF AMERICA, INC.
Fig 4: Electronic Throttle Control Circuit Diagram (2 Of 4)
G11574176Courtesy of SUBARU OF AMERICA, INC.
Fig 5: Electronic Throttle Control Circuit Diagram (3 Of 4)
G11574177Courtesy of SUBARU OF AMERICA, INC.
Fig 6: Electronic Throttle Control Circuit Diagram (4 Of 4)
G10265778Courtesy of SUBARU OF AMERICA, INC.