Engine Controls - Pin Voltage Charts: Introduction
Pin voltage charts are supplied to reduce diagnostic time. Checking pin voltages at the ECU determines whether it is receiving and transmitting proper voltage signals. Charts may also help determine if ECU harness is open or shorted.
NOTE:
Unless stated otherwise in testing procedures, perform all voltage tests using a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance. Voltage readings may vary slightly due to battery condition or charging rate.
- ECU circuits are checked at ECU connector under one or more of the following conditions: ignition off, ignition on and engine off, or ignition on and engine running. Test between indicated terminal and a good body ground. Use wire color to help identify terminal. See appropriate ECU PIN SPECIFICATIONS table. To test pin voltage, carefully backprobe terminal at harness side of ECU connector. See Fig 1
.
- If resistance or voltage is not as specified, test and repair or replace circuit or affected component. Retest circuit to verify repair has been made. Unless stated otherwise, perform all tests with ECU harness connected.
Courtesy of SUBARU OF AMERICA, INC. ECU PIN SPECIFICATIONS - CONNECTOR F119
| ECU Terminal No. (Wire Color) |
Circuit |
Condition |
Volts Or Ohms |
| 1(Black/Red) |
Ground |
Ignition Off |
10 Ohms Less |
| 2(Red/Yellow) |
Vacuum Pressure Sensor |
N/A |
N/A |
| 3(Red) |
Crank Angle Signal(+) |
Ignition Off |
Infinite |
| 3(Red) |
Crank Angle Signal(+) |
Engine Cranking |
1-3V |
| 4(White) |
Crank Angle Signal (-) |
Ignition Off |
Infinite |
| 5(Black) |
Cylinder Distinction Signal (+) |
Ignition Off |
Infinite |
| 6(Green) |
Cylinder Distinction Signal (-) |
Ignition Off |
Infinite |
| 7(Shield) |
Crank Angle/ Cyl. Distinction |
Ignition Off |
10 Ohms or Less |
| 8(White/Red) |
High Altitude Signal |
N/A |
N/A |
| 9(Brown/Black) |
Torque Signal |
N/A |
N/A |
| 10(Brown/White) |
Coolant Temperature Signal |
N/A |
N/A |
| 11(White) |
Injector No. 3 |
Ignition On |
8V Or More |
| 12(White/Yellow) |
Injector No. 1 |
Ignition On |
8V Or More |
| 13(Black/Blue) |
Ground |
Ignition Off |
10 Ohms Or Less |
| 14 |
N/A |
N/A |
N/A |
| 15(Green/White) |
A/C Cut Signal |
N/A |
N/A |
| 16 |
N/A |
N/A |
N/A |
| 17 |
N/A |
N/A |
N/A |
| 18(Blue/Black) |
Fuel Pump |
N/A |
N/A |
| 19(Light Green) |
Check Engine Light |
Ignition On |
9V Or More |
| 20(Orange) |
Shift Indicator Light |
N/A |
N/A |
| 21(Yellow/White) |
Ignition Signal |
Ignition Off |
Infinite |
| 21(Yellow/White) |
Ignition Signal |
Engine Cranking |
1-3V |
| 22(Blue/Red) |
Canister Purge Control |
Ignition Off |
Infinite |
| 22(Blue/Red) |
Canister Purge Control |
Ignition On |
2.5-8V (Alternating) |
| 23(Brown/Red) |
A/C Compressor |
N/A |
N/A |
| 24(Green/Yellow) |
ISC Signal |
Ignition Off |
Infinite |
| 24(Green/Yellow) |
ISC Signal |
Ignition On |
8V Or More |
| 25(White/Green) |
Injector No. 2 |
Ignition On |
8V Or More |
| 26(Black/Blue) |
Ground |
Ignition Off |
10 Ohms Or Less |
ECU PIN SPECIFICATIONS - CONNECTOR F120
| ECU Terminal No. (Wire Color) |
Circuit |
Condition |
Volts Or Ohms |
| 1(Red) |
Power |
Ignition On |
9V Or More |
| 2(White/Blue) |
Memory Back-Up Power |
Ignition On |
9V Or More |
| 3(Light Green) |
Ignition Monitor |
Engine Cranking |
1-3V |
| 3(Light Green) |
Ignition Monitor |
Ignition Off |
Infinite |
| 4(Light Green/ Blue) |
Speed Sensor |
Ignition On |
0.25V-2.5V (Alternating) |
| 5(Yellow/Blue) |
Clutch Switch |
Ignition Off |
Infinite |
| 5(Yellow/Blue) |
Clutch Switch |
Ignition On |
8V Or More (Gear Select In "N") |
| 5(Yellow/Blue) |
Clutch Switch |
Ignition On |
8V Or More |
| 5(Yellow/Blue) |
Clutch Switch |
Ignition On |
1V Or Less (Clutch Released) |
| 5(Yellow/Blue) |
Clutch Switch |
Ignition On |
8V Or More (Clutch Applied) |
| 6(Blue/White) |
Idle Switch |
Ignition Off |
Infinite |
| 6(Blue/White) |
Idle Switch |
Ignition On |
1V Or Less |
| 7(Blue/Green) |
Serial Monitor RX |
N/A |
N/A |
| 8(Yellow) |
Serial Monitor Clock |
N/A |
N/A |
| 9(Green/Blue) |
Serial Monitor TX |
N/A |
N/A |
| 10(Black/Red) |
Ground |
Ignition Off |
10 Ohms Or Less |
| 11(Green/White) |
Blower Fan Signal |
Ignition On |
8V Or More (Fan Off) |
| 11(Green/White) |
Blower Fan Signal |
Ignition On |
8V Or More (Fan in 3rd Position) |
| 12(Red) |
Power |
Ignition On |
9V Or More |
| 13 |
N/A |
N/A |
N/A |
| 14 (Blue) |
A/C Signal |
N/A |
N/A |
| 15(Green/Black) |
Radiator Fan Signal |
Ignition Off |
Infinite |
| 15(Green/Black) |
Radiator Fan Signal |
Ignition On |
1V Or Less (Fan On) |
| 15(Green/Black) |
Radiator Fan Signal |
Ignition On |
8V Or More (Fan Off) |
| 16(Green/Red) |
Power Switch |
Ignition Off |
Infinite |
| 16(Green/Red) |
Power Switch |
Ignition On |
8V (Throttle Fully Closed) |
| 16(Green/Red) |
Power Switch |
Ignition On |
1V (Throttle Fully Open) |
| 17(Black/White) |
Starter Switch |
Engine Cranking |
8V Or More |
| 18(Blue/Yellow) |
Rear Defogger Switch |
Ignition On |
2V Or Less (Rear Defogger Off) |
| 18(Blue/Yellow) |
Rear Defogger Switch |
Ignition On |
8V Or More (Rear Defogger On) |
| 19 |
N/A |
N/A |
N/A |
| 20(Blue/White) |
Headlight: High Signal |
Ignition On |
8V Or More (Headlights Off) |
| 20(Blue/White) |
Headlight:High Signal |
Ignition On |
8V Or More (Headlights High) |
| 21(Red/Yellow) |
Headlight: Low Signal |
Ignition On |
8V Or More (Headlights Off) |
| 21(Red/Yellow) |
Headlight: Low Signal |
Ignition On |
8V Or Less (Headlights Low) |
| 22 |
N/A |
N/A |
N/A |
ECU PIN SPECIFICATIONS - CONNECTOR F121
| ECU Terminal No. (Wire Color) |
Circuit |
Condition |
Volts Or Ohms |
| 1(Black/Green) |
Ground |
Ignition Off |
10 Ohms Or Less |
| 2(Black/Green) |
Ground |
Ignition Off |
10 Ohms Or Less |
| 3(Yellow/Red) |
Vacuum Pressure Sensor |
N/A |
N/A |
| 4(Black) |
Oxygen Sensor |
Engine Idling |
0.5-4.5 (Alternating) |
| 5(White/Black) |
Coolant Temperature Sensor |
Ignition Off |
Infinite |
| 6(White/Blue) |
Air Temperature Sensor |
Ignition Off |
Infinite |
| 7(Shield) |
Oxygen Sensor |
N/A |
N/A |
| 8(Yellow/Black) |
High Altitude Signal |
N/A |
N/A |
| 9(Light Green/ White) |
Read Memory Connector |
Ignition Off |
One Ohm |
| 9(Light Green/ White) |
Read Memory Connector |
Ignition Off |
Infinite |
| 10(Brown) |
Test Mode Connector |
Ignition Off |
One Ohm |
| 10(Brown) |
Test Mode Connector |
Ignition Off |
Infinite |
| 11(Black/Red) |
Transmission ID |
Ignition Off |
One Ohm Or Less (A/T) |
| 11(Black/Red) |
Transmission ID |
Ignition Off |
Infinite(M/T) |
| 12(Black/Blue) |
Vehicle Identification |
Ignition Off |
One Ohm Or Less (Calif.) |
| 12(Black/Blue) |
Vehicle Identification |
Ignition Off |
Infinite (Federal) |
| 13 |
N/A |
N/A |
N/A |
| 14(Black/Red) |
FWD Vehicle ID |
Ignition Off |
Infinite(FWD) |
| 14(Black/Red) |
4WD Vehicle ID |
Ignition Off |
One Ohm Max. (4WD) |
| 15 |
N/A |
N/A |
N/A |
| 16 |
N/A |
N/A |
N/A |