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 with ignition off, with ignition on and engine off, and/or with ignition on and engine running. Test between indicated terminal and body ground. See ECU PIN SPECIFICATIONS (LOYALE) table. See Fig 1
and Fig 2
. Use wire color to help identify terminal. See WIRING COLOR CODE table.
- To test pin voltage, carefully backprobe terminal at harness side of ECU connector. 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.
WIRING COLOR CODE
| Color Code |
Wire Color |
| B |
Black |
| Br |
Brown |
| G |
Green |
| Gr |
Gray |
| L |
Blue |
| Lg |
Light Green |
| R |
Red |
| W |
White |
| Y |
Yellow |
Courtesy of SUBARU OF AMERICA, INC.
Courtesy of SUBARU OF AMERICA, INC. ECU PIN SPECIFICATIONS
| ECU Terminal No. (Wire Color) |
Ignition Switch: |
Volts Or Ohms |
| 1 (Blue/Green) |
On |
0-1V |
| 4 (Blue/Red) |
On |
0-10V |
| 5 (Green/Blue) |
On |
0-10V |
| 8 (White) |
Eng. On |
.1-.5V |
| 9 (Black) |
Off |
0-9 Ohms |
| 13 (Yellow/Red) |
On |
10-12V |
| 14 (Yellow/Green)
A/T Or M/T In "N" A/T Or M/T Any Gear |
Off |
Infinite Ohms Zero Ohms |
| 15 (Yellow/Blue) |
Off |
Infinity In "N" |
| 15 (Yellow/Blue) |
Off |
Zero Ohms In Any Gear |
| 17 (Red) |
On |
10-12V |
| 19 (Green/Black) |
On |
10-12V |
| 20 (Green/Yellow) |
On |
.1V Or 4-5V |
| 21 (Black/White) |
On |
.1V Or 4-5V |
| 22 (Yellow/Green) |
Eng. On |
1-3V |
| 23 (White/Black) |
Off |
100-20,000 Ohms |
| 24 (Blue/Green)
Closed Throttle Open Throttle |
Off |
Zero Ohms Infinity |
| 27 (Black/White) |
On |
10-12V |
| 29 (White) |
On |
10-12V |
| 30 (Brown/Red) |
Off |
Zero Ohms |
| 33 (Lt. Green) |
Off |
Zero Ohms |
| 36 (White/Red) |
Off |
Over 250 Ohms |
| 41 (White) |
On |
10-12V |
| 42 (Brown/Red) |
Off |
Zero Ohms |
| 44 (Brown/Red) |
Off |
Zero Ohms |
| 45 (Green/Red) |
On |
0-1V |
| 48 (NCA) |
Eng. On |
0.1-1.0V |
| 49 (Red/Blue) |
On |
10-12V |
| 51 (Black) |
Off |
Zero Ohms |