Code 42: Idle Switch
NOTE:
Refer to illustration for ECU connector and terminal identification. See Figure
.
- Turn ignition on. Backprobing ECU connector F120, measure voltage between ground and terminal No. 16 (Green/Red wire) of ECU. With throttle closed, voltage should be less than one volt. With throttle fully open, voltage should be more than 8 volts. If voltage is not as specified, go to next step. If voltage is as specified, check for poor ECU connector contact. Repair connector and/or wiring harness as necessary. If connector and wiring harness are okay, replace ECU.
- Turn ignition off. Disconnect throttle switch connector. Measure resistance between terminal No. 2 and terminal No. 3 at throttle switch. See Fig 1
. With throttle closed, resistance should be less than one ohm. With throttle fully open, resistance should be infinite. If resistance is as specified, go to next step. If resistance is not as specified, check throttle switch adjustment. See ADJUSTMENTS
article. If throttle switch is adjusted properly, replace throttle switch.
Courtesy of SUBARU OF AMERICA, INC.
- Disconnect ECU connectors. Measure resistance between ECU and throttle switch connectors and between ECU connector and ground. See IDLE SWITCH RESISTANCE SPECIFICATIONS
table. If resistance is as specified, check for poor ECU connector contact. Repair connector and/or wiring harness as necessary. If connector and wiring harness are okay, replace ECU. If resistance is not as specified, repair connector and/or wiring harness as necessary.
IDLE SWITCH RESISTANCE SPECIFICATIONS
| Measure Between Terminals |
Ohms |
| No. 1
& No. 2 |
Less Than One |
| No. 1
& Ground |
Less Than 10 |
| No. 6
& Ground |
Infinite |
| No. 6
& No. 3 |
Less Than One |
| No. 10
& Ground |
Less Than 10 |
| No. 10
& No. 2 |
Less Than 10 |