Impreza WRX 2.0L
- Turn ignition off. Remove main relay. Main relay is located under right side of dash. Using jumper wires, connect battery voltage to relay terminal No. 1 and ground terminal No. 2. Using a DVOM, measure resistance between terminals No. 3 and 5 and between terminals No. 4 and 6. See Figure . If resistance is less than 10 ohms at both test points, go to next step. If resistance is not less than 10 ohms at both test points, replace main relay.
- Turn ignition off. Disconnect connectors from Engine Control Module (ECM) located under right side of instrument panel behind glove compartment. Using a DVOM, measure resistance between specified terminals on harness side of specified ECM electrical harness connector and good chassis ground point. See ECM GROUND CIRCUIT RESISTANCE (IMPREZA WRX 2.0L)
table. See Fig 1
. If resistance is as specified, go to next step. If resistance is not as specified, repair open circuit in suspect ground circuit. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.ECM GROUND CIRCUIT RESISTANCE (IMPREZA WRX 2.0L)
ECM Connector & Terminal No. (Wire Color) Specification 17-Pin B84 - Manual Transaxle Only 1 (Black/Red) Less Than 5 Ohms 22-Pin B134 7 (Black/Red) Less Than 5 Ohms 15 (Black/Red) Less Than 5 Ohms 22 (Black/White) Less Than 5 Ohms 24-Pin B136 8 (Black/Yellow) Less Than 5 Ohms 17 (Black/White) Less Than 5 Ohms 18 (Black) Less Than 5 Ohms 31-Pin B137 8 (Black/Blue) Less Than 5 Ohms 9 (Black/Blue) Less Than 5 Ohms - With ignition off and all ECM connectors still disconnected, measure voltage between harness side of 22-pin ECM electrical harness connector B134 terminal No. 5 (Green/Red wire) and 31-pin ECM electrical harness connector B137 terminal No. 10 (Black/Red wire) and good chassis ground point. See Fig 1 . If voltage is greater than 10 volts at both test points, go to next step. If voltage is not greater than 10 volts at both test points, repair suspect power feed circuit. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
- Turn ignition off and leave all ECM connectors disconnected. Using a DVOM, measure resistance between harness side of 22-pin ECM electrical harness connector B134 terminal No. 6 (Light Green/White wire) and good chassis ground point. See Fig 1 . If resistance is greater than one megohm, go to next step. If resistance is not greater than one megohm, repair short to ground in harness between ECM and main relay, and check ECM for damage. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
- Turn ignition off and reconnect all ECM connectors. Turn ignition on. Backprobing, measure voltage between harness side of 22-pin ECM electrical harness connector B134 terminal No. 6 (Light Green/White wire) and good chassis ground point. See Fig 1 . If voltage is greater than 10 volts, go to next step. If voltage is not greater than 10 volts, replace ECM.
- Turn ignition off. Disconnect main relay Brown 6-pin electrical harness connector. Main relay is located under right side of dash. Turn ignition on. Using a DVOM, measure voltage between main relay Brown 6-pin electrical harness connector terminal No. 2 (Light Green/White wire) and good chassis ground point. See Figure . If voltage is greater than 10 volts, go to next step. If voltage is not greater than 10 volts, repair open circuit in Light Green/White wire between ECM and main relay. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
- With main relay Brown 6-pin electrical harness connector disconnected, turn ignition off. Using a DVOM, measure resistance between main relay Brown 6-pin electrical harness connector terminal No. 1 (Black wire) and good chassis ground point. See Figure . If resistance is less than 5 ohms, go to next step. If resistance is not less than 5 ohms, repair open circuit in ground circuit (Black wire) between main relay and chassis ground point located at right side of instrument panel. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
- With main relay Brown 6-pin electrical harness connector disconnected, measure voltage between main relay Brown 6-pin electrical harness connector terminals No. 5 (Blue/Red wire) and No. 6 (Black/Red wire) and good chassis ground point. See Figure . If voltage is greater than 10 volts at both test points, go to next step. If voltage is not greater than 10 volts at both test points, repair open or short to ground in suspect power feed circuit between main relay and main fuse block located in engine compartment. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
- Turn ignition off and reconnect main relay Brown 6-pin electrical harness connector. Turn ignition on. Backprobing, measure voltage on Yellow/Blue wires between 31-pin ECM electrical harness connector B137 terminals No. 2 and 3 and good chassis ground point. See Fig 1 . If voltage is greater than 10 volts at both test points, check ignition control system. See IGNITION CONTROL SYSTEM . If voltage is not greater than 10 volts at both test points, repair open or short to ground in suspect wire between ECM and main relay. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.