DTC P1572 IMM Circuit Failure (Except Antenna Circuit): Wiring Diagram

Fig 1: Body Integrated Unit And ECM - Wiring Diagram

Courtesy of SUBARU OF AMERICA, INC.

DIAGNOSIS PROCEDURE CHART

Step	Check	Yes	No
1 CHECK BODY INTEGRATED UNIT POWER SUPPLY CIRCUIT. Turn the ignition switch to OFF. Disconnect the harness connector from body integrated unit. Measure the voltage between body integrated unit harness connector terminal and chassis ground. Connector & terminal (B280) No. 7 (+) - Chassis ground (-): (B281) No. 2 (+) - Chassis ground (-):	Is the voltage 10 V or more?	Go to step 2 .	Check the harness for open or short circuit between the body integrated unit and fuse.
2 CHECK BODY INTEGRATED UNIT POWER SUPPLY CIRCUIT. Turn the ignition switch to ON. (engine OFF) Measure the voltage between body integrated unit harness connector terminal and chassis ground. Connector & terminal (i84) No. 1 (+) - Chassis ground (-):	Is the voltage 10 V or more?	Go to step 3 .	Check the harness for open or short circuit between the body integrated unit and ignition switch.
3 CHECK BODY INTEGRATED UNIT GROUND CIRCUIT. Turn the ignition switch to OFF. Measure the resistance between body integrated unit harness connector terminal and chassis ground. Connector & terminal (B280) No. 22 - Chassis ground: (B281) No. 8 - Chassis ground: (B281) No. 9 - Chassis ground:	Is the resistance less than 10 Ω?	Go to step 4 .	Repair the open circuit of body integrated unit ground circuit.
4 CHECK GROUND CIRCUIT FOR ECM. Measure the resistance between the ECM ground terminal and engine ground.	Is the resistance less than 10 Ω	Go to step 5 .	Repair ground circuit of ECM.
5 CHECK HARNESS BETWEEN BODY INTEGRATED UNIT AND ECM. Disconnect the harness connector from the ECM and body integrated unit. Measure the resistance between body integrated unit harness connector terminal and ECM harness connector terminal. Connector & terminal (B280) No. 18 - (B136) No. 26:	Is the resistance less than 10 Ω?	Go to step 6 .	Repair the open circuit of the harness between the body integrated unit and ECM.
6 CHECK HARNESS BETWEEN BODY INTEGRATED UNIT AND ECM. Measure the resistance between body integrated unit harness connector terminal and ECM harness connector terminal. Connector & terminal (B280) No. 28 - (B136) No. 34:	Is the resistance less than 10 Ω?	Go to step 7 .	Repair the open circuit of the harness between the body integrated unit and ECM.
7 CHECK COMMUNICATION CIRCUIT HARNESS. Turn the ignition switch to ON. (engine OFF) Measure the voltage between body integrated unit harness connector terminal and chassis ground. Connector & terminal (B280) No. 18 (+) - Chassis ground (-): (B280) No. 28 (+) - Chassis ground (-):	Is the voltage 0 V?	Go to step 8 .	Because the battery voltage or ignition switch "ON" circuit is shorted, repair the harness between the body integrated unit and ECM.
8 CHECK COMMUNICATION CIRCUIT HARNESS. Measure voltage between the ECM harness connector terminal and engine ground. Connector & terminal (B136) No. 26 (+) - Engine ground (-): (B136) No. 34 (+) - Engine ground (-):	Is the voltage 0 V?	Go to step 9 .	Because the battery voltage or ignition switch "ON" circuit is shorted, repair the harness between the body integrated unit and ECM.
9 CHECK ECM BY COMMUNICATION LINE CHECK. Connect the harness connector to ECM. Disconnect the harness connector from body integrated unit. Start the communication line short check. Ref. to COMMUNICATION LINE CHECK , OPERATION, Subaru Select Monitor.	Is the communication line check OK?	Replace the body integrated unit Ref. to BODY INTEGRATED UNIT . Replace all ignition keys (including the transponder). Execute the registration procedure next. Refer to the "PC application help for Subaru Select Monitor".	Replace the ECM. Ref. to ENGINE CONTROL MODULE (ECM) . Ref. to ENGINE CONTROL MODULE (ECM) . Perform the registration procedure next. Refer to the "PC application help for Subaru Select Monitor".