D: DTC P1572 IMM Circuit Failure (Except Antenna Circuit)

DTC DETECTING CONDITION:

Communication failure between body integrated unit and ECM

WIRING DIAGRAM:

Fig 1: IMM Circuit Failure (Except Antenna Circuit) - Wiring Diagram

G05023163

DIAGNOSTIC 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 more than 10 V?	Go to step 2.	Check the harness for open or short circuits 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 more than 10 V?	Go to step 3.	Check the harness for open or short circuit between 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, 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 HARNESS BETWEEN BODY INTEGRATED UNIT AND ECM. Disconnect the harness connector from body integrated unit and ECM. Measure the resistance between body integrated unit harness connector terminal and ECM harness connector terminal. Connector & terminal Turbo model (B280) No. 18 - (B137) No. 19: Excluding turbo models (B280) No. 18 - (B136) No. 26:	Is resistance less than 10 Ω?	Go to step 5.	Repair the open circuit of harness between body integrated unit and ECM.
5 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 Turbo model (B280) No. 28 - (B137) No. 27: Excluding turbo models (B280) No. 28 - (B136) No. 34:	Is resistance less than 10 Ω?	Go to step 6.	Repair the open circuit of harness between body integrated unit and ECM.
6 CHECK HARNESS OF COMMUNICATION LINE. 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, No. 28 (+) - Chassis ground (-):	Is the voltage 0 V?	Go to step 7.	Repair the harness between body integrated unit and ECM, because there is short circuit with battery voltage line or ignition switch "ON" line.
7 CHECK HARNESS OF COMMUNICATION LINE. Measure voltage between the ECM harness connector terminal and engine ground. Connector & terminal Turbo model (B137) No. 19, No. 27 (+) - Engine ground (-): Excluding turbo models (B136) No. 26, No. 34 (+) - Engine ground (-):	Is the voltage 0 V?	Go to step 8.	Repair the harness between body integrated unit and ECM, because there is short circuit with battery voltage line or ignition switch "ON" line.
8 CHECK ECM BY COMMUNICATION LINE CHECK. Connect the harness connector to ECM. Disconnect the harness connector from body integrated unit. Start the communication line check. < Ref. to COMMUNICATION LINE CHECK , OPERATION, Subaru Select Monitor. >	Does "Communication Line not Shorted" appear on the screen?	Replace the body integrated unit < Ref. to , BODY INTEGRATED UNIT . > and replace all the ignition keys (including transponder). Execute the registration procedure next. Refer to the "Registration Manual For Immobilizer".	Replace the ECM. < Ref. to ENGINE CONTROL MODULE (ECM) . > < Ref. to ENGINE CONTROL MODULE (ECM) . > Perform the registration procedure next. Refer to the "Registration Manual For Immobilizer".