DTC B2789: Id Code Box Communication

DTC detecting condition:

When communication between keyless access Control Module and ID code box is interrupted for a set amount of time.
Open or short circuit in the wiring harness between keyless access Control Module and ID code box

Trouble symptom:

Engine will not start.

CAUTION: For replacement procedure of keyless access Control Module and ID code box, refer to the "REGISTRATION MANUAL FOR IMMOBILIZER" provided as a separate volume.

Wiring diagram:

Push button start system Ref. to WIRING DIAGRAM , Push Button Start System.

Fig 1: ID Code Box Communication - Wiring Diagram

Courtesy of SUBARU OF AMERICA, INC.

Step	Check	Yes	No
1 CHECK DTC. Using the Subaru Select Monitor, clear the memory. Ref. to CLEAR MEMORY MODE . Read the DTC using the Subaru Select Monitor. Ref. to READ DIAGNOSTIC TROUBLE CODE (DTC) .	Is DTC B2789 displayed?	Go to step 2 .	Even if DTC is displayed, the circuit has returned to a normal condition at this time. Reproduce the failure, and then perform the diagnosis again. NOTE: In this case, temporary poor contact of connector, temporary open or short circuit of harness may be the cause.
2 CHECK HARNESS (OPEN CIRCUIT). Disconnect the keyless access Control Module connector. Disconnect the ID code box connector. Using the tester, measure the resistance between terminals. Connector & terminal (B574) No. 17 - (B422) No. 2:	Is the resistance less than 1 Ω?	Go to step 3 .	Repair or replace the open circuit of harness.
3 CHECK HARNESS (GROUND SHORT CIRCUIT). Using a tester, measure the resistance between the keyless access Control Module connector and chassis ground, and between ID code box connector and chassis ground. Connector & terminal (B574) No. 17 - Chassis ground:	Is the resistance 10 kΩ or more?	Go to step 4 .	Repair or replace the short circuit of the harness.
4 CHECK HARNESS (OPEN CIRCUIT). Using a tester, measure the resistance between ID code box connector and chassis ground. Connector & terminal (B422) No. 5 - Chassis ground:	Is the resistance less than 1 Ω?	Go to step 5 .	Repair or replace the open circuit of harness.
5 CHECK HARNESS. Using a tester, measure the voltage between ID code box connector and chassis ground. Connector & terminal (B422) No. 1 (+) - Chassis ground (-):	Is the voltage 11 - 14 V?	Go to step 6 .	Repair or replace the faulty portion of the power supply circuit.
6 CHECK ID CODE BOX. Using the Subaru Select Monitor, clear the memory. Ref. to CLEAR MEMORY MODE . Read the DTC using the Subaru Select Monitor. Ref. to READ DIAGNOSTIC TROUBLE CODE (DTC) .	Is DTC B2785 displayed?	Replace the keyless access Control Module. Ref. to Keyless Access Control Module .	Go to step 7 .
7 CHECK STEERING LOCK CONTROL MODULE. Turn the ignition switch to ON. Using the Subaru Select Monitor, clear the memory. Ref. to CLEAR MEMORY MODE . Read the DTC using the Subaru Select Monitor. Ref. to READ DIAGNOSTIC TROUBLE CODE (DTC) .	Is DTC B2789 displayed?	Replace the ID code box. Ref. to ID Code Box .	Even if DTC is displayed, the circuit has returned to a normal condition at this time. Reproduce the failure, and then perform the diagnosis again. NOTE: In this case, temporary poor contact of connector, temporary open or short circuit of harness may be the cause.