Subaru Crosstrek Service Manual: Dtc b2789 id code box communication

DTC detecting condition:

• When communication between keyless access CM and ID code box is interrupted for a set amount of time.

• Open or short circuit in the wiring harness between keyless access CM and ID code box

For replacement procedure of keyless access CM and ID code box, refer to the “REGISTRATION MANUAL FOR IMMOBILIZER” provided as a separate volume.

1.CHECK DTC.

1) Using the Subaru Select Monitor, clear the memory. Clear Memory Mode">

2) Read the DTC using the Subaru Select Monitor. Read Diagnostic Trouble Code (DTC)">

Is DTC B2789 displayed?

Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC B2789 ID CODE BOX COMMUNICATION">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).

1) Disconnect the keyless access CM connector.

2) Disconnect the ID code box connector.

3) Using the tester, measure the resistance between terminals.

Connector & terminal

(B574) No. 17 — (B422) No. 2:

Is the resistance less than 1 ??

Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC B2789 ID CODE BOX COMMUNICATION">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 CM connector and chassis ground, and between ID code box connector and chassis ground.

Connector & terminal

(B574) No. 17 — Chassis ground:

Is the resistance 10 k? or more?

Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC B2789 ID CODE BOX COMMUNICATION">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 ??

Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC B2789 ID CODE BOX COMMUNICATION">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?

Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC B2789 ID CODE BOX COMMUNICATION">Go to Step 6.

Repair or replace the faulty portion of the power supply circuit.

6.CHECK ID CODE BOX.

1) Using the Subaru Select Monitor, clear the memory. Clear Memory Mode">

2) Read the DTC using the Subaru Select Monitor. Read Diagnostic Trouble Code (DTC)">

Is DTC B2785 displayed?

Replace the keyless access CM. Keyless Access CM">

Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC B2789 ID CODE BOX COMMUNICATION">Go to Step 7.

7.CHECK STEERING LOCK CM.

1) Turn the ignition switch to ON.

2) Using the Subaru Select Monitor, clear the memory. Clear Memory Mode">

3) Read the DTC using the Subaru Select Monitor. Read Diagnostic Trouble Code (DTC)">

Is DTC B2789 displayed?

Replace the ID code box. 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.

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