DTC B2789: Id Code Box Communication

DTC detecting condition: 

When LIN transmission frame is received from ID code BOX once, but cannot be received for 10 seconds in a row during LIN bus Wake-up.

Trouble symptom: 

Engine will not start.

Wiring diagram: 

Immobilizer system Ref. to WIRING SYSTEM>IMMOBILIZER SYSTEM>WIRING DIAGRAM .

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK DTC  .
   1. Turn the ignition switch to ON.
   2. Using the Subaru Select Monitor, perform the clear memory of [Keyless Access with Push Button Start]. Ref. to COMMON (DIAG)>CLEAR MEMORY .
   3. Read the DTC of [Keyless Access with Push Button Start] using the Subaru Select Monitor. Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

   Is DTC B2789 displayed? (Current malfunction)

   Yes  : Go to  2 .

   No  : 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 (GROUND SHORT CIRCUIT)  .
   1. Turn the ignition switch to OFF.
   2. Disconnect the keyless access control module connector.
   3. Using a tester, measure the resistance between the keyless access control module connector and chassis ground.

      Connector and terminal 

      (i241) No. 20 - Chassis ground:

   Is the resistance 10 kΩ or more?

   Yes  : Go to  3 .

   No  : Repair or replace the short circuit of the harness.

3. CHECK HARNESS (OPEN CIRCUIT)  .
   1. Disconnect the ID code box connector.
   2. Using a tester, measure the resistance between the keyless access control module connector and the ID code box connector.

      Connector and terminal 

      (i241) No. 20 - (i33) No. 2:

   Is the resistance less than 1 Ω?

   Yes  : Go to  4 .

   No  : Repair or replace the open circuit of harness.

4. CHECK HARNESS (OPEN CIRCUIT)  .

   Using a tester, measure the resistance between ID code box connector and chassis ground.

   Connector and terminal 

   (i33) No. 5 - Chassis ground:

   Is the resistance less than 1 Ω?

   Yes  : Go to  5 .

   No  : Repair or replace the open circuit of harness.

5. CHECK HARNESS  .
   1. Turn the ignition switch to ON.
   2. Using a tester, measure the voltage between ID code box connector and chassis ground.

      Connector and terminal 

      (i33) No. 1 (+) - Chassis ground (-):

   Is the voltage 11 - 14 V?

   Yes  : Go to  6 .

   No  : Repair or replace the faulty portion of the power supply circuit.

6. CHECK STEERING LOCK CONTROL MODULE  .
   1. Using the Subaru Select Monitor, perform the clear memory of [Keyless Access with Push Button Start]. Ref. to COMMON (DIAG)>CLEAR MEMORY .
   2. Read the DTC of [Keyless Access with Push Button Start] using the Subaru Select Monitor. Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

   Is DTC B2789 displayed? (Current malfunction)

   Yes  : Replace the ID code box. Ref. to SECURITY AND LOCKS>ID CODE BOX .

   No  : Go to  7 .

7. CHECK ID CODE BOX  .
   1. Using the Subaru Select Monitor, perform the clear memory of [Keyless Access with Push Button Start]. Ref. to COMMON (DIAG)>CLEAR MEMORY .
   2. Read the DTC of [Keyless Access with Push Button Start] using the Subaru Select Monitor. Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

   Is DTC B2785 displayed? (Current malfunction)

   Yes  : Replace the keyless access control module. Ref. to SECURITY AND LOCKS>KEYLESS ACCESS CONTROL MODULE .

   No  : 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.