DTC B2786: Steering Lock Control Module Communication

DTC detecting condition: 

When LIN transmission frame is received from steering lock Control Module once, but cannot be received for 10 seconds in a row during LIN bus Wake-up.

Trouble symptom: 

The steering lock cannot be released.

Wiring diagram: 

Keyless access with push button start system Ref. to WIRING SYSTEM>KEYLESS ACCESS WITH PUSH BUTTON START SYSTEM>WIRING DIAGRAM .

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK DTC  .
   1. Turn the ignition switch to ON.
   2. Read the DTC of [Keyless Access with Push Button Start (Collation)] using the Subaru Select Monitor. Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

   Is any DTC other than DTC B2786 displayed? (Current code)

   Yes:  Perform the diagnosis of DTCs other than B2786. Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC)>LIST .

   No:  Go to  2.

2. CHECK HARNESS (OPEN CIRCUIT)  .
   1. Turn the ignition switch to OFF.
   2. Disconnect the keyless access Control Module connector.
   3. Disconnect the steering lock Control Module connector.
   4. Using the tester, measure the resistance between terminals.

      Connector & terminal 

      (i241) No. 20 - (i47) No. 5:

   Is the resistance less than 1 Ω?

   Yes:  Go to  3.

   No:  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 and chassis ground.

   Connector & terminal 

   (i241) No. 20 - Chassis ground:

   Is the resistance 10 kΩ or more?

   Yes:  Go to  4.

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

4. CHECK HARNESS (OPEN CIRCUIT)  .

   Using a tester, measure the resistance between the steering lock Control Module connector and chassis ground.

   Connector & terminal 

   (i47) No. 1 - 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 the steering lock Control Module connector and chassis ground.

      Connector & terminal 

      (i47) No. 6 (+) - Chassis ground (-):

      (i47) No. 7 (+) - 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 (Collation)]. Ref. to COMMON (DIAGNOSTICS)>CLEAR MEMORY .
   2. Read the DTC of [Keyless Access with Push Button Start (Collation)] using the Subaru Select Monitor. Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

   Is DTC B2785 displayed?

   Yes:  Replace the keyless access Control Module. Ref. to SECURITY AND LOCKS>KEYLESS ACCESS Control Module .

   No:  Go to  7.

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

   Is DTC B2786 displayed? (Current code)

   Yes:  Replace the steering lock Control Module. Ref. to SECURITY AND LOCKS>STEERING LOCK 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.