DTC B2786: Steering Lock Control Module Communication

DTC detecting condition: 

When the LIN transmission frame cannot be received for 10 consecutive seconds during the LIN bus Wake UP after being received once from the steering lock control module.

Trouble symptom: 

The steering lock cannot be released.

Wiring diagram: 

Push button start system. Refer to WIRING SYSTEM>PUSH BUTTON START SYSTEM>WIRING DIAGRAM .

• Engine type: FA

  Courtesy of SUBARU OF AMERICA, INC.

• Engine type: EJ

  Courtesy of SUBARU OF AMERICA, INC.

1. CHECK DTC. 

   Read DTCs of «Keyless Access with Push Button Start» using the Subaru Select Monitor. Refer to KEYLESS ACCESS WITH PUSH BUTTON START SYSTEM (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

   Is a DTC other than DTC B2786 displayed? (Current malfunction)

   Yes:  Perform the diagnosis of DTCs other than B2786.

   No:  Go to  2.

2. CHECK HARNESS (OPEN CIRCUIT). 
   1. Disconnect the keyless access control module connector.
   2. Disconnect the steering lock control module connector.
   3. Using the tester, measure the resistance between terminals.

      Connector & terminal 

      (B574) No. 20 - (B424) 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 

   (B574) 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 

   (B424) 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 

      (B424) No. 6 (+) - Chassis ground (-):

      (B424) 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. Turn the ignition switch to ON.
   2. Perform the clear memory for «Keyless Access with Push Button Start» using the Subaru Select Monitor. Refer to KEYLESS ACCESS WITH PUSH BUTTON START SYSTEM (DIAGNOSTICS)>CLEAR MEMORY .
   3. Read DTCs of «Keyless Access with Push Button Start» using the Subaru Select Monitor. Refer to KEYLESS ACCESS WITH PUSH BUTTON START SYSTEM (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

      Is DTC B2785 displayed? (Current malfunction)

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

      No:  Go to  7.

7. CHECK STEERING LOCK control module. 
   1. Turn the ignition switch to ON.
   2. Perform the clear memory for «Keyless Access with Push Button Start» using the Subaru Select Monitor. Refer to KEYLESS ACCESS WITH PUSH BUTTON START SYSTEM (DIAGNOSTICS)>CLEAR MEMORY .
   3. Read DTCs of «Keyless Access with Push Button Start» using the Subaru Select Monitor. Refer to KEYLESS ACCESS WITH PUSH BUTTON START SYSTEM (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

   Is DTC B2786 displayed? (Current malfunction)

   Yes:  Replace the steering lock control module. Refer 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.