DTC B2786: Steering Lock Control Module Communication

DTC detecting condition: 

When communication between keyless access Control Module and steering lock Control Module is interrupted for a set amount of time.

Trouble symptom: 

The steering lock cannot be released.

Wiring diagram: 

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

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK DTC  .

   Read the DTC using the Subaru Select Monitor. Ref. to KEYLESS ACCESS WITH PUSH BUTTON START(DIAGNOSTICS)>Diagnostic Trouble Code (DTC) .

   Are DTCs other than DTC B2786 displayed?

   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 a tester, measure the resistance between the keyless access Control Module connector and steering lock Control Module connector.

      Connector & terminal

      (B574) No. 17 - (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 connector and chassis ground.

   Connector & terminal

   (B574) No. 17 - 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. Using the Subaru Select Monitor, clear the memory. Ref. to KEYLESS ACCESS WITH PUSH BUTTON START(DIAGNOSTICS)>Clear Memory .
   3. Read the DTC 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. Turn the ignition switch to ON.
   2. Using the Subaru Select Monitor, clear the memory. Ref. to KEYLESS ACCESS WITH PUSH BUTTON START(DIAGNOSTICS)>Clear memory .
   3. Read the DTC using Subaru Select Monitor. Ref. to KEYLESS ACCESS WITH PUSH BUTTON START(DIAGNOSTICS)>Diagnostic Trouble Code (DTC) .

   Is DTC B2786 displayed?

   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.