DTC B2785: Lin Communication

DTC detecting condition:

When the keyless access CONTROL MODULE detected the collation system LIN bus communication error three times in a row.

Trouble symptom:

The keyless access function may not be operable.

CAUTION: For replacement procedure of keyless access CONTROL MODULE and steering lock CONTROL MODULE, refer to the "REGISTRATION MANUAL FOR IMMOBILIZER" provided as a separate volume. Contact an Authorized Subaru Dealership.

Wiring diagram:

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

Courtesy of SUBARU OF AMERICA, INC.

CHECK DTC .
1. Using the Subaru Select Monitor, clear the memory. Ref. to KEYLESS ACCESS WITH PUSH BUTTON START SYSTEM (DIAGNOSTICS)>Clear Memory Mode
2. Read the DTC using Subaru Select Monitor. Ref. to KEYLESS ACCESS WITH PUSH BUTTON START SYSTEM (DIAGNOSTICS)>Read Diagnostic Trouble Code (DTC)
Is DTC B2785 displayed?

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.
CHECK HARNESS .
1. Disconnect the keyless access CONTROL MODULE connector.
2. Disconnect the steering lock CONTROL MODULE connector.
3. Disconnect the ID code box connector. (With ID code box)
4. Using the tester, measure the resistance between terminals.
  Connector & terminal
  
  (B574) No. 17 - (B424) No. 5:
  
  (B574) No. 17 - (B422) No. 2: (with ID code box)
Is the resistance less than 1 Ω?

Yes: Go to 3

No: Repair or replace the open circuit of harness.
CHECK HARNESS (GROUND SHORT CIRCUIT) .
Using the tester, measure the resistance between terminals.

Connector & terminal

(B424) No. 5 - Chassis ground:

(B574) No. 17 - Chassis ground:

(B422) No. 2 - Chassis ground: (with ID code box)

Is the resistance 10 kΩ or more?

Yes: Go to 4

No: Repair or replace the short circuit of the harness.
CHECK HARNESS .
1. Connect the keyless access CONTROL MODULE connector only.
2. Read the DTC using Subaru Select Monitor. Ref. to KEYLESS ACCESS WITH PUSH BUTTON START SYSTEM (DIAGNOSTICS)>Read 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 5
CHECK ID CODE BOX .
NOTE: For model without ID code box, go to the next step.
1. Connect only the ID code box.
2. Read the DTC using Subaru Select Monitor. Ref. to KEYLESS ACCESS WITH PUSH BUTTON START SYSTEM (DIAGNOSTICS)>Read Diagnostic Trouble Code (DTC)
Is DTC B2785 displayed?

Yes: Replace the ID code box. Ref. to SECURITY AND LOCKS>ID Code Box

No: Go to 6
CHECK STEERING LOCK CONTROL MODULE .
1. Replace the steering lock CONTROL MODULE, and then connect it. Ref. to SECURITY AND LOCKS>Steering Lock CONTROL MODULE
2. Using the Subaru Select Monitor, clear the memory. Ref. to KEYLESS ACCESS WITH PUSH BUTTON START SYSTEM (DIAGNOSTICS)>Clear Memory Mode
3. Read the DTC using Subaru Select Monitor. Ref. to KEYLESS ACCESS WITH PUSH BUTTON START SYSTEM (DIAGNOSTICS)>Read Diagnostic Trouble Code (DTC)
Is DTC B2785 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.