DTC B27A1: Driver Side External Antenna Open

DTC detecting condition: 

When open circuit occurs in the harness between keyless access CONTROL MODULE and driver's side front door outer handle.

Trouble symptom: 

Keyless access system does not function.

Wiring diagram: 

Keyless access system Ref. to WIRING SYSTEM>Keyless Access System>WIRING DIAGRAM

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK LAN SYSTEM  .

   Inspect LAN system. Ref. to LAN SYSTEM (DIAGNOSTICS)>Basic Diagnostic Procedure>PROCEDURE

   Is the check result OK?

   Yes: Go to  2

   No: Perform the inspection according to the diagnosis for LAN system.

2. CHECK CONNECTOR  .
   1. Disconnect the keyless access CONTROL MODULE connector.
   2. Disconnect the front door outer handle connector.
   3. Check the connector.

   Is the check result OK?

   Yes: Go to  3

   No: Repair or replace the connector.

3. CHECK HARNESS (OPEN CIRCUIT)  .

   Using a tester, measure the resistance between the keyless access CONTROL MODULE connector and front door outer handle connector, and between front door outer handle connector, keyless access CONTROL MODULE connector and chassis ground.

   Connector & terminal 

   (B574) No. 12 - (D66) No. 6:

   (B574) No. 13 - (D66) No. 3:

   (D66) No. 2 - Chassis ground:

   (B572) No. 11 - Chassis ground:

   Is the resistance less than 1 Ω?

   Yes: Go to  4

   No: Repair or replace the open circuit of harness.

4. 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. 12 - Chassis ground:

   (B574) No. 13 - Chassis ground:

   Is the resistance 10 kΩ or more?

   Yes: Go to  5

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

5. CHECK DTC  .
   1. Connect the keyless access CONTROL MODULE connector.
   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 B27A1 displayed?

   Yes: Go to  6

   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.
6. CHECK FRONT DOOR OUTER HANDLE  .
   1. Replace the driver's side front door outer handle with the passenger's front door outer handle. Ref. to SECURITY AND LOCKS>Front Outer Handle
   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 B27A1 displayed?

   Yes: Replace the keyless access CONTROL MODULE. Ref. to SECURITY AND LOCKS>Keyless Access CONTROL MODULE

   No: Replace the driver's side front door outer handle. Ref. to SECURITY AND LOCKS>Front Outer Handle