DTC B27A8: Trunk/Rear Gate External Antenna Open

DTC detecting condition:

When open circuit occurs in the harness between keyless access Control Module and rear exterior antenna.

Trouble symptom:

Keyless access system does not function.

(Cannot unlock using the trunk opener button.)

CAUTION:

For replacement procedure of keyless access Control Module, refer to the "REGISTRATION MANUAL FOR IMMOBILIZER" provided as a separate volume.
Before performing diagnosis, refer to "CAUTION" in "General Description". Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>GENERAL DESCRIPTION>CAUTION .

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.

CHECK LAN SYSTEM .
Perform the diagnosis for 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.
CHECK CONNECTOR .
1. Turn the ignition switch to OFF.
2. Disconnect the connector from the keyless access Control Module.
3. Disconnect the connector from the rear exterior antenna.
4. Check the connector.
Is the check result OK?

Yes: Go to 3.

No: Repair or replace the connector.
CHECK POWER SUPPLY CIRCUIT .
1. Turn the ignition switch to ON.
2. Using a tester, measure the voltage between the keyless access Control Module connector and chassis ground.
  Connector & terminal
  
  (i91) No. 4 (+) - Chassis ground (-):
Is the voltage 9.5 - 16 V?

Yes: Go to 4.

No: Check the power supply circuit.
CHECK HARNESS (OPEN CIRCUIT) .
1. Turn the ignition switch to OFF.
2. Using a tester, measure the resistance between the keyless access Control Module connector and rear exterior antenna connector, and between keyless access Control Module connector and chassis ground.
  Connector & terminal
  
  (i92) No. 8 - (L106) No. 1:
  
  (i92) No. 7 - (L106) No. 2:
  
  (i92) No. 17 - Chassis ground:
  
  (i91) No. 20 - Chassis ground:
Is the resistance less than 1 Ω?

Yes: Go to 5.

No: Repair or replace the open circuit of harness.
CHECK HARNESS (GROUND SHORT CIRCUIT) .
Using a tester, measure the resistance between the keyless access Control Module connector and chassis ground.

Connector & terminal

(i92) No. 8 - Chassis ground:

(i92) No. 7 - Chassis ground:

Is the resistance 10 kΩ or more?

Yes: Go to 6.

No: Repair or replace the short circuit of the harness.
CHECK DTC .
1. Connect the disconnected connectors.
2. Turn the ignition switch to ON.
3. Using the Subaru Select Monitor, perform the clear memory of [Keyless Access with Push Button Start (Collation)]. Ref. to COMMON (DIAGNOSTICS)>CLEAR MEMORY .
4. 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 B27A8 displayed? (Current code)

Yes: Go to 7.

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.

NOTE: In this case, temporary poor contact of connector, temporary open or short circuit of harness may be the cause.
CHECK KEYLESS ACCESS CONTROL MODULE .
1. Turn the ignition switch to OFF.
2. Short the terminals of the rear exterior antenna connector (L106).
  Connector & terminal
  
  (L106) No. 1 - (L106) No. 2:
3. Turn the ignition switch to ON.
4. Using the Subaru Select Monitor, perform the clear memory of [Keyless Access with Push Button Start (Collation)]. Ref. to COMMON (DIAGNOSTICS)>CLEAR MEMORY .
5. 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 B27A8 displayed? (Current code)

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

No: Malfunction occurred in the rear external antenna.