DTC B27A5: Front Internal Antenna Open

DTC detecting condition:

When open circuit occurs in the harness between keyless access control module and front interior antenna.

Trouble symptom:

The keyless access with push button start system does not operate. (When the access key is in the front area of the passenger room)

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.

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 .

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.
CHECK CONNECTOR .
1. Disconnect the keyless access control module connector.
2. Disconnect the front interior antenna connector.
3. Check the connector.
Is the check result OK?

Yes : Go to 3.

No : Repair or replace the connector.
CHECK POWER SUPPLY CIRCUIT .
Using a tester, measure the voltage between the keyless access control module connector and chassis ground.

Connector & terminal

(i75) 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) .
Using a tester, measure the resistance between the keyless access control module connector and front interior antenna connector, and between keyless access control module connector and chassis ground.

Connector & terminal

(i241) No. 25 - (i71) No. 1:

(i241) No. 12 - (i71) No. 3:

(i241) No. 17 - Chassis ground:

(i75) 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

(i241) No. 25 - Chassis ground:

(i241) No. 12 - 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 keyless access control module connector.
2. Using the Subaru Select Monitor, perform the clear memory of [Keyless Access with Push Button Start]. Ref. to COMMON (diag)>CLEAR MEMORY .
3. Read the DTC of [Keyless Access with Push Button Start] using the Subaru Select Monitor. Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>Diagnostic Trouble Code (DTC) .
Is DTC B27A5 displayed?

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 again.

NOTE: In this case, temporary poor contact of connector, temporary open or short circuit of harness may be the cause.
CHECK FRONT INTERIOR ANTENNA .
1. Replace the rear interior antenna with the front interior antenna. Ref. to SECURITY AND LOCKS>KEYLESS ACCESS INDOOR ANTENNA .
2. Using the Subaru Select Monitor, perform the clear memory of [Keyless Access with Push Button Start]. Ref. to COMMON (diag)>CLEAR MEMORY .
3. Read the DTC of [Keyless Access with Push Button Start] using the Subaru Select Monitor. Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>Diagnostic Trouble Code (DTC) .
Is DTC B27A5 displayed?

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

No : Malfunction occurred in the front interior antenna.