Subaru Legacy BN/BS (2015-2019) Service Manual: Dtc b27a8 trunk/rear gate external antenna open

Subaru Legacy BN/BS (2015-2019) Service Manual / Keyless access with push button start system (diagnostics) / Diagnostic procedure with diagnostic trouble code (dtc) / Dtc b27a8 trunk/rear gate external antenna open

DTC DETECTING CONDITION:

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

TROUBLE SYMPTOM:

Keyless access system does not function.

(Unable to unlock with the rear gate opener button, or unable to lock with the rear lock button, unable to open the trunk with the trunk opener button)

CAUTION:

For replacement procedure of keyless access CM, refer to the “REGISTRATION MANUAL FOR IMMOBILIZER” provided as a separate volume.

WIRING DIAGRAM:

NOTE:

For the coupling connector, refer to “WIRING SYSTEM”.

Keyless access with push button start system Keyless Access With Push Button Start System > WIRING DIAGRAM

• Sedan model

• OUTBACK model

STEP	CHECK	YES	NO
1.CHECK LAN SYSTEM. Inspect LAN system. Basic Diagnostic Procedure > PROCEDURE	Is LAN system normal-	Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC B27A8 TRUNK/REAR GATE EXTERNAL ANTENNA OPEN	Perform the inspection according to the diagnosis for LAN system.
2.CHECK CONNECTOR. 1) Disconnect the keyless access CM connector. 2) Disconnect the rear exterior antenna connector.	Is the connector OK-	Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC B27A8 TRUNK/REAR GATE EXTERNAL ANTENNA OPEN	Repair or replace the connector.
3.CHECK POWER SUPPLY CIRCUIT. Using a tester, measure the voltage between the keyless access CM connector and chassis ground. Connector & terminal (i75) No. 24 (+) — Chassis ground (−):	Is the voltage 9.5 — 16 V-	Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC B27A8 TRUNK/REAR GATE EXTERNAL ANTENNA OPEN	Check the power supply circuit.
4.CHECK HARNESS (OPEN CIRCUIT). Using a tester, measure the resistance between the keyless access CM connector and rear external antenna connector. Connector & terminal Sedan model (i241) No. 15 — (R299) No. 3: (i241) No. 16 — (R299) No. 1: OUTBACK model (i241) No. 15 — (D45) No. 3: (i241) No. 16 — (D45) No. 1:	Is the resistance less than 1 --	Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC B27A8 TRUNK/REAR GATE EXTERNAL ANTENNA OPEN	Repair or replace the open circuit of harness.
5.CHECK HARNESS (GROUND SHORT CIRCUIT). Using a tester, measure the resistance between the keyless access CM connector and chassis ground. Connector & terminal Sedan model (i241) No. 15 — Chassis ground: (i241) No. 16 — Chassis ground: OUTBACK model (i241) No. 15 — Chassis ground: (i241) No. 16 — Chassis ground:	Is the resistance 10 k- or more-	Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC B27A8 TRUNK/REAR GATE EXTERNAL ANTENNA OPEN	Repair or replace the short circuit of the harness.
6.CHECK DTC. 1) Connect the keyless access CM connector. 2) Using the Subaru Select Monitor, clear the memory. Clear Memory Mode 3) Read DTC using the Subaru Select Monitor. Read Diagnostic Trouble Code (DTC)	Is DTC B27A8 displayed-	Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC B27A8 TRUNK/REAR GATE EXTERNAL ANTENNA OPEN	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.
7.CHECK REAR EXTERIOR ANTENNA. 1) Replace the rear exterior antenna with the rear interior antenna. Keyless Access Indoor Antenna Keyless Access Outdoor Antenna 2) Using the Subaru Select Monitor, clear the memory. Clear Memory Mode 3) Read DTC using the Subaru Select Monitor. Read Diagnostic Trouble Code (DTC)	Is DTC B27A8 displayed-	Replace the keyless access CM. Keyless Access CM	Malfunction occurred in the rear external antenna.

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