Subaru Legacy BN/BS (2015-2019) Service Manual: Dtc b27a7 trunk/rear gate internal 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 b27a7 trunk/rear gate internal antenna open

DTC DETECTING CONDITION:

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

TROUBLE SYMPTOM:

Keyless access system does not function. (when the access key is in the rear area of the passenger room (in the luggage room or trunk))

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

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 B27A7 TRUNK/REAR GATE INTERNAL 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 interior antenna connector.	Is the connector OK-	Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC B27A7 TRUNK/REAR GATE INTERNAL 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 B27A7 TRUNK/REAR GATE INTERNAL 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 interior antenna connector, and between rear interior antenna connector, keyless access CM connector and chassis ground. Connector & terminal (i241) No. 17 — (R297) No. 3: (i241) No. 18 — (R297) No. 1: (i75) No. 1 — Chassis ground: (i241) No. 21 — Chassis ground:	Is the resistance less than 1 --	Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC B27A7 TRUNK/REAR GATE INTERNAL 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 (i241) No. 17 — Chassis ground: (i241) No. 18 — Chassis ground:	Is the resistance 10 k- or more-	Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC B27A7 TRUNK/REAR GATE INTERNAL 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 B27A7 displayed-	Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC B27A7 TRUNK/REAR GATE INTERNAL 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 INTERIOR ANTENNA. 1) Replace the rear interior antenna with the front interior antenna. Keyless Access Indoor 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 B27A7 displayed-	Replace the keyless access CM. Keyless Access CM	Malfunction occurred in the rear interior antenna.

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