LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Subaru >> 2017 >> WRX Base >> Repair and Diagnosis (Single Page) >> Accessories & Equipment >> Anti-Theft Systems >> Security And Locks - Keyless Access (W/ Push Button Start) (Diagnostics) >> Diagnostic Procedure with Diagnostic Trouble Code (DTC) >> DTC B27A7 Trunk/Rear Gate Internal Antenna Open
April 5, 2026: LEMON Manuals is launched! Read the announcement.

DTC B27A7 Trunk/Rear Gate Internal Antenna Open

DTC DETECTING CONDITION: 

When open circuit occurs in the harness between Keyless Access Control Module 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 Control Module, refer to the "REGISTRATION MANUAL FOR IMMOBILIZER" provided as a separate volume.

WIRING DIAGRAM: 

Keyless access system <Ref. to WIRING DIAGRAM , Keyless Access System.>

Fig 1: Trunk/Rear Gate Internal Antenna Open - Wiring Diagram
G10271485Courtesy of SUBARU OF AMERICA, INC.
Step Check Yes No
1 CHECK LAN SYSTEM. 
Inspect LAN system. <Ref. to PROCEDURE , Basic Diagnostic Procedure.>
Is the check result OK? Go to step . Perform the inspection according to the diagnosis for LAN system.
2 CHECK CONNECTOR. 
  1. Disconnect the Keyless Access Control Module connector.
  2. Disconnect the rear interior antenna connector.
  3. Check the connector.
Is the check result OK? Go to step . Repair or replace the connector.
3 CHECK HARNESS (OPEN CIRCUIT). 
Using a tester, measure the resistance between the Keyless Access Control Module connector and rear interior antenna connector, and between Keyless Access Control Module connector and chassis ground.
Connector & terminal 
(B573) No. 8 - (R297) No. 3: 
(B573) No. 9 - (R297) No. 1: 
(B572) No. 11 - Chassis ground: 
Is the resistance less than 1 Ω? Go to step . 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 
(B573) No. 8 - Chassis ground: 
(B573) No. 9 - Chassis ground: 
Is the resistance 10 kΩ or more? Go to step . 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 CLEAR MEMORY MODE .>
  3. Read the DTC using Subaru Select Monitor. <Ref. to READ DIAGNOSTIC TROUBLE CODE (DTC) .>
Is DTC B27A7 displayed? Go to step . 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 REAR INTERIOR ANTENNA. 
  1. Replace the rear interior antenna with the front interior antenna. <Ref. to Keyless Access Indoor Antenna .>
  2. Using the Subaru Select Monitor, clear the memory. <Ref. to CLEAR MEMORY MODE .>
  3. Read the DTC using Subaru Select Monitor. <Ref. to READ DIAGNOSTIC TROUBLE CODE (DTC) .>
Is DTC B27A7 displayed? Replace the Keyless Access Control Module. <Ref. to Keyless Access Control Module .> Malfunction occurred in the rear interior antenna.