Cannot Lock When Using The Rear Lock Button

Trouble causes:

Malfunction of harness between keyless access control module and rear lock button
Rear lock button malfunction
Malfunction of harness between keyless access control module and exterior rear antenna
Keyless access control module malfunction
Exterior rear antenna malfunction
Malfunction of harness between the body integrated unit and rear gate lock actuator
Body integrated unit malfunction
Rear gate lock actuator malfunction

CAUTION:

Check that there are no other registered access keys inside the vehicle.
Check that the keyless access function is not stopped.
Inspect LAN system or keyless access with push button start system according to the basic diagnostic procedure, and make sure that DTC is not input.
When the keyless access control module is replaced, registration of the immobilizer is required. For the relevant procedures, 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 REAR GATE ACTUATOR .
While carrying the access key, operate the touch sensor (lock) and touch sensor (unlock).

When the switch is operated, does the rear gate lock/unlock?

Yes : Go to 2.

No : Go to 11.
CHECK REAR LOCK BUTTON .
1. Using the Subaru Select Monitor, check the following items in the [Data Monitor] of [Keyless Access with Push Button Start]. Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>DATA MONITOR .
  - [Rear Gate Request SW]
Does the data change between ON/OFF?

Yes : Go to 8.

No : Go to 3.
CHECK HARNESS (OPEN CIRCUIT) .
1. Disconnect the rear lock button connector and the keyless access control module connector.
2. Using a tester, measure the resistance between harness.
  Connector & terminal
  
  (D77) No. 3 - (i75) No. 17:
Is the resistance less than 10 Ω?

Yes : Go to 4.

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

Connector & terminal

(D77) No. 3 - Chassis ground:

Is the resistance 10 MΩ or more?

Yes : Go to 5.

No : Repair or replace the short of harness.
CHECK HARNESS (OPEN CIRCUIT) .
Using a tester, measure the resistance between harness and chassis ground.

Is the resistance less than 10 Ω?

Yes : Go to 6.

No : Repair or replace the open circuit of the harness.
CHECK REAR LOCK BUTTON (UNIT INSPECTION) .
Measure the resistance between the rear lock button connector terminals using the tester.

Terminals

No. 3 - No. 4:

When the rear lock button is pushed, did the resistance change from 1 MΩ or more to less than 10 Ω?

Yes : Go to 7.

No : Replace the rear lock button. Ref. to SECURITY AND LOCKS>Rear Lock Button>REMOVAL .
CHECK REAR LOCK BUTTON .
1. Using the Subaru Select Monitor, check the following items in the [Data Monitor] of [Keyless Access with Push Button Start]. Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>DATA MONITOR .
  - [Rear Gate Request SW]
2. Read the data when operating the rear lock button.
Does the data change between ON/OFF?

Yes : Go to 8.

No : Replace the keyless access control module. Ref. to SECURITY AND LOCKS>Keyless Access Control Module>REMOVAL .
CHECK HARNESS (OPEN CIRCUIT) .
1. Disconnect the exterior rear antenna connector and the keyless access control module connector.
2. Using a tester, measure the resistance between the exterior rear antenna connector and keyless access control module connector.
  Connector & terminal
  
  (R299) No. 1 - (i241) No. 8:
  
  (R299) No. 3 - (i241) No. 7:
Is the resistance less than 10 Ω?

Yes : Go to 9.

No : Repair or replace the open circuit of harness.
CHECK HARNESS (GROUND SHORT CIRCUIT) .
1. Disconnect the exterior rear antenna connector and the keyless access control module connector.
2. Using a tester, measure the resistance between the exterior rear antenna connector and chassis ground.
  Connector & terminal
  
  (R299) No. 1 - Chassis ground:
  
  (R299) No. 3 - Chassis ground:
Is the resistance 10 MΩ or more?

Yes : Go to 10.

No : Repair or replace the short circuit of the harness.
CHECK OUTSIDE REAR ANTENNA .
Replace the outside rear antenna with new or properly working parts. Ref. to SECURITY AND LOCKS>Keyless Access Outdoor Antenna>REMOVAL .

Does it operate properly?

Yes : The outside rear antenna has a failure.

No : Go to 11.
CHECK BODY INTEGRATED UNIT .
1. Connect the disconnected connectors.
2. Using the Subaru Select Monitor, check the following items in the [Active Test] of [Body Control]. Ref. to BODY CONTROL (DIAGNOSTICS)>ACTIVE TEST .
  - [lock actuator LOCK output]
3. Actuate the door lock actuator LOCK output.
Does the rear gate lock actuator lock?

Yes : It is possible that temporary poor communication occurs.

No : Go to 12.
CHECK HARNESS (OPEN CIRCUIT) .
1. Disconnect the body integrated unit connector and rear gate lock actuator connector.
2. Measure the resistance between body integrated unit connector and rear gate lock actuator connector.
  Connector & terminal
  
  (i266) No. 7 - (D46) No. 1:
Is the resistance less than 10 Ω?

Yes : Go to 13.

No : Repair or replace the open circuit of harness.
CHECK HARNESS (OPEN CIRCUIT) .
1. Measure the resistance between the rear gate lock actuator connector and chassis ground.
  Connector & terminal
  
  (D46) No. 2 - Chassis ground:
Is the resistance less than 10 Ω?

Yes : Go to 14.

No : Repair or replace the open circuit of harness.
CHECK REAR GATE LOCK ACTUATOR .
1. Check the rear gate lock actuator. Ref. to SECURITY AND LOCKS>Rear Gate Latch and Actuator Assembly>INSPECTION .
Is the check result OK?

Yes : Replace the body integrated unit. Ref. to SECURITY AND LOCKS>BODY INTEGRATED UNIT .

No : Replace the rear gate latch and actuator assembly. Ref. to SECURITY AND LOCKS>REAR GATE LATCH AND ACTUATOR ASSEMBLY .