DTC B2784: Antenna Circuit (Push Engine Switch)

DTC detecting condition:

When the keyless access control module received erroneous data for the antenna coil from the transponder key amplifier through the transponder communication (communication between keyless access control module - push button ignition switch) upon the transponder collation start operation.

Trouble symptom:

Power supply does not switch and engine does not start, even when the access key is pointed toward the vehicle.

CAUTION:

For replacement procedure of keyless access control module, refer to the "REGISTRATION INSTRUCTIONS FOR IMMOBILIZER" provided as a separate volume.
Before performing diagnosis, refer to "CAUTION" in "General Description". Refer to KEYLESS ACCESS WITH PUSH BUTTON START SYSTEM (DIAGNOSTICS)>GENERAL DESCRIPTION>CAUTION .

Wiring diagram:

Immobilizer system. Refer to WIRING SYSTEM>IMMOBILIZER SYSTEM>WIRING DIAGRAM .

Courtesy of SUBARU OF AMERICA, INC.

CHECK HARNESS (OPEN CIRCUIT).
1. Disconnect the push button ignition switch connector.
2. Disconnect the keyless access control module connector.
3. Using a tester, measure the resistance between the push button ignition switch connector and the keyless access control module connector.
  Connector & terminal
  
  (i150) No. 9 - (B574) No. 19:
  
  (i150) No. 10 - (B574) No. 22:
  
  (i150) No. 14 - (B574) No. 21:
  
  (i150) No. 8 - (B574) No. 24:
  
  Is the resistance less than 1 Ω?
  
  Yes: Go to 2.
  
  No: Repair or replace the open circuit of harness.
CHECK HARNESS (GROUND SHORT CIRCUIT).
Using a tester, measure the resistance between the push button ignition switch connector and chassis ground.

Connector & terminal

(i150) No. 14 - Chassis ground:

(i150) No. 9 - Chassis ground:

(i150) No. 10 - Chassis ground:

Is the resistance 10 kΩ or more?

Yes: Go to 3.

No: Repair or replace the short circuit of the harness.
CHECK PUSH BUTTON IGNITION SWITCH.
1. Replace the push button ignition switch. Refer to SECURITY AND LOCKS>PUSH BUTTON IGNITION SWITCH .
2. Perform the clear memory for «Keyless Access with Push Button Start» using the Subaru Select Monitor. Refer to KEYLESS ACCESS WITH PUSH BUTTON START SYSTEM (DIAGNOSTICS)>CLEAR MEMORY .
3. Read DTCs of «Keyless Access with Push Button Start» using the Subaru Select Monitor. Refer to KEYLESS ACCESS WITH PUSH BUTTON START SYSTEM (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .
  Is DTC B2784 displayed? (Current malfunction)
  
  Yes: Replace the keyless access control module. Refer to SECURITY AND LOCKS>KEYLESS ACCESS control module .
  
  No: Malfunction occurred in the push button ignition switch.