DTC B2788: IGN Signal Correlation (Steering Lock Control Module)

WARNING: This page is about a different car, the 2022 Subaru WRX. However, it is still accessible from the selected car via links, so may be relevant.

DTC detecting condition:

When one second elapses while the ignition switch status is not compatible between LIN communication and direct line.

Trouble symptom:

The steering lock cannot be released.

Wiring diagram:

Keyless access with push button start system Ref. to WIRING SYSTEM>KEYLESS ACCESS WITH PUSH BUTTON START SYSTEM>WIRING DIAGRAM

Courtesy of SUBARU OF AMERICA, INC.

CAUTION:

For replacement procedure of keyless access control module and steering lock control module, 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 FUSE .
Check the fuse. Ref. to WIRING SYSTEM>KEYLESS ACCESS WITH PUSH BUTTON START SYSTEM>WIRING DIAGRAM

Is the check result OK?

Yes : Go to 2.

No : Replace the fuse. When the replaced fuse is blown immediately, check the power supply circuit for short-circuited.
CHECK DATA MONITOR .
1. Turn the ignition switch to ON.
2. Using the Subaru Select Monitor, check the following items in the [Data Monitor] of [Keyless Access with Push Button Start (Power Supply)]. Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>DATA MONITOR
  - IGN1/2 relay monitor (drive output)
Is the display normal according to the ignition switch operation?

Yes : Go to 3.

No : Go to 5.
CHECK HARNESS (OPEN CIRCUIT) .
1. Turn the ignition switch to OFF.
2. Disconnect the connector from the steering lock control module.
3. Using a tester, measure the resistance between the steering lock control module connector and chassis ground.
  Connector & terminal
  
  (i89) No. 1 - Chassis ground:
Is the resistance less than 1 Ω?

Yes : Go to 4.

No : Repair or replace the open circuit of harness.
CHECK HARNESS .
1. Connect the connector from the steering lock control module.
2. Using a tester, measure the voltage between the steering lock control module connector terminals.
  Connector & terminal
  
  (i89) No. 6 (+) - (i89) No. 1 (-):
Is the voltage 9.5 V or more when the ignition is ON?

Is the voltage less than 1 V with IG OFF?

Yes : Replace the steering lock control module. Ref. to SECURITY AND LOCKS>STEERING LOCK CONTROL MODULE>REPLACEMENT

No : Check the DC power supply circuit.
CHECK DTC .
1. Turn the ignition switch to ON.
2. Read the DTC of [Keyless Access with Push Button Start (Power Supply)] using the Subaru Select Monitor. Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC)
Is DTC B2271 displayed? (Current code)

Yes : Perform the diagnosis of DTC B2271. Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)>DTC B2271 IGN RELAY CONTROL CIRCUIT

No : Replace the keyless access control module. Ref. to SECURITY AND LOCKS>KEYLESS ACCESS CONTROL MODULE>REMOVAL