Wireless Control Module (WCM)

DTC B1A28: Engine control module authenticate error

CAUTION:

- When DTC B1A28 is set, be sure to diagnose the CAN bus line.
- When replacing the ECU, always check that the communication circuit is normal.

DTC SET CONDITION

WCM sets DTC B1A28 when the ignition key certification result and the engine control module starting condition do not match.

TECHNICAL DESCRIPTION (COMMENT)

WCM determines that the abnormality is present, if the key certification result and the engine control module starting condition do not match after the engine start permission communication is completed.

TROUBLESHOOTING HINTS

- Malfunction of CAN bus line
- Malfunction of WCM
- Malfunction of engine control module
- VIN registered in engine control module unmatched

DIAGNOSIS

Required Special Tools:

- MB991958 Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: Vehicle Communication Interface (V.C.I.)
- MB991827 M.U.T.-III USB Cable
- MB991910 M.U.T.-III Main Harness A

STEP 1. Using scan tool MB991958, diagnose the CAN bus line.





(1)
CAUTION:
To prevent damage to scan tool (MB991958), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (MB991958).

Connect scan tool MB991958 to the data link connector.
(2)Turn the ignition switch to the "ON" position.
(3)Diagnose the CAN bus line.
(4)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is the CAN bus line found to be normal?

YES Go to Step 2.

NO Repair the CAN bus line CAN Bus Diagnostics Chart).

STEP 2. Using scan tool MB991958, read the engine control module diagnostic trouble code.

Check again if the DTC is set to the engine control module.

Q. Is the DTC set?

YES Troubleshoot the MFI system Multiport Fuel Injection (MFI)).
NO Go to Step 3.
STEP 3. Using scan tool MB991958, read the diagnostic trouble code.

Check if the DTC is set to the WCM.

(1)Turn the ignition switch from the "LOCK" (OFF) position to the "ON" position.

(2)Check if the DTC is set.

Q. Is DTC B1761 or B2206 set other than B1A28?

YES Perform the troubleshooting for each DTC. Refer to Wireless Control Module (WCM) [B1761] and Wireless Control Module (WCM) [B2206].
NO Go to Step 4.
STEP 4. Recheck for diagnostic trouble code.

Check again if the DTC is set to the WCM.

(1)Turn the ignition switch from the "LOCK" (OFF) position to the "ON" position.

(2)Check if the DTC is set.

Q. Is the DTC set?

YES Replace WCM and register the ID codes (Refer to ID registration procedure manual - ID codes registration judgement table). Then go to Step 5.
NO The diagnosis is complete.
STEP 5. Recheck for diagnostic trouble code.

Check again if the DTC is set to the WCM.

(1)Turn the ignition switch from the "LOCK" (OFF) position to the "ON" position.

(2)Check if the DTC is set.

Q. Is the DTC set?

YES Replace the engine control module and record VIN How to Perform Vehicle Identification Number (VIN) Writing).
NO The procedure is complete.