DTC B2402: STL unit comm. (system ID),
DTC B2403: STL unit comm. (CRC),
DTC B2404: STL unit comm. (function code),
DTC B2405: STL unit comm. (rolling code),
DTC B2406: STL unit comm. (PTC operate),
DTC B2407: STL unit comm. (EEPROM),
DTC B2408: STL unit comm. (solenoid)

caution

If the DTC B2402, B2403, B2404, B2405, B2406, B2407, or B2408 is set, diagnose the CAN bus lines.
Whenever the steering lock unit is replaced, ensure that the communication circuit is normal.

DTC SET CONDITION

When the ignition push switch is pressed, the steering lock unit communicates with KOS-ECU to unlock the IG knob. However, if there is a failure shown below, the corresponding DTC is set.

B2402: System ID (vehicle specific code) failure
B2403: Cyclic Redundancy Check (CRC): The error detection strategy to detect a continuously occurring error (burst error), the calculation result discrepancy
B2404: Function code failure
B2405: Rolling code (automatically changing a code for lock/unlock each time when a lock operation is performed)
B2406: PTC thermistor continuously activated or activated to prevent solenoid abnormal heating on the communication with steering lock unit
B2407: EEPROM failure
B2408: Communication error between the steering lock unit and KOS-ECU, or solenoid failure

TECHNICAL DESCRIPTION (COMMENT)

Range of check

When the IG knob unlock communication is performed by pressing the ignition push switch

Judgement criteria

B2402: Steering lock unit communication error (system ID) or received system ID error
B2403: Steering lock unit communication error (CRC) or received frame CRC calculation result discrepancy
B2404: Steering lock unit communication error (function code) or received frame function code undefined
B2405: Steering lock unit communication error (rolling code) or received rolling code out of the permissible range
B2406: Steering lock unit communication error (PTC operation) or PTC thermistor activated to prevent solenoid abnormal heating
B2407: Steering lock unit communication error (EEPROM) or RRPROM failure
B2408: Steering lock unit communication error (solenoid) or solenoid failure

TROUBLESHOOTING HINTS

Malfunction of the key reminder switch (integrated into the steering lock unit)
Wiring harness or connector failure of CAN bus line
Malfunction of the KOS-ECU

DIAGNOSIS

Required Special Tools:

MB991958: Scan Tool (M.U.T.-III Sub Assembly)

MB991824: Vehicles Communication Interface (V.C.I.)
MB991827: M.U.T.-III USB Cable
MB991910: M.U.T.-III Main Harness A (Vehicles with CAN communication system)

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?

Go to Step 2.

Repair the CAN bus line. (Refer to GROUP 54C - Diagnosis

STEP 2. Check key reminder switch connector C-213 and KOS-ECU connector C-31 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q. Is the key reminder switch connector C-213 and KOS-ECU connector C-31 in good condition?

	Go to Step 3.

	Repair the defective connector.

STEP 3. Check the wiring harness between the key reminder switch connector C-213 (terminal No. 12, 9) and the KOS-ECU connector C-31 (terminal No. 4, 5).

Check the signal lines for open circuit and short circuit.

Q. Is the wiring harness between key reminder switch connector C-213 (terminal No. 12, 9) and the KOS-ECU connector C-31 (terminal No. 4, 5) in good condition?

	Go to Step 4.

	The wiring harness may be damaged or the connector(s) may have loose, corroded or damaged terminals, or terminals pushed back in the connector. Repair the wiring harness as necessary.

STEP 4. Replace the key reminder switch, and check whether the diagnostic trouble code is reset.

(1)Erase the DTC.

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

(3)Check if the DTC is set.

Q. Is the DTC set?

	Replace KOS-ECU and register the ID codes. (Refer to .)

	The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to use Troubleshooting/inspection Service Points - How to Cope with Intermittent Malfunction ).

DTC B2402: STL unit comm. (system ID), DTC B2403: STL unit comm. (CRC), DTC B2404: STL unit comm. (function code), DTC B2405: STL unit comm. (rolling code), DTC B2406: STL unit comm. (PTC operate), DTC B2407: STL unit comm. (EEPROM), DTC B2408: STL unit comm. (solenoid)