U113C

DTC U113C: Wheel speed sensor data error

CAUTION:
^ If there is any problem in the CAN bus lines, an incorrect DTC may be set. Prior to this diagnosis, always diagnose the CAN bus lines.
^ Before replacing the ECU, ensure that the communication circuit is normal.

OPERATION
AWD-ECU receives the data (such as ABS sensor signal, ABS operation signal) via the CAN bus lines. If it cannot receive such data, it interrupts the system.

DTC SET CONDITIONS
If the following conditions are met when the system is activated, AWD-ECU gradually switches the control from AWD to FWD, flashes the AWD/LOCK indicators alternately, and sets the DTC No. U113C.

^ IG1 voltage: 8 V or more
^ ABS signal (such as wheel speed signal) cannot be received.
^ DTC No.00121 ABS CAN time-out is not detected.

TROUBLESHOOTING HINTS

Current trouble
^ Wiring harness or connector failure between ASC-ECU and the stop lamp switch
^ Malfunction of the ABS sensor
^ Malfunction of the stop lamp switch
^ ASC-ECU malfunction
^ AWD-ECU malfunction

Past trouble
^ Refer to "How to treat past trouble" for proceeding the diagnostics. Diagnose mainly wiring harness or connector failure in the CAN bus lines between ASC-ECU and each ABS sensor, or between ASC-ECU and the stop lamp switch.

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

STEP 1. Scan tool MB991958 CAN bus diagnostics
Use scan tool MB991958 to diagnose the CAN bus lines.

Q:Is the check result normal?
YES: Go to Step 2.
NO: Repair the CAN bus line. Then go to Step 2.

STEP 2. Scan tool MB991958 DTC of other systems
Check the following service data.

^ Item 07: CAN system (ABS/ASC)
^ Item 16: FL wheel speed sensor
^ Item 17: FR wheel speed sensor
^ Item 18: RL wheel speed sensor
^ Item 19: RR wheel speed sensor

Q:Is the DTC set?
YES: Troubleshoot the ABS system.
NO: Go to Step 3.

STEP 3. Check whether the DTC 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 No. U113C set?
YES: Replace AWD-ECU. Then go to Step 4.
NO: A poor connection, open circuit or other intermittent malfunction in the CAN bus lines between ASC-ECU and each ABS sensor, or between ASC-ECU and the stop lamp switch is suspected.

STEP 4. Check whether the DTC is reset.

Q:Is the DTC No. U113C set?
YES: Diagnose again from Step 1.
NO: This diagnosis is complete.