Electronic Control AWD

DTC U0401: Engine CAN 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 temporarily limits the AWD functions if an abnormality in the throttle opening angle signal is detected.

DTC SET CONDITIONS

If the following conditions are met when the system is in operation (always), AWD-ECU gradually switches the control from AWD to AWD AUTO, flashes the AWD/LOCK indicators alternately, and sets the DTC U0401.

- IG1 voltage: 10 V or more
- Throttle opening angle signal: More than 100%

TROUBLESHOOTING HINTS

Current trouble

- Damaged wiring harness and connectors
- Malfunction of accelerator pedal position sensor
- Malfunction of crankshaft position sensor
- Engine control module malfunction
- AWD-ECU malfunction
Past trouble

- Refer to "How to treat past trouble" (How to Use Troubleshooting/How to Treat Past Trouble How to Treat Past Trouble ) for proceeding the diagnostics. Diagnose mainly wiring harness or connector failure between the engine control module and the accelerator pedal position sensor or between the engine control module and the crank angle sensor.

DIAGNOSIS

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 CAN Bus Diagnostics Chart). Then go to Step 2.
STEP 2. Scan tool MB991958 data list

Check the following data list (Refer to Data List Reference Table).

- Item 08: CAN data (Engine)

Q. Is the check result normal?

YES Go to Step 7.
NO Go to Step 3.
STEP 3. Scan tool MB991958 DTC of other systems

Check if a DTC related to the accelerator pedal position sensor system or the crank angle sensor system is set in the engine control system.

Q. Is the DTC set?

YES Troubleshoot the engine control system Multiport Fuel Injection (MFI)).
NO Go to Step 4.
STEP 4. Scan tool MB991958 DTC of other systems

Check if a DTC, which relates to the CAN communication-linked systems below, is set.

- Meter
U0401: DTC of engine-related failure information

Q. Is the DTC set?

YES Go to Step 5.
NO Go to Step 6.
STEP 5. Check whether the DTC is reset.

Q. Is the DTC U0401 set?

YES Replace the engine control module Removal and Replacement). Then go to Step 7 .
NO A poor connection, open circuit or other intermittent malfunction between the engine control module and the accelerator pedal position sensor, or between the engine control module and the crank angle sensor is suspected How to Cope With Intermittent Malfunctions). Then to Step 6.
STEP 6. 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)Depress the throttle pedal fully.

(4)Check if the DTC is set.

Q. Is the DTC U0401 set?

YES Replace AWD-ECU (Refer to Service and Repair). Then go to Step 7
.
NO A poor connection, open circuit or other intermittent malfunction between the engine control module and the accelerator pedal position sensor, or between the engine control module and the crank angle sensor is suspected How to Cope With Intermittent Malfunctions).
STEP 7. Check whether the DTC is reset.

Q. Is the DTC U0401 set?

YES Diagnose again from Step 1.
NO The procedure is complete.