Electronic Control AWD

DTC U0100: Engine CAN timeout

CAUTION:

- If more than three minutes elapse after the ignition switch is turned "ON" without starting engine, AWD-ECU may set DTC U0100 as past trouble.

- 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 it has not received the signal from the engine control module.

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 U0001.

- IG1 power supply voltage: 10 V or more

- Chassis No. signal, throttle angle signal, or engine speed signal cannot be received.

TROUBLESHOOTING HINTS

Current trouble

- Wiring harness or connector failure in the CAN bus lines between the engine control module and AWD-ECU

- Engine control module malfunction

- AWD-ECU malfunction
Past trouble

- Refer to 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 in the CAN bus lines between the engine control module and AWD-ECU, and malfunction in the power supply system for the engine control module.
NOTE:
For a past trouble, you cannot find it by the scan tool MB991958 CAN bus diagnostics even if there is any failure in CAN bus lines. In this case, check the CAN bus lines in the same manner as How to cope with intermittent malfunction (refer to How to Use Troubleshooting - How to Cope with Intermittent Malfunction How to Cope With Intermittent Malfunctions). You can narrow down the possible cause of the trouble by referring to the DTC, which is set regarding the CAN communication-linked ECUs. CAN Bus Line Diagnostics Flow.)

DIAGNOSIS

Required Special Tools:

- 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 CAN Bus Diagnostics Chart). Then go to Step 2.
STEP 2. Scan tool MB991958 DTC of other systems

Check that the bus-off error DTC is set in the engine control system.

Q. Is the DTC set?

YES Troubleshoot the engine control system Multiport Fuel Injection (MFI) [4B12]).
NO Go to Step 3.
STEP 3. Scan tool MB991958 DTC of other systems

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

- Combination meter
U0100: Engine CAN timeout DTC

- ETACS
U0100: Engine CAN timeout DTC

Q. Is the DTC set?

YES Go to Step 4.
NO Go to Step 5.
STEP 4. 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 U0100 set?

YES Replace the engine control module Removal and Replacement [4B12]). Then go to Step 6 .
NO A poor connection, open circuit or other intermittent malfunction in the CAN bus lines between the engine control module and the AWD-ECU is suspected How to Cope With Intermittent Malfunctions).
Then go to Step 5
STEP 5. Check whether the DTC is reset.

Q. Is the DTC U0100 set?

YES Replace AWD-ECU (Refer to Electronic Control AWD). Then go to Step 6 .
NO A poor connection, open circuit or other intermittent malfunction in the CAN bus lines between the engine control module and AWD-ECU is suspected How to Cope With Intermittent Malfunctions).
STEP 6. Check whether the DTC is reset.

Q. Is the DTC U0100 set?

YES Diagnose again from Step 1.
NO This diagnosis is complete.