Code No. U0100: Engine CAN time-out

caution

If more than three minutes elapse after the ignition switch is turned ON without starting engine, 4WD-ECU may set diagnosis code U0100 as past trouble.
If there is any problem in the CAN bus lines, an incorrect diagnosis code 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

4WD-ECU temporarily limits the 4WD functions if it has not received the signal from the engine-ECU.

DIAGNOSIS CODE SET CONDITIONS

If the following conditions are met when the system is in operation (always), 4WD-ECU gradually switches the control from 4WD to 4WD AUTO, flashes the 4WD/LOCK indicators alternately, and sets the diagnosis code No. U0001.

IG1 power supply voltage: 10 V or more
Chassis No. signal, throttle angle signal, or engine speed signal cannot be received.

PROBABLE CAUSES

Current trouble

Wiring harness or connector failure in the CAN bus lines between the engine ECU and 4WD-ECU
Engine ECU malfunction
4WD-ECU malfunction

Past trouble

Refer to "How to treat past trouble" (GROUP 00 - How to Treat Past Trouble

) for proceeding the diagnostics. Diagnose mainly wiring harness or connector failure in the CAN bus lines between the engine ECU and 4WD-ECU, and malfunction in the power supply system for the engine ECU.

note

For a past trouble, you cannot find it by the M.U.T.-III 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 GROUP 00 - How to Cope with Intermittent Malfunction

). You can narrow down the possible cause of the trouble by referring to the diagnosis code, which is set regarding the CAN communication-linked ECUs. (Refer to GROUP 54C - CAN Bus Line Diagnostic Flow

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnostics

Use M.U.T.-III to diagnose the CAN bus lines.

Q. Is the check result normal?

	Go to Step 2.

	Repair the CAN bus line. (Refer to GROUP 54C - Troubleshooting .) Then go to Step 2.

STEP 2. M.U.T.-III Diagnosis code of other systems

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

Q. Is the diagnosis code set?

	Troubleshoot the engine control system. (Refer to GROUP 13A - Troubleshooting .)

	Go to Step 3.

STEP 3. M.U.T.-III Diagnosis code of other systems

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

Meter
U0100: Engine CAN time-out diagnosis code
ETACS
U0100: Engine CAN time-out diagnosis code
A/C
U0100: Engine CAN time-out diagnosis code

Q. Is the diagnosis code set?

	Go to Step 4.

	Go to Step 7.

STEP 4. Check whether the diagnosis code is reset.

(1)Erase the diagnosis code.

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

(3)Check if the diagnosis code is set.

Q. Is the diagnosis code No. U0100 set?

	Replace the engine-ECU. (Refer to GROUP 13A - Engine-ECU .) Then go to Step 8.

	A poor connection, open circuit or other intermittent malfunction in the CAN bus lines between the engine ECU and the 4WD-ECU is suspected. (Refer to GROUP 00 - How to Cope with Intermittent Malfunction .) Then go to Step 5 .

STEP 5. Check the following connector:

Check the connectors below for improper engagement, terminal damage or terminal drawn in the connector case.

C-130 4WD-ECU connector
C-313, C-317 ETACS-ECU connector

Q. Are the connectors and terminals in good condition?

	Go to Step 6.

	Repair the connector(s) or terminal(s). Then go to Step 8.

STEP 6. Wiring harness check

Check the wiring harness between the C-130 4WD-ECU connector and the C-313 ETACS-ECU connector for damage or other problem.

Q. Is the wiring harness in good condition?

	Go to Step 7.

	Repair damage or other problem in the wiring harness. Then go to Step 8.

STEP 7. Check whether the diagnosis code is reset.

Q. Is the diagnosis code No. U0100 set?

	Replace 4WD-ECU. (Refer to .) Then go to Step 8.

	A poor connection, open circuit or other intermittent malfunction in the CAN bus lines between the engine ECU and 4WD-ECU is suspected. (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).

STEP 8. Check whether the diagnosis code is reset.

Q. Is the diagnosis code No. U0100 set?

	Diagnose again from Step 1.

	This diagnosis is complete.