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 receives the data (such as drive mode display signal, failure information signal) from ETACS-ECU via the CAN bus lines. If it cannot receive such data, illuminates the 4WD indicator.
DIAGNOSIS CODE SET CONDITIONS
If the following conditions are met when the system is in operation (always), 4WD-ECU flashes the 4WD/LOCK indicators alternately, and sets the diagnosis code No. U0141.
IG1 power supply voltage: 8 V or more
The signal output from ETACS-ECU cannot be received.
PROBABLE CAUSES
Current trouble
Wiring harness or connector failure in the CAN bus lines between ETACS-ECU and 4WD-ECU
Malfunction of ETACS-ECU
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 ETACS-ECU and 4WD-ECU, and malfunction in the power supply system for ETACS-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 data list
Check the following service data. (Refer to .)
Item 09: CAN system (ETACS)
Q.
Is the check result normal?
Go to Step 6.
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 U0141: ETACS CAN time-out diagnosis code
A/C U0141: ETACS CAN time-out diagnosis code
Engine U0141: ETACS CAN time-out diagnosis code
Q.
Is the diagnosis code set?
Go to Step 4.
Go to Step 5.
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. U0141 set?
Replace ETACS-ECU. Then go to Step 6.
A poor connection, open circuit or other intermittent malfunction in the CAN bus lines between ETACS-ECU and 4WD-ECU is suspected. (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).
STEP 5. 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. U0141 set?
Replace 4WD-ECU. (Refer to .) Then go to Step 6.
A poor connection, open circuit or other intermittent malfunction in the CAN bus lines between ETACS-ECU and 4WD-ECU is suspected. (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).
STEP 6. Check whether the diagnosis code is reset.