Code No.U1073 Bus off error
| caution |
If diagnosis code No.U1073 is set in the A/C-ECU, diagnose the CAN main bus line.
|
| caution |
Whenever the ECU is replaced, ensure that the communication circuit is normal.
|
|
|
If the A/C-ECU ceases communicating once (i.e. bus off) and then returns to it, the A/C-ECU will not communicate for three minutes immediately after that point. This three-minute period is called "Penalty mode." Immediately after the A/C-ECU returns to communication, the diagnosis code is set.
|
|
|
COMMENTS ON TROUBLE SYMPTOM
|
|
|
The wiring harness wire or connectors may have loose, corroded, or damage terminals, or terminals pushed back in the connector, or the A/C-ECU may be defective.
|
|
|
- Damaged wiring harness or connectors
- Malfunction of the semi automatic air conditioner control panel (A/C-ECU)
|
|
|
STEP 1. M.U.T.-III CAN bus diagnostics
|
|
|
| warning |
Since the radiator fan rotates during CAN bus line diagnostics, make sure that no one is servicing the engine compartment before diagnosing the CAN bus line. Since the CAN communication stops when diagnosing the CAN bus line, the ETACS-ECU detects the time-out of the engine-ECU, and activates the radiator fan to prevent overheating as fail-safe.
|
|
|
|
Use the 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  ). On completion, go to Step 3.
|
|
|
|
|
|
STEP 2. Check whether the diagnosis code is reset.
|
|
|
Recheck if the diagnosis code is set.
|
|
|
(1)Erase the diagnosis code.
|
|
|
(2)Ignition switch: LOCK (OFF) position to ON
|
|
|
(3)Check if the diagnosis code is set.
|
|
|
Q.
Is the diagnosis code set?
|
|
|
Replace the A/C-ECU, and then go to Step 3.
|
|
|
|
|
|
If a trouble is solved, it is determined that there is an intermittent malfunction such as poor engaged connector(s) or open circuit (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).
|
|
|
|
|
|
STEP 3. Check whether the diagnosis code is reset.
|
|
|
Recheck if the diagnosis code is set.
|
|
|
(1)Erase the diagnosis code.
|
|
|
(2)Ignition switch: LOCK (OFF) position to ON
|
|
|
(3)Check if the diagnosis code is set.
|
|
|
Q.
Is the diagnosis code set?
|
|
|
Return to Step 1.
|
|
|
|
|
|
The procedure is complete.
|
|
|
|