Code No. P1A23: EV-ECU mode unstable (MCU)


caution 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.

DIAGNOSIS CODE SET CONDITIONS


If the EV-ECU control mode is kept unstable when the electric motor switch is set to the ON position, the MCU will set the diagnosis code No. P1A23.

PROBABLE CAUSES



DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnosis
Use the M.U.T.-III to diagnose the CAN bus lines.

Q. Is the check result normal?
Go to Step 3.
Repair the CAN bus line. (Refer to GROUP 54C - Troubleshooting .) Then go to Step 2.

STEP 2. Check whether the diagnosis code is reset.
Check again if the diagnosis code No. P1A23 is set to the MCU.
(1)Erase the stored diagnosis code.
(2)Set the electric motor switch from the LOCK (OFF) position to the ON position.
(3)Check if the diagnosis code is set.

Q. Is the diagnosis code set?
Go to Step 3.
This diagnosis is complete.

STEP 3. M.U.T.-III Diagnosis code of other systems
Check if the diagnosis code is set to the EV-ECU.

Q. Is the diagnosis code set?
Carry out troubleshooting for the EV-ECU. (Refer to .) Then go to Step 4.
Go to Step 4.

STEP 4. Diagnosis code recheck
Check again if the diagnosis code is set to the MCU.
(1)Erase the stored diagnosis code.
(2)Set the electric motor switch from the LOCK (OFF) position to the ON position.
(3)Check if the diagnosis code is set.

Q. Is the diagnosis code set?
Replace the MCU. (Refer to .) Then go to Step 5.
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction .)

STEP 5. Diagnosis code recheck
Check again if the diagnosis code is set to the MCU.
(1)Erase the stored diagnosis code.
(2)Set the electric motor switch from the LOCK (OFF) position to the ON position.
(3)Check if the diagnosis code is set.

Q. Is the diagnosis code set?
Return to Step 1.
The diagnosis is complete.




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