Code No. P1A18: MCU shutdown circuit


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.
ELECTRIC MOTOR UNIT CONTROL SYSTEM CIRCUIT





OPERATION



  • The EV-ECU controls the IGBT gate in the MCU by outputting the gate shutdown signal to the MCU. The MCU also transmits the input status of the gate shutdown signal to the EV-ECU as a feedback signal by means of the CAN signal.

DIAGNOSIS CODE SET CONDITIONS



  • If the gate shutdown signal commanded by the EV-ECU differs from the feedback signal received from the MCU for 1 second or longer, the diagnosis code No. P1A18 will be set.

PROBABLE CAUSES



  • Damaged wiring harness or connector(s)
  • Malfunction of the MCU

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. Diagnosis code recheck after resetting CAN bus lines
Check again if the diagnosis code No. P1A18 is set to the EV-ECU.
(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. Connector check: E-06 MCU connector, C-111 EV-ECU connector

Q. Is the check result normal?
Go to Step 4.
Repair the damaged connector.

STEP 4. Check the wiring harness between E-06 MCU connector terminal No. 4 and C-111 EV-ECU connector terminal No. 117.
Check the signal lines for open circuit and short to earth.

Q. Is the check result normal?
Go to Step 5.
Repair the wiring harness.

STEP 5. Diagnosis code recheck
Check again if the diagnosis code is set to the EV-ECU.
(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 6.
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction .)

STEP 6. Diagnosis code recheck
Check again if the diagnosis code is set to the EV-ECU.
(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.