If there is any problem in
the CAN bus lines, an incorrect diagnosis code may be set. Prior to this diagnosis, diagnose
the CAN bus lines .
OPERATION
ASC-ECU communicates with EV-ECU via CAN.
DIAGNOSIS CODE SET CONDITIONS
If the ASC/TCL torque request information
received from the ASC-ECU via the CAN is abnormal, diagnosis code No. P1231 will be set.
PROBABLE CAUSES
Wiring harness or connector failure of CAN bus line
ASC-ECU malfunction
EV-ECU malfunction
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 - CAN Bus Diagnostics Table ).
STEP 2. Diagnosis code recheck after resetting CAN bus lines
Recheck if the diagnosis code is set .
(1)Erase the diagnosis code.
(2)Turn the electric motor switch from "LOCK" (OFF) position to "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 other system diagnosis code
Check if diagnosis code is set to the ASC-ECU.
Q.
Is the diagnosis code set?
Troubleshoot the ASC (Refer to GROUP 35C - Diagnosis Code Chart ).
Then go to STEP 5.
Go to Step 4
STEP 4. Check whether the diagnosis code is reset
Recheck if the diagnosis code is set .
(1)Erase the diagnosis code.
(2)Turn the electric motor switch from "LOCK" (OFF) position to "ON" position.
(3)Check if the diagnosis code is set.
Q.
Is the diagnosis code set?
Replace the EV-ECU (Refer to ).
The trouble can be an intermittent malfunction such as a poor connection or open
circuit in the CAN bus lines between the ASC-ECU and the EV-ECU (GROUP 00 - How to
use Troubleshooting/inspection Service Points - How to Cope with Intermittent
Malfunctions ).
STEP 5. Check whether the diagnosis code is reset
Recheck if the diagnosis code is set .
(1)Erase the diagnosis code.
(2)Turn the electric motor switch from "LOCK" (OFF) position to "ON" position.
Go to Step 2
Repair the CAN bus line (Refer to GROUP 54C - CAN Bus Diagnostics Table 
).