A/T
DTC U0121: ABS/ASC-ECU Time OutDESCRIPTIONS OF MONITOR METHODS
^ Open circuit or short circuit occurs in the CAN communication line (CAN_H, CAN_L).
^ Reception from ABS/ASC-ECU becomes impossible for a specified time or more.
TROUBLESHOOTING HINTS (THE MOST LIKELY CAUSES FOR THIS CODE TO BE SET ARE:)
^ Damaged harness or connector
^ Malfunction of the CAN communication
^ Malfunction of the ABS/ASC-ECU
^ Malfunction of the TCM
DIAGNOSIS
STEP 1. Check the CAN communication system malfunction.
^ Check that the CAN system-related DTC code other than U0121 is set.
^ Check if the CAN-related DTC is set with ABS/ASC-ECU.
^ Check if the failure related to the ABS/ASC occurs.
Q:Is the check result normal?
YES: Go to Step 2.
NO: Repair or replace the failure section.
STEP 2. Check the CAN communication lines.
[C-38 TCM connector (vehicle side, disconnected)]
Between C-38 terminal No. 10, 11 and the CAN communication lines of ABS/ASC-ECU: Continuity exists.
When the continuity check result is OK, check that the wiring harness is not shorted to the body and other wiring harness. Also, check for a short circuit between the twisted pair cables.
Q:Is the check result normal?
YES: Go to Step 3.
NO: Repair or replace the failure section.
STEP 3. Check the ABS/ASC-ECU, the TCM connector pin terminal, and the connection status.
Q:Is the check result normal?
YES: Repair or replace the failure section.
NO: Replace the TCM.