The TCM determines that a fault has occurred when it receives an error signal from the ASC-ECU.
DTC SET CONDITIONS
Check Condition
Ignition switch is "ON" position
DTC: U0121 CAN time-out error (ASC) is not detected.
Judgment Criteria
This ECU receives an error signal from the ASC-ECU for 2 seconds.
PROBABLE CAUSES
Malfunction of ASC system
Malfunction of TCM
DIAGNOSIS
Required Special Tools:
MB992744: Vehicle communication interface-Lite (V.C.I.-Lite)
MB992745: V.C.I.-Lite main harness A
MB992747: V.C.I.-Lite USB cable short
MB992748: V.C.I.-Lite USB cable long
MB991958: Scan Tool (M.U.T.-III Sub Assembly)
MB991824: Vehicles Communication Interface (V.C.I.)
MB991827: M.U.T.-III USB Cable
MB991910: M.U.T.-III Main Harness A (Vehicles with CAN communication system)
STEP 1. Use scan tool (M.U.T.-III) to check the DTC of other systems.
caution
To prevent damage to scan tool (M.U.T.-III), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-III).
Check if ASC-related DTC is stored.
Is the ASC-related DTC stored?
Carry out the appropriate troubleshooting (Refer to GROUP 35C, Diagnosis - Diagnostic Trouble Code Chart ).
Go to Step 2.
STEP 2. Symptom recheck after erasing DTC.
Is the DTC stored?
Replace the TCM (Refer to ).
Intermittent malfunction (Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).