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DTC U0101: TCM Time-out <CVT>

 
 
caution
  • If the ECM output the DTC U0101, make sure to diagnose the CAN bus line.
  • Before replacing the ECU, make sure that the communication circuit is operating normally.
 
 
DESCRIPTIONS OF MONITOR METHODS
  • There is no data from TCM for the specified time. (TCM also detect communication error with ECM.)
 
 
MONITOR EXECUTION
  • Continuous
 
 
MONITOR EXECUTION CONDITIONS (Other monitor and Sensor)
Other Monitor (There is no temporary DTC stored in memory for the item monitored below)
  • Not applicable
Sensor (The sensor below is determined to be normal)
  • Not applicable
 
 
DTC SET CONDITIONS
Logic Flow Chart
Check Condition
  • Battery positive voltage is between 10 and 16.5 volts.
Judgment Criterion
  • Unable to receive TCM signals through the CAN bus line for 4 seconds.
 
 
COMMENT
Current Trouble
  • Some of the possible causes are a harness or connector damage between the ECM and the TCM on the CAN bus line, a failure in the TCM power supply system, a failure in the TCM, or a failure in the ECM.
Past Trouble
  • Proceed to troubleshoot based on a harness or connector damage on the CAN bus line between the ECM and TCM, and a failure in the TCM power supply system. Refer to "How to cope with past trouble" (Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Treat Past Trouble ).
noteIf a malfunction occurred in the past, a failure cannot be discovered through the scan tool (M.U.T.-III) CAN bus diagnosis even if there might be a problem with the CAN bus. In this case, refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions . Furthermore, it is possible to narrow down the areas of the possible failures from the DTCs that are output by the ECUs, which are communicating on the CAN bus [Refer to GROUP 54C, Explanation about the Scan Tool (M.U.T.-III) CAN Bus Diagnostics ].
 
 
FAIL-SAFE AND BACKUP FUNCTION
  • None
 
 
OBD-II DRIVE CYCLE PATTERN
  • None.
 
 
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
  • CAN line harness damage or connector damage.
  • TCM failed.
  • ECM failed.

 
 
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. Using scan tool (M.U.T.-III), diagnose CAN bus line.
cautionTo 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).
(1) Connect scan tool (M.U.T.-III). Refer to HOW TO CONNECT THE SCAN TOOL (M.U.T.-III) .
(2) Turn the ignition switch to the "ON" position.
(3) Diagnose CAN bus line.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is the CAN bus line normal?
Go to Step 2.
Repair the CAN bus line. Refer to GROUP 54C, Diagnosis - CAN Bus Diagnostics Table . Then go to Step 6.
 
STEP 2. Using scan tool (M.U.T.-III), read the diagnostic trouble code (DTC).
(1) Turn the ignition switch to the "ON" position.
(2) Read the TCM-DTC.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Is the CVT-DTC set?
Refer to GROUP 23A, Diagnosis - Diagnostic Trouble Code Chart .
Go to Step 3.
 
STEP 3. Using scan tool (M.U.T.-III), read the diagnostic trouble code (DTC).
(1) Turn the ignition switch to the "ON" position.
(2) Read the ASC-DTC and ETACS-DTC.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Is DTC U0101 set?
Go to Step 4.
Go to Step 5.
 
STEP 4. Using scan tool (M.U.T.-III), read the diagnostic trouble code (DTC).
(1) Turn the ignition switch to the "ON" position.
(2) After the MFI-DTC has been deleted, read the MFI-DTC again.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Is DTC U0101 set?
Replace the TCM. Then go to Step 6.
It can be assumed that this malfunction is intermittent of CAN bus line between ECM and TCM. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions .
 
STEP 5. Using scan tool (M.U.T.-III), read the diagnostic trouble code (DTC).
(1) Turn the ignition switch to the "ON" position.
(2) After the MFI-DTC has been deleted, read the MFI-DTC again.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Is DTC U0101 set?
Replace the ECM (Refer to, Removal and Installation ). Then go to Step 6.
It can be assumed that this malfunction is intermittent of CAN bus line between ECM and TCM. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions .
 
STEP 6. Using scan tool (M.U.T.-III), read the diagnostic trouble code (DTC).
(1) Turn the ignition switch to the "ON" position.
(2) After the MFI-DTC has been deleted, read the MFI-DTC again.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Is DTC U0101 set?
Retry the troubleshooting.
The inspection is complete.