Failure Information on Powertrain Control Module (Related to Engine)
DTC U1120: Failure Information on Powertrain Control Module (Related to Engine)CAUTION:
- If DTC U1120 is set in the multi-center display unit (middle grade type), diagnose the CAN main bus line.
- The engine control system- related DTC may be set when DTC U1120 is set. (For details, refer to Intersystem Affiliated DTC reference table).Diagnose the engine control system first when the engine control system- related DTC is set.
- Before replacing the multi-center display unit (middle grade type), ensure that the power supply circuit and the ground circuit are normal.
DTC SET CONDITION
The multi-center display unit (middle grade type) communicates with the powertrain control module via CAN bus line. If failure information is sent to the powertrain control module, DTC U1120 will be set.
TECHNICAL DESCRIPTION (COMMENT)
Current trouble
- The powertrain control module or the multi-center display unit (middle grade type) may be defective.
Past trouble
- Carry out diagnosis with particular emphasis on connector(s) or wiring harness between the powertrain control module and the multi-center display unit (middle grade type).
TROUBLESHOOTING HINTS
- The wiring harness or connectors may have loose, corroded, or damaged terminals, or terminals pushed back in the connector
- Malfunction of powertrain control module
- Malfunction of multi-center display unit (middle grade type)
DIAGNOSIS
Required Special Tools:
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: Vehicle 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 MB991958, diagnose the CAN bus line.
Use scan tool MB991958 to diagnose the CAN bus lines.
1. Connect scan tool MB991958 to the data link connector.
2. Turn the ignition switch to "ON" position.
3. Diagnose the CAN bus line.
Q: Is the check result satisfactory?
YES : Go to Step 2.
NO : Repair the CAN bus lines. On completion, go to Step 6.
STEP 2. Using scan tool MB991958, read the MFI system diagnostic trouble code.
Check if an MFI system DTC is set.
Q: Is the DTC set?
YES :Diagnose the MFI system by referring to MFI Diagnosis - Diagnostic Trouble Code Chart [2.4L ENGINE] Diagnostic Trouble Code Descriptions or MFI Diagnosis - Diagnostic Trouble Code Chart [3.8L ENGINE]. Diagnostic Trouble Code Descriptions
NO : Go to Step 3.
STEP 3. Using scan tool MB991958, read the diagnostic trouble code related to the other system.
Check if a DTC, which relates to CAN communication-linked systems below, is set.
- ABS-ECU
DTC U1120: Failure information on powertrain control module (related to engine) [Vehicles with TCL]
- A/C-ECU
DTC U1120: Failure information on powertrain control module (related to engine)
Q: Is the DTC set?
YES : Go to Step 4.
NO : Go to Step 5.
STEP 4. Recheck for diagnostic trouble code.
Recheck if the DTC is set.
1. Erase the DTC.
2. Turn the ignition switch to "ON" position.
3. Check if the DTC is set.
Q: Is the DTC set?
YES : Replace powertrain control module and then go to step 6.
NO : A poor connection, open circuit or other intermittent malfunction is present in the lines between the powertrain control module and the multi-center display unit (middle grade type).
STEP 5. Recheck for diagnostic trouble code.
Recheck if the DTC is set.
1. Erase the DTC.
2. Turn the ignition switch to "ON" position.
3. Check if the DTC is set.
Q: Is the DTC set?
YES : Replace multi-center display unit (middle grade type) and then go to step 6.
NO : A poor connection, open circuit or other intermittent malfunction is present in the lines between the powertrain control module and the multi-center display unit (middle grade type).
STEP 6. Recheck for diagnostic trouble code.
Recheck if the DTC is set.
1. Erase the DTC.
2. Turn the ignition switch to "ON" position.
3. Check if the DTC is set.
Q: Is the DTC set?
YES : Go to Step 1.
NO : The procedure is complete.