DTC U1120: Failure Information on Powertrain Control Module (Related to Engine): Diagnosis

Required Special Tools: 

• MB991958: Scan Tool (MUT-III Sub Assembly)
  • MB991824: Vehicle Communication Interface (V.C.I.)
  • MB991827: MUT-III USB Cable
  • MB991910: MUT-III Main Harness A (Vehicles with CAN communication system)

1. 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? 

   1. YES:  Go to Step 2.
   2. NO:  Repair the CAN bus lines (Refer to CAN BUS DIAGNOSTIC CHART ). On completion, go to  Step 6.
      Fig 1: Connecting Scan Tool MB991958 To Data Link Connector

      Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
2. 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? 

   1. YES:  Diagnose the MFI system by referring to DIAGNOSTIC TROUBLE CODE CHART or DIAGNOSTIC TROUBLE CODE CHART .
   2. NO:  Go to Step 3.
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 >

   • Multi-center display

     DTC 020: Failure information on powertrain control module (related to engine)

   • A/C-ECU

     DTC U1120: Failure information on powertrain control module (related to engine)

   Q: Is the DTC set? 

   1. YES:  Go to Step 4.
   2. NO:  Go to  Step 5.
4. 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 check result satisfactory? 

   1. YES:  A poor connection, open circuit or other intermittent malfunction is present in the lines between the powertrain control module and the combination meter (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTIONS ).
   2. NO:  Replace powertrain control module and then go to  Step 6.
5. 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 check result satisfactory? 

   1. YES:  A poor connection, open circuit or other intermittent malfunction is present in the lines between the powertrain control module and the combination meter (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTIONS ).
   2. NO:  Replace combination meter and then go to step 6.
6. 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 check result satisfactory? 

   1. YES:  The procedure is complete.
   2. NO:  Go to  Step 1.