DTC 022: Failures Information on A/C-ECU: 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)

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.
  
  Fig 1: Connecting Scan Tool MB991958 To Data Link Connector
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
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 DIAGNOSIS < Vehicles without advanced air bag > or < Vehicles with advanced air bag >). On completion, go to Step 5.
STEP 2. Using scan tool MB991958, read the A/C-ECU diagnostic trouble code.
Check if an A/C-ECU DTC is set.

Q: Is the DTC set?
1. YES : Refer to DIAGNOSTIC TROUBLE CODE CHART (Manual) or DIAGNOSTIC TROUBLE CODE CHART (Auto) and then Go to Step 3.
2. NO : Go to Step 4.
STEP 3. 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 A/C-ECU and the multi-center display unit (middle grade type) (Refer to HOW TO USE TROUBLESHOOTING/INSPECTION SERVICE POINTS - HOW TO COPE WITH INTERMITTENT MALFUNCTION ).
2. NO : Replace A/C-ECU and then go to step 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 A/C-ECU and the multi-center display unit (middle grade type) (Refer to HOW TO USE TROUBLESHOOTING/INSPECTION SERVICE POINTS - HOW TO COPE WITH INTERMITTENT MALFUNCTION ).
2. NO : Replace multi-center display unit (middle grade type) and then go to step 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 : The procedure is complete. (If no malfunctions are found in all steps, an intermittent malfunction is suspected. Refer to HOW TO USE TROUBLESHOOTING/INSPECTION SERVICE POINTS - HOW TO COPE WITH INTERMITTENT MALFUNCTION ).
2. NO : Go to Step 1.