DTC 22
DTC 22: Failures Information on A/C-ECUCAUTION:
- If DTC 22 is set in the multi-center display, always diagnose the CAN bus lines.
- Before replacing the multi-center display, ensure that the power supply circuit and the ground circuit are normal. (Check that the voltage is 10 V or more.)
DTC SET CONDITION
The multi-center display communicates with the A/C-ECU via CAN bus lines. If the A/C-ECU sends failure information, DTC 22 will be set.
TECHNICAL DESCRIPTION (COMMENT)
Current trouble
- The A/C-ECU or the multi-center display may be defective.
Past trouble
- Carry out diagnosis with particular emphasis on connector(s) or wiring harness between the A/C-ECU and the multi-center display.
TROUBLESHOOTING HINTS
- The wiring harness or connectors may have loose, corroded, or damaged terminals, or terminals pushed back in the connector.
- Malfunction of A/C-ECU
- Malfunction of ambient temperature sensor
- Malfunction of multi-center display
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 5.
STEP 2. Using scan tool MB991958, read A/C-ECU diagnostic trouble code.
Check if an A/C-ECU DTC is set.
Q: Is the DTC set?
YES :Diagnose the A/C system by referring to Manual A/C Diagnosis - Diagnostic Trouble Code Chart Diagnostic Trouble Code Descriptions or Auto A/C Diagnostic Trouble Code Chart. Diagnostic Trouble Code Descriptions
NO : Go to Step 3.
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 DTC set?
YES : Replace A/C-ECU and then go to step 4.
NO : A poor connection, open circuit or other intermittent malfunction is present in the lines between the A/C-ECU and the multi-center display.
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 multi-center display and then go to step 5.
NO : A poor connection, open circuit or other intermittent malfunction is present in the lines between the A/C-ECU and the multi-center display.
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 : Go to Step 1.
NO : The procedure is complete. (If no malfunctions are found in all steps, an intermittent malfunction is suspected).