U1130
DTC U1130: Failure information on A/C-ECU.CAUTION:
- If DTC U1130 is set in the multi-center display unit (middle grade type), always diagnose the CAN main bus line.
- Before replacing the multi-center display unit (middle grade type), ensure that the power supply circuit and the ground circuit are normal.
TROUBLE JUDGMENT
The multi-center display unit (middle grade type) receives A/C-ECU-related signal from the A/C-ECU via the CAN bus lines. If there is any trouble in the communication data of the A/C-ECU, DTC U1130 will be set.
TECHNICAL DESCRIPTION (COMMENT)
Current trouble
- The wiring harness wire or connectors may have loose, corroded, or damage terminals, or terminals pushed back in the connector, the powertrain control module, the A/C-ECU or the multi-center display unit (middle grade type) may be defective.
Past trouble
- If DTC U1130 are stored as a past trouble, carry out diagnosis with particular emphasis on wiring and connector(s) in the CAN bus line between the A/C-ECU and the multi-center display unit (middle grade type), and the power supply system to the A/C-ECU.
NOTE: You cannot find a past trouble, by the M.U.T.-III CAN bus diagnostics even if there is a failure in CAN bus lines. In this case, check the CAN bus lines. You can narrow down the possible cause of the trouble by referring to the DTC, which is set regarding the CAN communication-linked ECUs. (Refer to CAN bus line Diagnostics Flow. Explanation About the Scan Tool (M.U.T.-III) CAN Bus Diagnostics
TROUBLESHOOTING HINTS
- The multi-center display unit (middle grade type) may be defective
- The A/C-ECU may be defective
DIAGNOSIS
Required Special Tools:
- MB991223: Harness Set
- MB992006: Extra Fine Probe
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: M.U.T.-III USB Cable
- MB991910: M.U.T.-III Main Harness A
STEP 1. Using scan tool MB991958, diagnose the CAN bus line.
CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
1. Connect scan tool MB991958. Refer to "How to connect SWS monitor." How to Connect SWS Monitor
2. Turn the ignition switch to the "ON" position.
3. Diagnose the CAN bus line.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the CAN bus line found to be normal?
YES : Go to Step 2.
NO : Repair the CAN bus line.
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 : Refer 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 and then go to Step 3.
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 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 unit (middle grade type).
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 unit (middle grade type) 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 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 : Go to Step 1.
NO : The procedure is complete. (If no malfunctions are found in all steps, an intermittent malfunction is suspected.