Combination Meter Assembly
DTC U1110: A/C-ECU time-out.CAUTION:
- If DTC U1110 is set in the multi-center display unit (middle grade type), always diagnose the CAN main bus line.
- Whenever the multi-center display unit (middle grade type) is replaced, ensure that the communication circuit is normal.
NOTE: When the DTC relating to the CAN communication error are set, make sure of the vehicle equipment. When the vehicle is not equipped with the system the multi-center display unit (middle grade type) communicates to, the DTC is always set. This is not abnormal.
TROUBLE JUDGMENT
The multi-center display unit (middle grade type) receives air conditioning system-related signal from the A/C-ECU. If an air conditioning control system- related signal cannot be received, DTC U1110 will be set.
TECHNICAL DESCRIPTION (COMMENT)
Current trouble
- Connector(s) or wiring harness in the CAN bus lines between the A/C-ECU and the multi-center display unit (middle grade type), the power supply system to the A/C-ECU, the A/C-ECU, or the multi-center display unit (middle grade type) may be defective.
Past trouble
- If DTC U1110 is 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 wiring harness or connectors may have loose, corroded, or damaged terminals, or terminals pushed back in the connector
- The A/C-ECU may be defective
- The multi-center display unit (middle grade type) 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 the A/C diagnostic trouble code.
Check if an A/C-ECU DTC is set.
1. Turn the ignition switch to the "ON" position.
2. Check whether A/C system-related DTC is set.
3. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the DTC set?
YES : Diagnose the air conditioning system (Refer to Diagnosis [manual A/C] Diagnostic Trouble Code Descriptions or Diagnosis [automatic A/C]). Diagnostic Trouble Code Descriptions
NO : Go to Step 3.
STEP 3. Using scan tool MB991958, read the diagnostic trouble code.
Check if a DTC, which relates to CAN communication-linked systems below, is set.
Powertrain control module
- DTC U1110: A/C-ECU time-out
ETACS-ECU
- DTC U1110: A/C-ECU time-out
Q: Is the DTC set?
YES : Go to Step 4.
NO : Go to Step 5.
STEP 4. Using scan tool MB991958, read the for any diagnostic trouble code.
Check if a DTC, which relates to CAN communication-linked systems below, is set.
- Combination meter
A/C-related time-out DTC
1. Turn the ignition switch to the "ON" position.
2. Check for a DTC related to the relevant system.
3. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the DTC set?
YES : Go to Step 5.
NO : Go to Step 6.
STEP 5. Recheck for diagnostic trouble code.
Check again if the DTC is set.
1. Turn the ignition switch to the "ON" position.
2. Check if the DTC is set.
3. Turn the ignition switch to the "LOCK" (OFF) position.
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 CAN bus lines between the A/C-ECU and the multi-center display unit (middle grade type).
STEP 6. Recheck for diagnostic trouble code.
Check again if the DTC is set.
1. Turn the ignition switch to the "ON" position.
2. Check if the DTC is set.
3. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the DTC set?
YES : Go to Step 1.
NO : The procedure is complete.