ETACS
DTC U0164: A/C-ECU Or Heater Control Unit CAN TimeoutCAUTION:
- If DTC U0164 is set to the ETACS-ECU, always diagnose the CAN bus line.
- Before replacing the ECU, ensure that the communication circuit is normal.
TROUBLE JUDGMENT
If the signal from A/C-ECU [vehicles with automatic A/C] or heater control unit [vehicles without automatic A/C] cannot be received, the ETACS-ECU sets DTC U0164.
JUDGMENT CRITERIA
After the following statuses continue to be true for 5 seconds, if the communication with the A/C-ECU or heater control unit cannot be established for 0.6 second or more, the ETACS-ECU determines that a problem has occurred.
- No abnormality is present to the network.
- Ignition switch is in the ON position.
- No abnormality is present to the power supply fuse (IOD fuse), or the odometer value is at 80.5 km (50.0 miles) or more.
- ETACS-ECU system voltage is at 10 - 16 volts.
TROUBLESHOOTING HINTS
- The A/C-ECU or heater control unit may be defective.
- The ETACS-ECU may be defective.
- The CAN bus may be defective.
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.
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 the Scan Tool (M.U.T.-III)." How to Connect the Scan Tool (M.U.T.-III)
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-ECU or heater control unit diagnostic trouble code.
Check if DTC is set to the A/C-ECU or heater control unit.
Q: Is the DTC set?
YES : Troubleshoot the A/C-ECU or heater control unit (Refer to A/C Diagnosis). Diagnostic Trouble Code Descriptions
NO : Go to Step 3.
STEP 3. Using scan tool MB991958, read the combination meter diagnostic trouble code.
Check if the DTC U0164 is set to the combination meter.
Q: Is the DTC set?
YES : Go to Step 4.
NO : Go to Step 5.
STEP 4. Recheck for diagnostic trouble code.
Check again if the DTC is set to the ETACS-ECU
1. Erase the DTC.
2. Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
3. Check if DTC is set.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the DTC set?
YES : Replace the A/C-ECU or heater control unit.
NO : The trouble can be an intermittent malfunction such as a poor connection or open circuit in the CAN bus lines between the A/C-ECU or heater control unit and the ETACS-ECU.
STEP 5. Recheck for diagnostic trouble code.
Check again if the DTC is set to the ETACS-ECU
1. Erase the DTC.
2. Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
3. Check if DTC is set.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the DTC set?
YES : Replace the ETACS-ECU.
NO : The trouble can be an intermittent malfunction such as a poor connection or open circuit in the CAN bus lines between the A/C-ECU or heater control unit and the ETACS-ECU.