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DTC U0164: A/C/Heater control unit CAN timeout
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- If DTC U0164 is set, be sure to diagnose the CAN bus line.
- When replacing the ECU, always check that the communication circuit is normal.
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DIAGNOSTIC FUNCTION
If the signal from A/C-ECU <vehicles with A/C> or heater control unit <vehicles without A/C> cannot be received, the combination meter sets DTC U0164.
JUDGMENT CRITERIA
With the ignition switch in the ON position, system voltage between 10-16 volts (data from ETACS-ECU), power supply fuse (IOD fuse) is OK, or odometer value is 80.5 km (50 miles) or more, and the communication with A/C-ECU <vehicles with A/C> or heater control unit <vehicles without A/C> cannot be established for 2,500 ms or more, the combination meter determines that a problem has occurred.
TROUBLESHOOTING HINTS
- The CAN bus line may be defective.
- The A/C-ECU <vehicles with A/C> or heater control unit <vehicles without A/C> may be defective.
- The combination meter may be defective.
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Required Special Tools:
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: Vehicles 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)
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STEP 1. Using scan tool MB991958, diagnose the CAN bus line.
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(1)
| 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.
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Connect scan tool MB991958. Refer to "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?
 Go to Step 2.
 Repair the CAN bus line (Refer to GROUP 54C, Diagnosis ).
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STEP 2. Using scan tool MB991958, read the A/C/Heater control unit diagnostic trouble code.
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Check if DTC is set to the A/C/Heater control unit.
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Troubleshoot the A/C/Heater control unit (Refer to GROUP 55A, Manual A/C Diagnosis or GROUP 55B, Auto A/C Diagnosis ).
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Go to Step 3.
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STEP 3. Using scan tool MB991958, read the ETACS diagnostic trouble code.
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Check if the DTC U0164 is set to the ETACS-ECU.
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Go to Step 4.
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Go to Step 5.
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STEP 4. Recheck for diagnostic trouble code.
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Check again if the DTC is set to the combination meter.
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(2)Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
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(4)Turn the ignition switch to the "LOCK" (OFF) position.
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Replace the A/C-ECU <vehicles with A/C> or heater control unit <vehicles without A/C>.
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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 <vehicles with A/C> or heater control unit <vehicles without A/C> and the combination meter (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).
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STEP 5. Recheck for diagnostic trouble code.
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Check again if the DTC is set to the combination meter.
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(2)Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
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(4)Turn the ignition switch to the "LOCK" (OFF) position.
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Replace the combination meter.
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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 <vehicles with A/C> or heater control unit <vehicles without A/C> and the combination meter (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).
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)