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DTC U0100: Engine control module CAN timeout
 
 
caution
  • If DTC U0100 is set, be sure to diagnose the CAN bus line.
  • When replacing the ECU, always check that the communication circuit is normal.
 
 
DIAGNOSTIC FUNCTION
The combination meter sets DTC U0100 when it cannot receive "CHECK ENGINE" signals from the engine control module.
 
 
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 engine control module cannot be established for 600 ms or more, the combination meter determines that a problem has occurred.
 
 
PROBABLE CAUSES
  • The CAN bus line may be defective.
  • The combination meter may be defective.
  • The engine control module may be defective.
 
 
DIAGNOSIS
STEP 1. Using scan tool MB991958, diagnose the CAN bus line
(1)
cautionTo prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
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.
Is the CAN bus line found to be normal?
Go to Step 2.
Repair the CAN bus line (Refer to GROUP 54C, Diagnosis ).
 
STEP 2. Using scan tool MB991958, read the engine control module diagnostic trouble code.
Check if DTC is set in the engine control module.
Is the DTC set?
Troubleshoot the engine (Refer to GROUP 13A, Diagnosis <2.0L ENGINE> or GROUP 13C, Diagnosis <2.4L ENGINE>).
Go to Step 3.
 
STEP 3. Using scan tool MB991958, read the ETACS diagnostic trouble code.
Check if DTC U0100 is set in the ETACS-ECU.
Is the DTC set?
Go to Step 4.
Go to Step 5.
 
STEP 4. Recheck for diagnostic trouble code.
Check again if the DTC is set in the combination meter.
(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.
Is the DTC set?
Replace the engine control module.
The trouble can be an intermittent malfunction such as a poor connection or open circuit in the CAN bus lines between the engine control module and the combination meter (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).
 
STEP 5. Recheck for diagnostic trouble code.
Check again if the DTC is set in the combination meter.
(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.
Is the DTC set?
Replace the combination meter.
The trouble can be an intermittent malfunction such as a poor connection or open circuit in the CAN bus lines between the engine control module and the combination meter (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).