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DTC U1000: OSS-ECU CAN timeout
 
 
caution
  • If DTC U1000 is set, be sure to diagnose the CAN bus line.
  • When replacing the ECU, always check that the communication circuit is normal.
 
 
DIAGNOSTIC FUNCTION
If the signal from OSS-ECU cannot be received, the combination meter sets DTC U1000.
 
 
JUDGMENT CRITERIA
With the ignition switch in the ON position, system voltage between 10 - 16 V (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 OSS-ECU cannot be established for 2,500 ms or more, the combination meter determines that a problem has occurred.
 
 
TROUBLESHOOTING HINTS
  • Malfunction of CAN bus line may be defective.
  • Malfunction of the OSS-ECU may be defective.
  • Malfunction of combination meter 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 OSS-ECU diagnostic trouble code.
Check again if the DTC is set to the OSS-ECU.
Is the DTC set?
Troubleshoot the OSS-ECU (Refer to GROUP 42B, Troubleshooting ).
Go to Step 3.
 
STEP 3. Using scan tool MB991958, read the diagnostic trouble code.
Check if the DTC U1000 is set to 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 to 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 OSS-ECU.
The trouble can be an intermittent malfunction such as a poor connection or open circuit in the CAN bus lines between the OSS-ECU 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 to 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 OSS-ECU and the combination meter (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).