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DTC U15A4 VIN information lost
 
 
caution
  • If DTC U15A4 is set in the occupant classification-ECU, diagnose the CAN main bus line.
  • Whenever the ECU is replaced, ensure that the communication circuit is normal.
 
 
TROUBLE JUDGMENT
When the occupant classification-ECU cannot receive any signal (motor driving and selector lever position) from the engine control module for 500 milliseconds or more, it sets diagnostic trouble code No. U15A4 (motor driving).
 
 
PROBABLE CAUSES
  • Malfunction of the engine control module
  • Malfunction of the occupant classification-ECU
  • Malfunction of the CAN bus
 
 
DIAGNOSIS
STEP 1. Using scan tool MB991958, diagnose the CAN bus line.
cautionTo 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 ."
(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 again if the DTC is set in the engine control module.
Is the DTC set?
Troubleshoot the engine control module (Refer to GROUP 13A - DTC Chart <2.0 L ENGINE>, GROUP 13C - DTC Chart <2.4 L ENGINE>).
Go to Step 3.
 
STEP 3. Check whether the diagnostic trouble code is set again.
Check again if the DTC is set in the occupant classification-ECU.
(1) Erase the DTC.
(2) Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
(3) Check if DTC is set.
Is the DTC set?
Replace the engine control module and register the ID codes (Refer to GROUP 42C, On-vehicle Service - ID Codes Registration Procedure ). Then, carry out the CAN bus diagnostics. Then go to Step 4.
A poor connection, open circuit or other intermittent malfunction is present in the CAN bus lines between the engine control module and the occupant classification-ECU (Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).
 
STEP 4. Check whether the diagnostic trouble code is set again.
Check again if the DTC is set in the occupant classification-ECU.
(1) Erase the diagnostic trouble code.
(2) Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
(3) On completion, check that the diagnostic trouble code is set again.
Is the DTC set?
Replace the front seat cushion cover and pad assembly (Refer to GROUP 52A, Front Seat Assembly ). Then, carry out the CAN bus diagnostics. Then go to Step 5.
A poor connection, open circuit or other intermittent malfunction is present in the CAN bus lines between the engine control module and the occupant classification-ECU (Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).
 
STEP 5. Check whether the diagnostic trouble code is set again.
Recheck if the DTC is set in the occupant classification-ECU.
(1) Erase the DTC.
(2) Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
(3) On completion, check that the DTC is set again.
Is the DTC set?
Return to Step 1.
The procedure is complete.