Keyless Operation System (KOS)
DTC B1731: Engine Control Module communication timeoutCAUTION:
- When the DTC B1731 is set, be sure to diagnose the CAN bus line.
- When replacing the ECU, always check that the communication circuit is normal.
DTC SET CONDITION
KOS-ECU checks that the Engine Control Module data has been received via the CAN bus lines, and if not, sets the DTC No. B1731.
TECHNICAL DESCRIPTION (COMMENT)
If no data [ETACS transmits engine random number data to KOS-ECU via the CAN bus lines] is received from the Engine Control Module via the CAN bus lines when the ignition switch is turned to ON position, it is judged as abnormal.
TROUBLESHOOTING HINTS
- Malfunction of CAN bus line
- Malfunction of KOS-ECU
- Malfunction of engine control module
DIAGNOSIS
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)
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 to the data link connector.
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 Engine Control Module diagnostic trouble code
Check again if the DTC is set to the engine control module.
Q: Is the DTC set?
YES: Troubleshoot the MFI system (Refer to Diagnostic trouble code chart [2.0L Engine Non-turbo] Diagnostic Trouble Code Descriptions, Diagnostic trouble code chart [2.0L Engine Turbo] Diagnostic Trouble Code Descriptions or Diagnostic trouble code chart [2.4L Engine]). Diagnostic Trouble Code Descriptions
NO: Go to Step 3.
STEP 3. Recheck for diagnostic trouble code.
Check again if the DTC is set to the KOS-ECU.
1. Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
2. Check if DTC is set.
3. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the DTC set?
YES: Replace KOS-ECU and register the ID codes. After registering the ID codes, go to Step 4.
NO: The trouble can be an intermittent malfunction.
STEP 4. Recheck for diagnostic trouble code.
Check again if the DTC is set to the KOS-ECU.
1. Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
2. Check if DTC is set.
3. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the DTC set?
YES: Replace the engine control module and record the VIN. (Refer to How To Perform Vehicle Identification Number (VIN) Writing.)
NO: The procedure is complete.