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DTC C1901: Vehicle Speed Information Abnormality
 
 
cautionIf there is any problem in the CAN bus lines, an incorrect diagnostic trouble code may be set. Prior to this diagnosis, diagnose the CAN bus lines (Refer to GROUP 54C, Trouble code diagnosis ).
 
 
DTC SET CONDITION
KOS-ECU receives the wheel speed information from ASC-ECU via the CAN-bus line. Although KOS-ECU receives the information that the wheel is not currently rotated from ASC-ECU, if the TPMS transmitter sends the information that the wheel is rotated, this code is set.
 
 
 
TROUBLESHOOTING HINTS
The most likely causes for this DTC to set are:
  • Damaged wiring harness and connector
  • Malfunction of TPMS transmitter
  • Malfunction of KOS-ECU
  • Malfunction of ASC-ECU
  • Malfunction of ETACS-ECU
 
 
 
 
DIAGNOSIS
Required Special Tools:
  • MB991958: Scan Tool (M.U.T.-III Sub Assembly)
    • MB991824: Vehicle Communication Interface (V.C.I.)
    • MB991827: M.U.T.-III USB Cable
    • MB991910: M.U.T.-III Main Harness A
STEP 1. M.U.T.-III CAN bus diagnostics
Use scan tool to diagnose the CAN bus lines.
Is the check result normal?
Go to Step 3.
Repair the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics table ). On completion, go to Step 2.
 
STEP 2. Diagnostic trouble code recheck after resetting CAN bus lines
(1) Turn the power supply mode of the engine switch to OFF.
(2) Turn the power supply mode of the engine switch to ON.
(3) Check if the DTC is set.
(4) Turn the power supply mode of the engine switch to OFF.
Is the DTC C1901 set?
Go to Step 3.
The procedure is complete.
 
STEP 3. Check for other diagnostic trouble code.
Check if the diagnostic trouble code is set from ASC-ECU (Refer to GROUP 35C,diagnostic trouble code chart ).
Is the check result normal?
Go to Step 4.
Carry out the troubleshooting for ASC-ECU (Refer to GROUP 35C,diagnostic trouble code chart ). Then go to Step 6.
 
STEP 4. Check for other diagnostic trouble code.
Check if the diagnostic trouble code is set from ETACS-ECU (Refer to GROUP 54A, ETACS - diagnostic trouble code chart ).
Is the check result normal?
Go to Step 5.
Troubleshoot the set DTC (Refer to GROUP 54A, ETACS - diagnostic trouble code chart ). Then go to Step 6.
 
STEP 5. Check the TPMS transmitter acceleration.
Check the acceleration value of each TPMS transmitter by the air pressure of data list (Refer to ).
OK:
  • Acceleration value: 5G or less
Is the check result OK?
Replace the KOS-ECU and register ID codes (Refer to ). Then go to Step 6.
Replace the TPMS transmitter and register ID codes (Refer to ). Then go to Step 6.
 
STEP 6. Recheck for diagnostic trouble code.
(1) Turn the power supply mode of the engine switch to OFF.
(2) Turn the power supply mode of the engine switch to ON.
(3) Check if the DTC is set.
(4) Turn the power supply mode of the engine switch to OFF.
Is the DTC C1901 set?
Start over at Step 1.
The procedure is complete.