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DTC C1901: Vehicle speed signal
 
 
cautionIf there is any problem in the CAN bus lines, an incorrect DTC may be set. Prior to this diagnosis, diagnose the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics Table ).
 
 
DTC SET CONDITION
ETACS-ECU <Vehicles without Keyless Operation System> or KOS&OSS-ECU <Vehicles with Keyless Operation System> receives the wheel speed information from ASC-ECU via the CAN-bus line. Although ETACS-ECU <Vehicles without Keyless Operation System> or KOS&OSS-ECU <Vehicles with Keyless Operation System> 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 be set are:
  • The CAN bus line may be faulty.
  • The TPMS transmitter may be faulty.
  • The ETACS-ECU may be faulty. <Vehicles without Keyless Operation System>
  • The KOS&OSS-ECU may be faulty. <Vehicles with Keyless Operation System>
  • The ASC-ECU may be faulty.
 
 
DIAGNOSIS
STEP 1. Using scan tool (M.U.T.-III), diagnose the CAN bus lines.
Use scan tool to diagnose the CAN bus lines.
Is the check result normal?
Go to Step 2.
Repair the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics Table ). On completion, go to Step 2.
 
STEP 2. DTC recheck after resetting CAN bus lines.
Recheck if DTC C1901 is set.
(1) Turn the ignition switch from the "LOCK" (OFF) to ON position.
(2) Check if the DTC is set.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Is the DTC set?
Go to Step 3.
The procedure is complete.
 
STEP 3. Using scan tool other system DTC.
Check if the DTC is set in the ASC-ECU.
Is the DTC set?
Carry out the troubleshooting for ASC-ECU (Refer to GROUP 35C - Troubleshooting ). Then go to Step 5.
Go to Step 4.
 
STEP 4. Check the TPMS transmitter acceleration.
Check the acceleration value sent by each TPMS transmitter by performing the transmitter check using the scan tool (Refer to ), when the vehicle is stationary.
  • Item 31: Acceleration, Tire1
  • Item 32: Acceleration, Tire2
  • Item 33: Acceleration, Tire3
  • Item 34: Acceleration, Tire4
OK:
  • Acceleration value: 5G or less
Is the check result normal?
Replace the ETACS-ECU <Vehicles without Keyless Operation System> (Refer to GROUP 54A - ETACS ) or KOS&OSS-ECU <Vehicles with Keyless Operation System> (Refer to GROUP 42B - KOS&OSS-ECU ), and register ID codes (Refer to ). Then go to Step 5.
Replace the TPMS transmitter (Refer to ), and register ID codes (Refer to ). Then go to Step 5.
 
STEP 5. Check whether the DTC is set again.
Recheck if the DTC is set.
(1) Turn the ignition switch from the "LOCK" (OFF) to "ON" position.
(2) Check if the DTC is set.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Is DTC C1901 set?
Start over at Step 1.
The procedure is complete.