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DTC C1901: Vehicle speed signal
 
 
cautionIf there is any problem in the CAN bus lines, an incorrect DTC may be stored. 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-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-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 stored.
 
 
TROUBLESHOOTING HINTS
The most likely causes for this DTC to be stored are:
  • Damaged wiring harness and connector
  • Malfunction of TPMS transmitter
  • Malfunction of ETACS-ECU <Vehicles without Keyless Operation System>
  • Malfunction of KOS-ECU <Vehicles with Keyless Operation System>
  • Malfunction of ASC-ECU
 
 
DIAGNOSIS
STEP 1. Using scan tool MB991958, 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 stored.
(1) Turn the ignition switch (engine starting switch) from the "LOCK" (OFF) to "ON" position.
(2) Check if the DTC is stored.
(3) Turn the ignition switch (engine starting switch) to the "LOCK" (OFF) position.
Is the DTC stored?
Go to Step 3.
The procedure is complete.
 
STEP 3. Using scan tool other system DTC
Check if the DTC is stored in the ASC-ECU.
Is the DTC stored?
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 .) or KOS-ECU <Vehicles with Keyless Operation System> (Refer to GROUP 42B, KOS-ECU .), and register ID codes (Refer to .). Then go to Step 5.
Replace the TPMS transmitter (Refer to <Vehicles with steel type wheels> or <Vehicles with aluminum type wheels>.), and register ID codes (Refer to .). Then go to Step 5.
 
STEP 5. Check whether the DTC is stored again.
Recheck if the DTC is stored.
(1) Turn the ignition switch (engine starting switch) from the "LOCK" (OFF) to "ON" position.
(2) Check if the DTC is stored.
(3) Turn the ignition switch (engine starting switch) to the "LOCK" (OFF) position.
Is DTC C1901 stored?
Start over at Step 1.
The procedure is complete.