Wireless Control Module (WCM)
DTC C1901: Vehicle Speed Information AbnormalityCAUTION: If 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 Controller area network Trouble code diagnosis).
DTC SET CONDITION
WCM receives the wheel speed information from ABS-ECU via the CAN-bus line. Although WCM receives the information that the wheel is not currently rotated from ABS-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 WCM
- Malfunction of ABS-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.
Q: Is the check result normal?
YES : Go to Step 3.
NO : Repair the CAN bus lines (Refer to Controller area network CAN Bus Diagnostics table). On completion, go to Step 2.
STEP 2. Diagnostic trouble code recheck after resetting CAN bus lines
1. Turn the ignition switch to the "LOCK" (OFF) position.
2. Turn the ignition switch to the "ON" position.
3. Check if the DTC is set.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the DTC C1901 set?
YES : Go to Step 3.
NO : The procedure is complete.
STEP 3. Vehicle speed check by combination meter
During the vehicle driving, check that the correct vehicle speed is displayed on the combination meter.
Q: Is the check result normal?
YES : Go to Step 6.
NO : Go to Step 4.
STEP 4. Check for other diagnostic trouble code.
Check if the diagnostic trouble code is set from ABS-ECU
Q: Is the check result normal?
YES : Go to Step 5.
NO : Carry out the relevant troubleshooting.
STEP 5. Check for other diagnostic trouble code.
Check if the diagnostic trouble code is set from ETACS-ECU (Refer to Chassis electrical ETACS - diagnostic trouble code chart).
Q: Is the check result normal?
YES : Diagnose the combination meter. (Refer to Chassis electrical Combination meter - diagnostic trouble code chart) Go to Step 7.
NO : Carry out the relevant troubleshooting.(Refer to Chassis electrical, ETACS - diagnostic trouble code chart). Then go to Step 7.
STEP 6. Check the TPMS transmitter acceleration.
Check the acceleration value of each TPMS transmitter by the TPMS transmitter check function.
Q: Is the check result normal?
YES : Replace the WCM and register ID codes. Then go to Step 7.
NO : Replace the TPMS transmitter and register ID codes.Then go to Step 7.
STEP 7. Recheck for diagnostic trouble code.
1. Turn the ignition switch to the "LOCK" (OFF) position.
2. Turn the ignition switch to the "ON" position.
3. Check if the DTC is set.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the DTC C1901 set?
YES : Start over at Step 1.
NO : The procedure is complete.