Wireless Control Module

DTC C1901: Vehicle Speed Information Abnormality

CAUTION: 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.

TPMS DTC SET CONDITION
WCM receives the wheel speed information from ABS-ECU or ASC-ECU via the CAN-bus line. If the WCM receives information from the ABS-ECU or ASC-ECU indicating the wheel is not currently rotating and the TPMS transmitter sends information indicating the wheel is currently rotating, 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 or ASC-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 MB991958, diagnose the CAN bus lines.

Q: Is the check result normal?

YES : Go to Step 3.

NO : Repair the CAN bus lines. On completion, go to Step 2.

STEP 2. Diagnostic trouble code recheck after resetting CAN bus lines.
1. Start the engine and drive the vehicle at 5 km/h or more.
2. Turn the ignition switch to the "LOCK" (OFF) position.
3. Turn the ignition switch to the "ON" position.
4. Check if the DTC is set.
5. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the diagnostic trouble code C1901 set?

YES : Go to Step 3.

NO : The procedure is complete.

STEP 3. Check for other diagnostic trouble code.
Check if the diagnostic trouble code is set from ABS-ECU or ASC-ECU.[Refer to ABS, diagnostic trouble code chart. (vehicles without ASC) or Refer to Active Skid Control System (ASC), diagnostic trouble code chart. (vehicles with ASC]

Q: Is the check result normal?

YES : Check the registered ID by the transmitter ID check function, and then check the acceleration value of each wheel by the transmitter check function. If the value exceeding 5 g is displayed, replace the relevant TPMS transmitter and register the ID code. If the value exceeding 5 g is not displayed for any TPMS transmitter, replace the WCM and register the ID codes. Then go to Step 4.

NO : Carry out the troubleshooting for ABS-ECU or ASC-ECU. [Refer to ABS, diagnostic trouble code chart. (vehicles without ASC) or Refer to Active Skid Control System (ASC), diagnostic trouble code chart. (vehicles with ASC)]. Then go to Step 4.

STEP 4. Recheck for diagnostic trouble code.
1. Start the engine and drive the vehicle at 5 km/h or more.
2. Turn the ignition switch to the "LOCK" (OFF) position.
3. Turn the ignition switch to the "ON" position.
4. Check if the DTC is set.
5. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the diagnostic trouble code C1901 set?

YES : Start over at Step 1.

NO : The procedure is complete.