TIRE PRESSURE MONITORING SYSTEM (TPMS) DIAGNOSIS
TSB Revision
WHEEL AND TIRE
31-22
DTC C1901: Vehicle speed signal
If 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 P.54C-12).
.
DTC SET CONDITION
ETACS-ECU <Vehicles without Keyless Operation
System> or KOS&OSS-ECU <Vehicles with Keyless
Operation System> receives the wheel speed infor
-
mation 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 infor
-
mation that the wheel is not currently rotated from
ASC-ECU, if the TPMS transmitter sends the infor
-
mation 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 may be defective.
Malfunction of TPMS transmitter
Malfunction of ETACS-ECU <Vehicles without
Keyless Operation System>
Malfunction of KOS&OSS-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.
Q: Is the check result normal?
YES : Go to Step 2.
NO : Repair the CAN bus lines (Refer to GROUP 54C
CAN Bus Diagnostics Table
P.54C-11). 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 (engine starting switch) from the
"LOCK" (OFF) to ON position.
(2) Check if the DTC is set.
(3) Turn the ignition switch (engine starting switch) to the
"LOCK" (OFF) position.
Q: Is the DTC set?
YES : Go to Step 3.
NO : The procedure is complete.
STEP 3. Using scan tool other system DTC
Check if the DTC is set in the ASC-ECU.
Q: Is the DTC set?
YES : Carry out the troubleshooting for ASC-ECU (Refer to
GROUP 35C
Troubleshooting P.35C-16). Then go
to Step 5.
NO : Go to Step 4.
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