Code No. C1901:
Vehicle speed signal
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If there is any
problem in the CAN bus lines, an incorrect diagnosis code may be set. Prior to this diagnosis,
diagnose the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics Table ).
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DIAGNOSTIC FUNCTION
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 set.
PROBABLE CAUSES
The most likely causes for this diagnosis code to be set is:
- 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
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STEP 1. M.U.T.-III CAN bus diagnosis
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Use the M.U.T.-III to diagnose the CAN bus lines.
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Q.
Is the check result normal?
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Go to Step 2.
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Repair the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics Table ).
On completion, go to Step 2.
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STEP 2. Diagnosis code recheck after resetting CAN bus lines
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Recheck if diagnosis code No. C1901 is set.
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(1)Turn the ignition switch from the "LOCK" (OFF) to "ON" position.
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(2)Check if the diagnosis code is set.
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(3)Turn the ignition switch to the "LOCK" (OFF) position.
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Q.
Is the diagnosis code set?
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Go to Step 3.
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The procedure is complete.
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STEP 3. Using M.U.T.-III other system diagnosis code
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Check if the diagnosis code is set in the ASC-ECU.
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Q.
Is the diagnosis code set?
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Carry out the troubleshooting for ASC-ECU (Refer to GROUP 35C - Troubleshooting ).
Then go to Step 5.
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Go to Step 4.
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STEP 4. Check the TPMS transmitter acceleration.
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Check the acceleration value sent by each TPMS transmitter by performing the transmitter
check using the M.U.T.-III (Refer to ) when the vehicle
is stationary.
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- Item 31: Acceleration tyre1
- Item 32: Acceleration tyre2
- Item 33: Acceleration tyre3
- Item 34: Acceleration tyre4
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OK:
Acceleration value: 5G or less
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Q.
Is the check result normal?
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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.
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Replace the TPMS transmitter (Refer to ), and
register ID codes (Refer to ). Then go to Step 5.
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STEP 5. Check whether the diagnosis code is set again.
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Recheck if the diagnosis code is set.
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(1)Turn the ignition switch from the "LOCK" (OFF) to "ON" position.
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(2)Check if the diagnosis code is set.
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(3)Turn the ignition switch to the "LOCK" (OFF) position.
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Q.
Is diagnosis code No. C1901 set?
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Start over at Step 1.
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The procedure is complete.
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