Code No. C1791:
Vehicle speed signal (invalid)
caution |
If a diagnosis code is set,
be sure to diagnose the CAN bus line.
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DIAGNOSTIC FUNCTION
If the laser radar receives an invalid value of the vehicle speed signal from the ASC-ECU,
diagnosis code No. C1791 is set. Diagnosis code No. C1777 may be set simultaneously.
CHECK CONDITION
When all the following conditions are satisfied.
- After the ignition switch is turned ON, two or more seconds passed.
- After the engine has started.
PROBABLE CAUSES
- ASC system error (all wheel speed sensors)
- Malfunction of the CAN bus line
- Malfunction of the laser radar
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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 line (Refer to GROUP 54C - Troubleshooting ).
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STEP 2. M.U.T.-III other system diagnosis code check.
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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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Perform the ASC troubleshooting (Refer to GROUP 35C - Troubleshooting ).
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Go to Step 3.
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STEP 3. Check whether the diagnosis code is set again.
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Check again if the diagnosis code is set in the laser radar.
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(1)Erase the set diagnosis code.
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(2)Turn the ignition switch to the "LOCK" (OFF) position.
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(4)Check if the diagnosis code is set.
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Q.
Is the diagnosis code set?
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Replace the laser radar (Refer to ).
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The trouble can be an intermittent malfunction (Refer to GROUP 00 - How
to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent
Malfunction).
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