Code No. C1799: FCM control disabled (ENGINE)
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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 a signal indicating that the FCM-LS control is prohibited from the engine ECU, diagnosis code No. C1799 is set.
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
- Malfunction of the engine system (general illumination failure of the engine warning lamp)
- Malfunction of the combination meter system (ambient temperature sensor)
- Malfunction of the CAN bus line
- Malfunction of the laser radar
DIAGNOSIS PROCEDURE
STEP 1. M.U.T.-III CAN bus diagnosis
Use the M.U.T.-III to diagnose the CAN bus lines.
Q.
Is the check result normal?
Go to Step 2.
Repair the CAN bus line (Refer to GROUP 54C - Troubleshooting 
).
STEP 2. M.U.T.-III other system diagnosis code check
Check if a diagnosis code other than No. P1570 is set in the engine ECU.
Q.
Is a diagnosis code other than No. P1570 set?
Perform the MPI troubleshooting (Refer to GROUP 13A - Troubleshooting ).
Go to Step 3.
STEP 3. M.U.T.-III other system data list
Check the engine ECU service data (Refer to GROUP 13A - Troubleshooting ).
- Item No.181: Ambient temperature
Q.
Is the check result normal?
Go to Step 4.
Perform "Ambient temperature sensor does not work." of the combination meter.
STEP 4. Check whether the diagnosis code is set again.
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?
Replace the laser radar (Refer to ).
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/inspection Service Points - How to Cope with Intermittent Malfunction ).