Code No. C1750: FCM voltage out of range
DIAGNOSTIC FUNCTION
If the laser radar detects that the ECU power supply voltage is less than 8.5 V or more than 16.5 V, diagnosis code No. C1750 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 battery (battery life, insufficient charging, loosened terminal)
- Malfunction of the laser radar power supply line (power supply line disconnection, incorrect earthing, IG1 fuse fusing)
- Malfunction of the laser radar
DIAGNOSIS PROCEDURE
STEP 1. Battery check
Refer to Battery test 
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Q.
Is the battery normal?
Go to Step 2.
Charge or replace the battery.
STEP 2. Charging system check
Refer to GROUP 16 - Charging System.
Q.
Is the charging system normal?
Go to Step 3.
Repair or replace the components related to the charging system.
STEP 3. Resistance measurement at the laser radar connector (GND terminal)
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(1)Disconnect the connector, and measure the resistance at the wiring harness.
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(2)Measure the resistance between the laser radar connector (GND terminal) and body earth.
OK: Connect (2 Ω or lower)
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Q.
Is the check result normal?
Go to Step 5.
Go to Step 4.
STEP 4. Disconnection check of the GND line between the laser radar connector and body earth
Q.
Is the check result normal?
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/inspection Service Points - How to Cope with Intermittent Malfunction ).
Repair the connector(s) or wiring harness.
STEP 5. Voltage measurement at the laser radar connector (IG terminal)
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(1)Disconnect the connector, and measure the resistance at the wiring harness.
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(2)Turn the ignition switch to the "ON" position.
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(3)Check the voltage between the laser radar connector (IG terminal) and body earth.
OK: Battery voltage
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Q.
Is the check result normal?
Go to Step 7.
Go to Step 6.
STEP 6. Check of short to earth and disconnection in the IG line between the laser radar connector and ignition switch (IG1)
Q.
Is the check result normal?
Refer to the inspection procedure "Malfunction of the ignition switch power supply system" .
Repair the connector(s) or wiring harness.
STEP 7. 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 ).