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DTC C1750: Voltage Out of Range
 
 
cautionWhen the ACC/FCM-ECU is replaced, calibrate the radar (refer to ).
 
 
OPERATION
ACC/FCM-ECU power supply is provided from the battery via ETACS-ECU.
 
 
DIAGNOSTIC TROUBLE CODE SET CONDITIONS
Check Condition
  • More than 3 seconds have passed since the ignition switch was turned to "ON" position.
Judgment Criterion
  • Voltage between the battery and ACC/FCM-ECU: Less than 8.5 volts or more than 18.5 volts for 5 seconds.
noteA DTC is not set as a historic fault.
 
 
PROBABLE CAUSES
  • Battery failure
  • Loose battery terminal
  • Malfunction of charging system
  • Damaged harness wires and connectors
  • Malfunction of ACC/FCM-ECU
 
 
DIAGNOSIS
Required Special Tools:
  • MB991223: Harness Set
  • MB992006: Extra Fine Probe
STEP 1. Check the battery.
Refer to GROUP 54A - Battery, Battery Test .
Is the check result normal?
Go to Step 2.
Charge or replace the battery.
 
STEP 2. Check the charging system.
Refer to GROUP 16 - Charging System .
Is the check result normal?
Go to Step 3.
Repair or replace the charging system component(s).
 
STEP 3. Check of damage in GND line between ACC/FCM-ECU connector and body ground.
Is the check result normal?
Go to Step 4.
Repair the connector(s) or wiring harness.
 
STEP 4. Measure the terminal voltage at ACC/FCM-ECU connector.
(1) Check the connector
(2) Disconnect the connector.
(3) Turn the ignition switch to the "ON" position.
(4) Measure the terminal voltage between ACC/FCM-ECU connector terminal IG and body ground at the wiring harness side.
OK: The voltage should measure approximately 12 volts (battery positive voltage)
Is the check result normal?
Go to Step 5.
Repair the connector(s), or check and repair of short to ground, and open circuit in IG line between ACC/FCM-ECU connector and IG1 relay connector.
 
STEP 5. Using scan tool (M.U.T.-IIISE), check whether the DTC is set again.
(1)
cautionTo prevent damage to scan tool (M.U.T.-IIISE), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-IIISE).
Connect scan tool (M.U.T.-IIISE). Refer to "How to connect the Scan Tool (M.U.T.-IIISE) ."
(2) Turn the ignition switch to the "LOCK" (OFF) position to "ON" position.
(3) Press the ACC ON/OFF switch to turn the ACC system to ON.
(4) On completion, check that the DTC is set again.
Is DTC C1750 set?
Replace the ACC/FCM-ECU (Refer to ).
It can be assumed that this malfunction is intermittent (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points, How to Cope with Intermittent Malfunction ).