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DTC C1750: Voltage out of Range
 
 
 
 
OPERATION
ACC-ECU power supply is provided from the 12V starter battery via ETACS-ECU.
 
 
DIAGNOSTIC TROUBLE CODE SET CONDITIONS
This DTC is set when the abnormality below is detected:
  • Voltage between the 12V starter battery and ETACS-ECU: Less than 9.0 V
  • Voltage between the 12V starter battery and ETACS-ECU: More than 16.0 V
 
 
PROBABLE CAUSES
  • 12V starter battery failure
  • Loose 12V starter battery terminal
  • Malfunction of charging system
  • Malfunction of ETACS-ECU (power supply circuit system)
  • Damaged harness wires and connectors
  • Malfunction of ACC-ECU
 
 
DIAGNOSIS
Required Special Tools:
  • MB991223: Harness Set
  • MB992006: Extra Fine Probe
STEP 1. Check the 12V starter battery.
Refer to GROUP 54A - 12V Starter Battery Test .
Is the check result normal?
Go to Step 2.
Charge or replace the 12V starter battery.
 
STEP 2. Voltage measurement at ACC-ECU connector
(1) Check the connector
(2) Disconnect the connector.
(3) Turn the power supply mode of electric motor switch ON.
(4) Measure the voltage between 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 3.
Repair the wiring harness in IG line between ACC-ECU connector and IG1 relay connector.
 
STEP 3. Check of damage circuit in GND line between ACC-ECU connector and body ground.
Is the check result normal?
Go to Step 4.
Repair the connector(s) or wiring harness.
 
STEP 4. Using scan tool (M.U.T.-IIISE), check the data list.
(1)
cautionTo prevent damage to scan tool (M.U.T.-IIISE), always turn off the power supply mode of the electric motor switch 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 on the power supply mode of the electric motor switch.
(3) Check the following data list (Refer to ).
  • Item No.01: ECU power supply voltage
(4) Turn off the power supply mode of the electric motor switch.
Is the check result normal?
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 ).
Replace the ACC-ECU (Refer to ).