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DTC No.C2100: Power supply low voltage
 
 
caution
  • If there is any problem in the CAN bus lines, an incorrect DTC may be set. Prior to this diagnosis, diagnose the CAN bus lines.
  • Whenever the ECU is replaced, ensure that the communication circuit is normal.
  • When the ETACS-ECU of vehicles without KOS is replaced, the encrypted code of the ignition key needs to be registered to the ETACS-ECU. (If the encrypted code is not registered, the engine cannot be started. Register the encrypted code as described in GROUP 54A, Immobilizer System - How to Register Key ID .)
 
 
OPERATION
AWD-ECU power supply is provided from the battery via ETACS-ECU.
 
 
DTC SET CONDITIONS
When the conditions below are satisfied at the system start-up, the drive train will be switched from AWD to FWD gradually and the AWD operation indicator and the LOCK indicator will flash alternately. Then diagnostic trouble code No. C2100 will be set.
  • Voltage between the battery and ETACS-ECU: Less than 9 V
  • IG1 Voltage: Less than 9 V
 
 
TROUBLESHOOTING HINTS
  • Battery failure
  • Malfunction of charging system
  • Malfunction of ETACS-ECU (power supply circuit system)
  • Damaged harness wires and connectors
  • Malfunction of electronic control coupling solenoid
  • Malfunction of AWD-ECU
 
 
DIAGNOSIS
Required Special Tools:
  • MB991223: Harness Set
  • MB992006: Extra Fine Probe
STEP 1. Scan tool (M.U.T.-III) other system DTC.
(1)
cautionTo prevent damage to scan tool (M.U.T.-III), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-III).
Connect scan tool (M.U.T.-III). Refer to "How to connect the Scan Tool (M.U.T.-III) ."
(2) Turn the ignition switch to the "ON" position.
(3) Check the ETACS DTC (Refer to GROUP 54A - Troubleshooting ).
Is the DTC set?
Perform the relevant troubleshooting.
Go to Step 2.
 
STEP 2. Check the battery.
Refer to GROUP 54A - Battery Test .
Is the check result normal?
Go to Step 4.
Charge or replace the battery. Then go to Step 3.
 
STEP 3. Check the charging system.
Refer to GROUP 16 - Charging System .
Is the check result normal?
Go to Step 4.
Repair or replace the charging system component(s).
 
STEP 4. Voltage measurement at AWD-ECU connector
Disconnect the connector, and measure the voltage between terminal 4WDF 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 6.
Repair the defective connector or the wiring harness. Then go to Step 5.
 
STEP 5. Scan tool (M.U.T.-III) data list.
Check the following data list (Refer to ).
  • Item No.31: Battery voltage (CAN input)
Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).
Replace the ETACS-ECU. Then go to Step 10.
 
STEP 6. Measure the resistance at the AWD-ECU connector.
(1) Disconnect the connector, and measure at the wiring harness side.
(2) Resistance between AWD-ECU connector terminal GND1 and body ground.
OK: The resistance should be 2 ohms or less
Is the check result normal?
Go to Step 8.
Go to Step 7.
 
STEP 7. Check the wiring harness between AWD-ECU connector terminal GND1 and body ground.
Check the ground line for open circuit.
Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).
Repair the defective connector or the wiring harness. Then go to Step 12.
 
STEP 8. Measure the resistance at the AWD-ECU connector.
(1) Disconnect the connector, and measure at the wiring harness side.
(2) Resistance between AWD-ECU connector terminal SOL+, SOL- and body ground
OK: No continuity
Is the check result normal?
Go to Step 10.
Go to Step 9.
 
STEP 9. Check the wiring harness between electronic control coupling solenoid connector and AWD-ECU connector terminal SOL+, SOL-.
Check the power supply, ground line for short circuit.
Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).
Repair the defective connector or the wiring harness. Then go to Step 12.
 
STEP 10. Check of the electronic control coupling solenoid
Refer to .
Is the check result normal?
Go to Step 11.
Replace the electronic control coupling (Refer to ). Then go to Step 12.
 
STEP 11. Scan tool (M.U.T.-III) data list.
Check the following data list (Refer to ).
  • Item No.31: Battery voltage (CAN input)
Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).
Replace the AWD-ECU (Refer to ). Then go to Step 12.
 
STEP 12. Check whether the DTC is set again.
Is DTC No.C2100 set?
Return to Step 1.
This diagnosis is complete.