DTC C120C-79: Linear Solenoid Power Supply System Malfunction [10/2014 - 05/2019]: Procedure

1. Disconnect the I55 4WD ECU assembly connector.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a	Front view of wire harness connector (to 4WD ECU Assembly)

2. Turn the engine switch on (IG).
3. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Switch Condition	Specified Condition
   I55-3 (IG1) -Body ground	Engine switch on (IG)	11 to 14 V

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  2

1. Turn the engine switch off.
2. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   I55-4 (GND) -Body ground	Always	Below 1 Ω

   Result

   Proceed to
   OK
   NG

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a	Front view of wire harness connector (to 4WD ECU Assembly)

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  3

1. Reconnect the I55 4WD ECU assembly connector.
2. Clear the DTCs.

   Refer to DTC CHECK / CLEAR [10/2014 - 05/2019]

   Chassis > Four Wheel Drive > Clear DTCs 

3. Turn the engine switch on (IG).
4. Check that no DTCs other than DTC C120C/79 have been output.

   Refer to DTC CHECK / CLEAR [10/2014 - 05/2019]

   Chassis > Four Wheel Drive > Trouble Codes 

   Result

   Proceed to
   DTCs other than C120C/79 are not output
   DTCs other than C120C/79 are output

Result: 

DTCs other than C120C/79 are not output 

REPLACE 4WD ECU ASSEMBLY. Refer to  REMOVAL [10/2014 - 05/2019] 

Result: 

DTCs other than C120C/79 are output 

REPAIR CIRCUIT INDICATED BY OUTPUT CODE. Refer to  DIAGNOSTIC TROUBLE CODE CHART [10/2014 - 05/2019]