ECU Power Source Circuit [08/2019 - ]: Procedure

1. Check the battery voltage.

   Standard voltage

   11 to 14 V

   Result

   Proceed to
   OK
   NG

Result: 

NG 

CHECK OR REPLACE CHARGING SYSTEM OR BATTERY 

Result: 

OK 

See step  2

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. Turn the engine switch off.
2. Disconnect the G41 and G42 4 wheel drive control ECU connectors.
3. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   G41-21 (+B) - Body ground	Always	11 to 14 V
   G42-4 (IG) - Body ground	Engine switch on (IG)	11 to 14 V

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR (+B AND IG CIRCUIT) 

Result: 

OK 

See step  3

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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
   G42-10 (GND) - Body ground	Always	Below 1 Ω

   Result

   Proceed to
   OK
   NG

Result: 

OK 

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to  PROBLEM SYMPTOMS TABLE [08/2019 - 08/2021]  , or refer to  PROBLEM SYMPTOMS TABLE [08/2021 - ] 

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR (GND CIRCUIT)