ECU Power Source Circuit [09/2015 - ]: Procedure

1. Check the battery voltage.

   Standard voltage

   11 to 14 V

Result: 

NG 

CHECK OR REPLACE CHARGING SYSTEM OR BATTERY 

Refer to ON-VEHICLE INSPECTION [09/2015 - ] )

Result: 

OK 

See step  2

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. Turn the engine switch off.
2. Disconnect the A27 and A28 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
   A27-21 (+B) - Body ground	Always	11 to 14 V
   A28-4 (IG) - Body ground	IEngine switch on (IG)	11 to 14 V

   TEXT IN ILLUSTRATION
   
   

   * a	Front view of wire harness connector (to 4 Wheel Drive Control ECU)

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
   A28-10 (GND) - Body ground	Always	Below 1 Ω

   TEXT IN ILLUSTRATION
   
   

   * a	Front view of wire harness connector (to 4 Wheel Drive Control ECU)

Result: 

OK 

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE 

Refer to PROBLEM SYMPTOMS TABLE [09/2015 - ] )

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR (GND CIRCUIT)