IG Signal Circuit: Procedure

1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the Techstream on.
4. Enter the following menus: Body Electrical / Main Body / Data List.
5. Read the display on the Techstream.
   MAIN BODY (MAIN BODY ECU)
   
   

   Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
   IG SW	Ignition switch IG signal/ON or OFF	ON: Ignition switch ON OFF: Ignition switch off	-

   OK

   Normal conditions listed above are displayed.

NG → See step   2 

OK → See step   4 

1. Remove the ECU-IG No. 1 fuse from the instrument panel junction block.
2. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   ECU-IG No. 1 fuse	Always	Below 1 Ω

NG → REPLACE FUSE 

OK: Go to next step 

1. Measure the voltage between the loading slot of the fuse and body ground.
   Fig 1: Identifying ECU-IG NO. 1 Fuse Terminal

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Standard Voltage

   Tester Connection	Switch Condition	Specified Condition
   ECU-IG No. 1 fuse terminal - Body ground	Ignition switch off	Below 1 V
   	Ignition switch ON	11 to 14 V

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK → REPLACE MAIN BODY ECU (INSTRUMENT PANEL JUNCTION BLOCK)