Front Fog Light 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 / Active Test.
5. Check the operation.
   MAIN BODY:
   
   

   Tester Display	Test Part	Control Range	Diagnostic Note
   Front Fog Light Relay	Fog light relay	ON/OFF	-

   OK

   Front fog light relay operates. (Front fog lights come on.)

NG → See step   2 

OK → See step   7 

1. Remove the FR FOG 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
   FR FOG fuse	Always	Below 1 Ω

NG → REPLACE FUSE 

OK: Go to next step 

1. Remove the fog light relay from the instrument panel junction block.
   Fig 1: Measuring Resistance Of Fog Light Relay

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Measure the resistance according to the value(s) in the table below.

   Standard resistance

   Tester Connection	Condition	Specified Condition
   3 - 5	Voltage is not applied between terminals 1 and 2	10 kΩ or higher
   3 - 5	Apply the battery voltage between terminals 1 and 2	Below 1 Ω

NG → REPLACE FOG LIGHT RELAY 

OK: Go to next step 

1. Remove the fog light relay from the instrument panel junction block.
   Fig 2: Checking Harness And Connector (Battery - Front Fog Light Relay)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Measure the voltage according to the value(s) in the table below.

   Standard voltage

   Tester Connection	Condition	Specified Condition
   Fog light relay terminal 5 - Body ground	Always	11 to 14 V
   Fog light relay terminal 1 - Body ground	Light control switch OFF → TAIL	Below 1 V → 11 to 14 V

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Remove the fog light relay from the instrument panel junction block.
   Fig 3: Checking Harness And Connector (Front Fog Light Relay - Main Body ECU)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Disconnect the D8 main body ECU connector.
3. Measure the resistance according to the value(s) in the table below.

   Standard resistance

   Tester Connection	Condition	Specified Condition
   Fog light relay terminal 2 - D8-4 (FFGO)	Always	Below 1 Ω
   D8-4 (FFGO) - Body ground	Always	10 kΩ or higher

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Remove the main body ECU with its connectors still connected.
   Fig 4: Checking Main Body ECU (Instrument Panel Junction Block)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Measure the voltage according to the value(s) in the table below.

   Standard voltage

   Tester Connection	Switch Condition	Specified Condition
   D8-4 (FFGO) - Body ground	Light control switch in HEAD, front fog light switch OFF → ON	11 to 14 V → Below 1 V

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

OK → REPAIR OR REPLACE HARNESS OR CONNECTOR (FOG LIGHT RELAY - BODY GROUND)