Front Fog Light Circuit [10/2015 - 08/2019]: Procedure

1. Check the operation of the taillights.

   OK

   Taillights operate normally.

   Result

   Proceed to
   OK
   NG

Result: 

NG 

GO TO PROBLEM SYMPTOMS TABLE. Refer to  PROBLEM SYMPTOMS TABLE [10/2015 - 12/2017]  , or refer to  PROBLEM SYMPTOMS TABLE [12/2017 - 03/2018]  , or refer to  PROBLEM SYMPTOMS TABLE [03/2018 - 08/2019] 

Result: 

OK 

See step  2

1. Connect the Techstream to the DLC3.
2. Turn the power switch on (IG).
3. Turn the Techstream on.
4. Enter the following menus: Body Electrical / Main Body / Active Test.
5. Perform the Active Test according to the display on the Techstream.

   Body Electrical > Main Body > Active Test 

   Tester Display	Measurement Item	Control Range	Diagnostic Note
   Front Fog Light Relay	Front fog light relay	ON/OFF	Light control switch in tail position

   Body Electrical > Main Body > Active Test 

   Tester Display
   Front Fog Light Relay

   OK

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

   Result

   Proceed to
   OK
   NG

Result: 

OK 

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to  PROBLEM SYMPTOMS TABLE [10/2015 - 12/2017]  , or refer to  PROBLEM SYMPTOMS TABLE [12/2017 - 03/2018]  , or refer to  PROBLEM SYMPTOMS TABLE [03/2018 - 08/2019] 

Result: 

NG 

See step  3

1. Using a voltmeter, check the signal reading of the semiconductor pwr integration ECU.

   Refer to ON-VEHICLE INSPECTION [10/2015 - ]

   OK

   Output signal reading is normal.

   Result

   Proceed to
   OK
   NG

Result: 

NG 

INSPECT SEMICONDUCTOR POWER INTEGRATION ECU (RESULTS OF SIGNAL READING CHECK). Refer to  PROCEDURE - Step 2 

Result: 

OK 

See step  4

1. Remove the semiconductor pwr integration ECU from the engine room relay block and junction block assembly.

   Refer to REMOVAL [10/2015 - 08/2016] , or refer to REMOVAL [08/2016 - 03/2018] , or refer to REMOVAL [03/2018 - 08/2019]

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a

   Component without semiconductor pwr integration ECU connected (Engine Room Relay Block and Junction Block Assembly)

   -

   -

2. Measure the voltage according to the value (s) in the table below.

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   B-1 (BATT) - Body ground	Power switch off	11 to 14 V
   A-1 (ALT) - Body ground	Power switch off	11 to 14 V
   1D-11 (FMIG) - Body ground	Power switch on (IG)	11 to 14 V
   1E-4 (TAIL) - Body ground	Power switch off, light control switch in tail or head position	11 to 14 V

3. Measure the resistance according to the value (s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   1D-14 (GND1) - Body ground	Always	Below 1 Ω
   1G-5 (GND2) - Body ground	Always	Below 1 Ω

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  5

1. Disconnect the 2C instrument panel junction block assembly connector.
2. Measure the resistance according to the value (s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   1D-7 (-S) - 2C-25	Always	Below 1 Ω
   1D-7 (-S) or 2C-25 - Body ground	Always	10 kΩ or higher

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  6

1. Remove the instrument panel junction block assembly.

   Refer to REMOVAL [10/2015 - 08/2016] , or refer to REMOVAL [08/2016 - 03/2018] , or refer to REMOVAL [03/2018 - 08/2019]

2. Remove the main body ECU (multiplex network body ECU) from the instrument panel junction block assembly.
3. Measure the resistance according to the value (s) in the table below.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a

   Component without harness connected (Instrument Panel Junction Block Assembly)

   -

   -

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   2C-25 - MB-7 (FFGO)	Always	Below 1 Ω

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY. Refer to  REMOVAL [10/2015 - 08/2016]  , or refer to  REMOVAL [08/2016 - 03/2018]  , or refer to  REMOVAL [03/2018 - 08/2019] 

Result: 

OK 

See step  7

1. Replace the semiconductor pwr integration ECU with a new or known good one.

   Refer to REMOVAL [10/2015 - 08/2016] , or refer to REMOVAL [08/2016 - 03/2018] , or refer to REMOVAL [03/2018 - 08/2019]

2. Check that the front fog lights operate normally.

   OK

   Front fog lights operate normally.

   Result

   Proceed to
   OK
   NG

Result: 

OK 

END (SEMICONDUCTOR PWR INTEGRATION ECU WAS DEFECTIVE) 

Result: 

NG 

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU). Refer to  REMOVAL [10/2015 - 08/2016]  , or refer to  REMOVAL [08/2016 - 03/2018]  , or refer to  REMOVAL [03/2018 - 08/2019]