Low Beam Headlight Circuit [09/2014 - 03/2019]: Procedure

1. Connect the Techstream to the DLC3.
2. Turn the engine 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
   Headlight Relay	Headlight relay (Low beam headlights)	ON/OFF	-

   Body Electrical > Main Body > Active Test 

   Tester Display
   Headlight Relay

   OK

   Headlight relay operates. (Low beam headlights illuminate.)

   Result

   Proceed to
   OK
   NG

Result: 

OK 

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to  PROBLEM SYMPTOMS TABLE [09/2014 - 03/2019] 

Result: 

NG 

See step  2

1. Remove the semiconductor pwr integration ECU from the No. 2 engine room relay block and No. 2 junction block assembly.

   Refer to REMOVAL [09/2014 - ]

2. Inspect the semiconductor pwr integration ECU.

   Refer to INSPECTION [09/2014 - ]

   Result

   Semiconductor pwr integration ECU is normal.

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPLACE SEMICONDUCTOR PWR INTEGRATION ECU. Refer to  REMOVAL [09/2014 - ] 

Result: 

OK 

See step  3

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

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   2B-1 (BATT) - Body ground	Always	11 to 14 V

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  4

1. Disconnect the 4C 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
   2D-8 (HLLS) - 4C-29	Always	Below 1 Ω
   2D-8 (HLLS) - Body ground	Always	10 kΩ or higher

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  5

1. Remove the instrument panel junction block assembly.

   Refer to REMOVAL [09/2014 - ]

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
   4C-29 - MB-15 (HRLY)	Always	Below 1 Ω

   Result

   Proceed to
   OK
   NG

Result: 

OK 

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU). Refer to  REMOVAL [09/2014 - ] 

Result: 

NG 

REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY. Refer to  REMOVAL [09/2014 - ]