Low Beam Headlight 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 that the relay operates.
   MAIN BODY
   
   

   Tester Display	Test Part	Control Range	Diagnostic Note
   Headlight Relay	Headlight relay (Low beam headlights)	ON/OFF	-

   OK

   Headlight relay operates. (Low beam headlights illuminate.)

NG → See step   2 

OK → See step   7 

1. Remove the H-LP relay from the engine room relay block.
2. Measure the resistance according to the value(s) in the table below.
   Fig 1: Identifying H-LP Relay

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Standard Resistance

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

   TEXT IN ILLUSTRATION
   
   

   *a	Component without harness connected (H-LP relay)

NG → REPLACE H-LP RELAY 

OK: Go to next step 

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

   Standard Voltage

   Tester Connection	Switch Condition	Specified Condition
   Relay Terminal 2 - Body ground	Always	11 to 14 V
   Relay Terminal 5 - Body ground	Always	11 to 14 V

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Disconnect the A24*1 or A17*2 headlight assembly LH connector.
2. Disconnect the A66*1 or A60*2 headlight assembly RH connector.
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   *1:
   
   

   Tester Connection	Condition	Specified Condition
   Relay Terminal 3 - A24-2 (LO)	Always	Below 1 Ω
   Relay Terminal 3 - A66-2 (LO)	Always	Below 1 Ω
   Relay Terminal 3 - Body ground	Always	10 kΩ or higher

   *2:
   
   

   Tester Connection	Condition	Specified Condition
   Relay Terminal 3 - A17-2 (LO)	Always	Below 1 Ω
   Relay Terminal 3 - A60-2 (LO)	Always	Below 1 Ω
   Relay Terminal 3 - Body ground	Always	10 kΩ or higher

   • *1: for HID Headlight
   • *2: for Halogen Headlight

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Disconnect the 3D 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
   Relay Terminal 1 - 3D-12	Always	Below 1 Ω
   Relay Terminal 1 - Body ground	Always	10 kΩ or higher

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Remove the instrument panel junction block assembly. Refer to REMOVAL .
2. Remove the main body ECU (multiplex network body ECU) from the instrument panel junction block assembly.
   Fig 2: Inspecting Instrument Panel Junction Block Assembly Connector Terminals

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

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   3D-12 - MB-15 (HRLY)	Always	Below 1 Ω
   3D-12 - Body ground	Always	10 kΩ or higher

   TEXT IN ILLUSTRATION
   
   

   *a	Component without harness connected (Instrument Panel Junction Block Assembly)

NG → See step   8 

OK → See step   9