Toyota Tundra Service Manual: Headlight Dimmer Switch Circuit

DESCRIPTION

The main body ECU (multiplex network body ECU) receives the following signals:

  • Light control switch in off*1, DRL-Off*2, tail, head or Auto position
  • Headlight dimmer switch in high, low or high flash (pass) position
  • Fog light switch front position*3
    • *1: w/o DRL Off Switch
    • *2: w/ DRL Off Switch
    • *3: w/ Fog Light

WIRING DIAGRAM

PROCEDURE

1.

READ VALUE USING TECHSTREAM

(a) Using the Techstream, read the Data List.

Click here

Main Body

Tester Display

Measurement Item / Range

Normal Condition

Diagnostic Note

Dimmer SW

Headlight dimmer switch High position signal / OFF or ON

OFF: Headlight dimmer switch not in High position

ON: Headlight dimmer switch in High position

-

Passing Light SW

Headlight dimmer switch Flash position signal / OFF or ON

OFF: Headlight dimmer switch not in Flash position

ON: Headlight dimmer switch in Flash position

-

Front Fog Light SW

Fog light switch front position signal

OFF: Fog light switch off

ON: Fog light switch in front position

w/ Fog Light

Auto Light SW

Light control switch Auto position signal

OFF: Light control switch not in Auto position

ON: Light control switch in Auto position

-

Head Light SW (Head)

Light control switch Head position signal

OFF: Light control switch not in Head position

ON: Light control switch in Head position

-

Head Light SW (Tail)

Light control switch Tail position signal

OFF: Light control switch not in Tail position

ON: Light control switch in Tail position

-

OK:

Normal condition listed above are displayed.

OK

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

NG

2.

INSPECT HEADLIGHT DIMMER SWITCH ASSEMBLY

(a) Remove the headlight dimmer switch assembly.

Click here

(b) Inspect the headlight dimmer switch assembly.

Click here

NG

REPLACE HEADLIGHT DIMMER SWITCH ASSEMBLY

OK

3.

CHECK HARNESS AND CONNECTOR (HEADLIGHT DIMMER SWITCH ASSEMBLY - MAIN BODY ECU [MULTIPLEX NETWORK BODY ECU] AND BODY GROUND)

(a) Disconnect the J10 headlight dimmer switch assembly connector.

(b) Disconnect the J165 main body ECU (multiplex network body ECU) connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

*: w/ Fog Light

J165-10 (HF) - J10-17 (HF)

Always

Below 1 Ω

J165-24 (HU) - J10-11 (HU)

Always

Below 1 Ω

J165-22 (TAIL) - J10-18 (T)

Always

Below 1 Ω

J165-12 (HEAD) - J10-20 (H)

Always

Below 1 Ω

J165-8 (A) - J10-19 (A)

Always

Below 1 Ω

J165-26 (FFOG) - J10-4 (BFG)*

Always

Below 1 Ω

J10-12 (EL) - Body ground

Always

Below 1 Ω

J10-3 (LFG) - Body ground*

Always

Below 1 Ω

J165-10 (HF) or J10-17 (HF) - Body ground

Always

10 kΩ or higher

J165-24 (HU) or J10-11 (HU) - Body ground

Always

10 kΩ or higher

J165-22 (TAIL) or J10-18 (T) - Body ground

Always

10 kΩ or higher

J165-12 (HEAD) or J10-20 (H) - Body ground

Always

10 kΩ or higher

J165-8 (A) or J10-19 (A) - Body ground

Always

10 kΩ or higher

J165-26 (FFOG) or J10-4 (BFG) - Body ground*

Always

10 kΩ or higher

OK

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

    Headlight (HI-BEAM) Circuit

    Headlight Relay Circuit

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