Lighting (ext)

Light Control Switch Circuit

~4min read
DESCRIPTION

The main body ECU (driver side junction block assembly) receives the following switch information:

  • Light control switch position off, tail, head or AUTO
  • Dimmer switch position high, low or high flash (pass)
  • Fog light switch position on or off
WIRING DIAGRAM
PROCEDURE
  1. READ VALUE USING TECHSTREAM

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(c) Turn the Techstream on.

(d) Enter the following menus: Body Electrical / Main Body / Data List.

(e) Read Data List according to the display on the Techstream.

Main Body

Tester Display

Measurement Item/Range

Normal Condition

Diagnostic Note

Dimmer Hi SW

Dimmer switch high position signal/ON or OFF

ON: Dimmer switch in high or high flash (pass) position

OFF: Dimmer switch in low position

-

Passing Light SW

Dimmer switch high flash (pass) position signal/ON or OFF

ON: Dimmer switch in high flash (pass) position

OFF: Dimmer switch not in high flash (pass) position

-

Front Fog Light SW

Front fog light switch signal/ON or OFF

ON: Front fog light switch on

OFF: Front fog light switch off

-

Auto Light SW

Light control switch AUTO position signal/ON or OFF

ON: Light control switch in AUTO position

OFF: Light control switch not in AUTO position

-

Head Light SW (Head)

Light control switch head position signal/ON or OFF

ON: Light control switch in head position

OFF: Light control switch not in head position

-

Head Light SW (Tail)

Light control switch tail position signal/ON or OFF

ON: Light control switch in tail or head position

OFF: Light control switch in neither tail nor head position

-

OK:

Normal conditions listed above are displayed.


OK

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

NG
  1. INSPECT HEADLIGHT DIMMER SWITCH ASSEMBLY

HINT:

Inspect the items that did not change as a result of monitoring the Data List.

(a) Remove the headlight dimmer switch assembly (See page ).

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

Standard Resistance:

Light Control Switch

Tester Connection

Condition

Specified Condition

12 (EL) - 18 (T)

OFF

10 kΩ or higher

18 (T) - 19 (A)

OFF

10 kΩ or higher

19 (A) - 20 (H)

OFF

10 kΩ or higher

12 (EL) - 18 (T)

TAIL

Below 1 Ω

12 (EL) - 18 (T)

HEAD

Below 1 Ω

18 (T) - 20 (H)

HEAD

Below 1 Ω

12 (EL) - 19 (A)

AUTO

Below 1 Ω

Dimmer Switch

Tester Connection

Condition

Specified Condition

11 (HU) - 12 (EL)

LOW

10 kΩ or higher

11 (HU) - 12 (EL)

HIGH

Below 1 Ω

12 (EL) - 17 (HF)

HIGH FLASH

Below 1 Ω

Fog Switch

Tester Connection

Condition

Specified Condition

3 (LFG) - 4 (BFG)

OFF

10 kΩ or higher

3 (LFG) - 4 (BFG)

ON

Below 1 Ω

OK:

Headlight dimmer switch assembly is normal.

Text in Illustration

*a

Component without harness connected:

(Headlight Dimmer Switch Assembly)


NG

REPLACE HEADLIGHT DIMMER SWITCH ASSEMBLY

OK
  1. CHECK HARNESS AND CONNECTOR (MAIN BODY ECU (DRIVER SIDE JUNCTION BLOCK ASSEMBLY - HEADLIGHT DIMMER SWITCH ASSEMBLY

(a) Disconnect the D33 headlight dimmer switch assembly connector.



(b) Disconnect the D49, D50 and 2N main body ECU (driver side junction block assembly) connectors.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

D33-4 (BFG) - D49-28 (FFOG)

Always

Below 1 Ω

D33-11 (HU) - 2N-2 (HU)

Always

Below 1 Ω

D33-17 (HF) - D50-13 (HF)

Always

Below 1 Ω

D33-18 (T) - D50-23 (TAIL)

Always

Below 1 Ω

D33-19 (A) - D50-21 (A)

Always

Below 1 Ω

D33-20 (H) - D49-17 (HEAD)

Always

Below 1 Ω

D33-3 (LFG) - Body ground

Always

Below 1 Ω

D33-4 (BFG) - Body ground

Always

10 kΩ or higher

D33-11 (HU) - Body ground

Always

10 kΩ or higher

D33-17 (HF) - Body ground

Always

10 kΩ or higher

D33-18 (T) - Body ground

Always

10 kΩ or higher

D33-19 (A) - Body ground

Always

10 kΩ or higher

D33-20 (H) - Body ground

Always

10 kΩ or higher

D33-12 (EL) - Body ground

Always

Below 1 Ω

Text in Illustration

*a

Front view of wire harness connector

(to Headlight Dimmer Switch Assembly)

*b

Front view of wire harness connector

(to Main Body ECU (Driver Side Junction Block Assembly))

*c

Front view of wire harness connector

(to Main Body ECU (Driver Side Junction Block Assembly))

*d

Front view of wire harness connector

(to Main Body ECU (Driver Side Junction Block Assembly))


OK

REPLACE MAIN BODY ECU (DRIVER SIDE JUNCTION BLOCK ASSEMBLY)


NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

Test yourself

A quick Toyota Venza quiz: every answer comes with an explanation and a link to the manual page.