Normal Lighting Operation; Light Auto Turn Off Operation - Toyota Tundra 2003 Electrical Wiring Diagram

SYSTEM OUTLINE
With the ignition SW turned on, the current flows to TERMINAL 9 of the integration relay through ECU IG fuse.
Voltage is applied at all times to TERMINAL 6 of the integration relay through the TAIL fuse, and through the H–LP relay coil
side.

1. NORMAL LIGHTING OPERATION

<Turn taillight on>
With the light control SW turned to TAIL position, a signal is input into the integration relay. Due to this signal, the current
flowing to TERMINAL 6 of the relay flows to TERMINAL 14 of the light control SW to TERMINAL 16 to GROUND, and
taillights to turn on.
<Turn headlight on>
With the light control SW turned to HEAD position, a signal is input into the integration relay. Due to this signal, the current
flowing to the relay flows to TERMINAL 13 of the light control SW to TERMINAL 16 to GROUND in the headlight circuit, and
causes taillight and H–LP relay to turn the lights on. The taillight circuit is same as above.

2. LIGHT AUTO TURN OFF OPERATION

With light on and ignition SW turned off (Input signal goes to TERMINAL 9 of the relay), when the driver's door is opened
(Input signal goes to TERMINAL 14 of the relay), the relay operates and the current is cut off which flows from TERMINAL 6
and through the H–LP relay coil side of the relay to taillight circuit and headlight circuit.
As a result, all lights are turned off automatically.
SERVICE HINTS
H–LP RELAY
5–3 : Closed with the light control SW at HEAD position or the dimmer SW at FLASH position
Closed with the engine running and the parking brake lever released
C15 LIGHT CONTROL SW [COMB. SW]
13–16 : Closed with light control SW at HEAD position
14–16 : Closed with light control SW at TAIL or HEAD position
D16 DOOR COURTESY SW FRONT LH
1–GROUND : Continuity with the front LH door open
INTEGRATION RELAY
9–GROUND : Approx. 12 volts with the ignition SW at ON position
14–GROUND : Continuity with the front LH door open
3, 6–GROUND : Always approx. 12 volts
8–GROUND : Always continuity
: PARTS LOCATION
Code See Page
C15 34
36 (Access Cab)
D16 D16
37 (Standard Cab)
: RELAY BLOCKS
Code See Page
2 21
: JUNCTION BLOCK AND WIRE HARNESS CONNECTOR
Code See Page
1C
1H 26 (*1) ( )
1J
1K 26 (*1)
1N
27 (*1) 27 (*1)
1O
* 1 : w/ Daytime Running Light
Code
J3
J4
J7
Relay Blocks (Relay Block Location)
Engine Room R/B (Engine Compartment Left)
Junction Block and Wire Harness (Connector Location)
Cowl Wire and Driver Side J/B (Lower Finish Panel)
Engine Room Main Wire and Driver Side J/B (Lower Finish Panel)
Cowl Wire and Driver Side J/B (Lower Finish Panel) Cowl Wire and Driver Side J/B (Lower Finish Panel)
* 2 : w/o Daytime Running Light
2003 TOYOTA TUNDRA (EWD491U)
See Page
35
35
35
( )
* 3 : Bench Seat
Code
J13 35
J21 A 35
J22 B 35
* 4 : Separate Seat, Captain Seat (w/o Power Seat)
See Page
125