Toyota Tundra Service Manual: IG Signal Circuit

Toyota Tundra Service Manual / Vehicle Interior / Lighting / Lighting System / IG Signal Circuit

DESCRIPTION

This circuit detects the ignition switch ON or off condition, and sends it to the main body ECU (multiplex network body ECU).

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

Inspect the fuses for circuits related to this system before performing the following procedure.

PROCEDURE

1.	READ VALUE USING TECHSTREAM

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

Click here

Main Body

Tester Display

Measurement Item / Range

Normal Condition

Diagnostic Note

IG SW

Ignition switch signal / OFF or ON

OFF: Ignition switch off

ON: Ignition switch ON

"OFF" is also displayed for this item when the ignition switch is ACC.

OK:

Normal conditions listed above are displayed.

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

2.	CHECK HARNESS AND CONNECTOR (DRIVER SIDE JUNCTION BLOCK ASSEMBLY - BATTERY AND BODY GROUND)

(a) Disconnect the driver side junction block assembly connectors.

Front view of wire harness connector

(to Driver Side Junction Block Assembly)

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
3G-1 - Body ground	Always	11 to 14 V
3J-17 - Body ground	Ignition switch ON	11 to 14 V
3J-17 - Body ground	Ignition switch off	Below 1 V

Standard Resistance:

Tester Connection	Condition	Specified Condition
3I-3 - Body ground	Always	Below 1 Ω

REPAIR OR REPLACE HARNESS OR CONNECTOR

3.	CHECK DRIVER SIDE JUNCTION BLOCK ASSEMBLY

(a) Remove the driver side junction block assembly.

Click here

Component without harness connected

(Driver Side Junction Block Assembly)

(b) Remove the main body ECU (multiplex network body ECU) from the driver side junction block assembly.

Click here

Standard Resistance:

Tester Connection

Condition

Specified Condition

A-32 (IG) - 3G-1

Battery not connected to 3J-17 and 3I-3

10 kΩ or higher

Battery positive (+) → 3J-17

Battery negative (-) → 3I-3

Below 1 Ω

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

REPLACE DRIVER SIDE JUNCTION BLOCK ASSEMBLY

How To Proceed With Troubleshooting

Interior Light Auto Cut Circuit

See More:

Toyota Tundra Owners Manual > Operating the lights and wipers: Headlight switch
The headlights can be operated manually or automatically. Operating instructions Operating the switch turns on the lights as follows: For U.S.A. The headlights, daytime running lights and all the lights listed above turn on and off automatically. (When the engine switch is in the "ON" position.) &n ...