Toyota 4Runner manuals

Toyota 4Runner: Horn Circuit

DESCRIPTION

When the theft deterrent system is in the alarm sounding state, the main body ECU outputs a signal repeatedly at 0.4 second intervals, causing the horn(s) to sound.

WIRING DIAGRAM


PROCEDURE

1.

CHECK HORN OPERATION

(a) Press the horn switch and check if the horn(s) sound.

OK:

Horn(s) operate normally.


NG

GO TO HORN SYSTEM


OK

2.

PERFORM ACTIVE TEST USING TECHSTREAM (VEHICLE HORN)

(a) Operate the Techstream according to the steps on the display and select Active Test (See page ).


Main Body

Tester Display

Test Part

Control Range

Diagnostic Note

Vehicle Horn

Vehicle horn(s)

ON/OFF

-

OK:

Horn(s) operate normally.


OK

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE


NG

3.

CHECK HARNESS AND CONNECTOR (NO. 1 INTEGRATION RELAY - MAIN BODY ECU)

(a) Disconnect the 1C relay connector.

(b) Remove the main body ECU (See page ).


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

Standard Resistance:

Tester Connection

Condition

Specified Condition

1C-7 - A-28 (HORN)

Always

Below 1 Ω

1C-7 or A-28 (HORN) - Body ground

Always

10 kΩ or higher


OK

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)


NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

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