Toyota Yaris: Theft Deterrent System / Horn Circuit

Toyota Yaris XP210 (2020-2026) Reapir and Service Manual / Vehicle Interior / Theft Deterrent / Keyless Entry / Theft Deterrent System / Horn Circuit

DESCRIPTION

When the theft deterrent system is switched from the armed state to the alarm sounding state, the main body ECU (multiplex network body ECU) transmits a signal to cause the horn to sound at intervals of 0.4 seconds.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

If the main body ECU (multiplex network body ECU) is replaced, refer to the Registration.

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PROCEDURE

1.

CHECK HORNS OPERATION

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

Result

Proceed to

Horns sound

A

Horns do not sound

B
B

GO TO HORN SYSTEM

A

2.

CHECK HARNESS AND CONNECTOR (POWER DISTRIBUTION BOX ASSEMBLY - AUXILIARY BATTERY)

(a) Disconnect the 4D power distribution box assembly connector.

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

Standard Voltage:

Tester Connection

Switch Condition

Specified Condition

4D-11 - Body ground

Ignition switch off

11 to 14 V
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

3.

INSPECT POWER DISTRIBUTION BOX ASSEMBLY

(a) Remove the power distribution box assembly.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

4D-11 - MB-23 (HORN)

Always

Below 1 Ω

*a

Component without harness connected

(Power Distribution Box Assembly)
OK

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

NG

REPLACE POWER DISTRIBUTION BOX ASSEMBLY

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    Categories

    Break-In Period

    No special break-in is necessary, but a few precautions in the first 600 miles (1,000 km) may add to the performance, economy, and life of the vehicle.

    Do not race the engine. Do not maintain one constant speed, either slow or fast, for a long period of time. Do not drive constantly at full-throttle or high engine rpm for extended periods of time. Avoid unnecessary hard stops. Avoid full-throttle starts.

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