Inspection Procedure

WARNING: This page is about a different car, the 2002 Toyota Prius. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Steps 1-2 are based on the premise that the horns blow normally whenever the horn switch is operated. If horn operation is not normal when the horn switch is operated, check the horn switch.

Check voltage between terminal 1 of theft deterrent horn connector and body ground.

Fig 1: Verifying Voltage At Horn Connector
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

PREPARATION:

Remove the theft deterrent horn and disconnect the connector.

CHECK:

Measure voltage between terminal 1 of theft deterrent horn connector and body ground.

OK:

Voltage: 10-14 V
1. NG: Check and repair harness and connector between HORN fuse and theft deterrent horn.
2. OK: Go to next step.
Check theft deterrent horn.
CHECK:

Connect positive (+) lead to terminal 1 and negative (-) lead to ground to theft deterrent horn connector.

OK:

Theft deterrent horn blows.

Fig 2: Testing Horn By Applying Battery Voltage
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
1. NG: Replace theft deterrent horn.
2. OK: Go to next step.
Check harness and connector between body ECU and theft deterrent horn . See HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE .
1. NG: Check and repair harness or connector.
2. OK: Go to next step.
Check and replace body ECU.