Toyota Prius: Horn System

Precaution

PRECAUTION

PRECAUTIONS FOR DISCONNECTING AND RECONNECTING CABLE TO NEGATIVE (-) AUXILIARY BATTERY TERMINAL

Parts Location

PARTS LOCATION

ILLUSTRATION

*1

LOW PITCHED HORN ASSEMBLY

*2

NO. 1 ENGINE ROOM RELAY BLOCK AND NO. 1 JUNCTION BLOCK ASSEMBLY - HORN RELAY - HORN FUSE

ILLUSTRATION

*1	HORN BUTTON ASSEMBLY	*2	SPIRAL CABLE SUB-ASSEMBLY
*3	MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)	*4	POWER DISTRIBUTION BOX ASSEMBLY

System Diagram

SYSTEM DIAGRAM

Problem Symptoms Table

PROBLEM SYMPTOMS TABLE

NOTICE:

Before replacing the main body ECU (multiplex network body ECU), refer to Service Bulletin.

HINT:

Use the table below to help determine the cause of problem symptoms. If multiple suspected areas are listed, the potential causes of the symptoms are listed in order of probability in the "Suspected Area" column of the table. Check each symptom by checking the suspected areas in the order they are listed. Replace parts as necessary.

Horn System

Symptom	Suspected Area	Link
Horn does not sound	HORN fuse	-
	HORN relay
	Horn button assembly
	Spiral cable sub-assembly
	Power distribution box assembly
	Harness or connector	-
Horn sounds all the time	HORN relay
	Horn button assembly
	Spiral cable sub-assembly
	Power distribution box assembly
	Main body ECU (Multiplex network body ECU)
	Harness or connector	-

Data List / Active Test

DATA LIST / ACTIVE TEST

ACTIVE TEST

HINT:

Using the GTS to perform Active Tests allows relays, VSVs, actuators and other items to be operated without removing any parts. This non-intrusive functional inspection can be very useful because intermittent operation may be discovered before parts or wiring is disturbed. Performing Active Tests early in troubleshooting is one way to save diagnostic time. Data List information can be displayed while performing Active Tests.

(a) Perform the Active Test according to the display on the GTS.

Body Electrical > Main Body > Active Test

Tester Display	Measurement Item	Control Range	Diagnostic Note
Toyota Prius Vehicle Horn	Vehicle horn	OFF / ON	-