For 1990-2009 cars

### Horn Fuse

Location: Underhood Fuse Block

Type: 10 amp mini fuse

Feeds: Circuit 28 and 29 of the horn relay

This fuse feeds only the horn relay. If the fuse is blown determine the cause of the blown fuse and repair. Replace the fuse as needed.

### Grounds

Before checking the ground circuit from the faulty component all the way to the ground stud, check the circuit from the splice pack to ground by testing some of the other subsystems grounded by the same splice pack. If the other subsystems function properly, the path from the splice pack-to-ground is good.

Ground: Circuit 150

Location: Horn connector cavity A to underhood fuse block cavity E7; then from underhood fuse block cavity E6 to left forward lamp ground.

Important: Due to the manufacturing process the cavity shown on the schematics may not match the harness.

If the following circuits are operating normally, the ground is most likely good.

• | Left Side Marker Lamp

• | Left Park/Turn Lamp

• | Left Fog Lamp

Check for OPENS/SHORTS. Repair as needed.

### Power Circuits

#### Circuit 28

Location: Connects UHFB connector cavity F9 to the base of the column connector cavity A back through UHFB to cavity E9 then to BCM cavity J3-B7.

Function: This circuit provides ground for the horn relay coil. The relay coil is grounded when the horn switch is closed (the horn pad is depressed) or when commanded by the BCM.

Check for OPENS/SHORTS.

Repair as needed.

#### Circuit 29

Location: Connects UHFB connector cavity D10 to horn connector cavity B.

Function: This circuit provides power to the horn.

Check for OPENS/SHORTS.

Repair as needed.

### Components

#### Horn Relay

Find a relay that is interchangeable with the horn relay to see if this fixes the horn circuit.

Repair/Replace as needed.

#### SIR/Cruise/Turn Coil Assembly

Check resistance through the coil assembly by measuring voltage at horn switch and rotating steering wheel.

Check for OPENS/SHORTS in cavities A (column side) and cavity 3 (steering wheel side). Repair as needed.

#### Horn Switch

Check resistance through horn switch. The switch resistance should be less than one ohm when the horn pad is depressed and open when the horn pad is not depressed.

Check for OPENS/SHORTS.

Repair as needed.

#### Horn

Check resistance through the horn. Horn resistance should be 2 to 4 ohms.