For 1990-2009 cars

### Horn Fuse

Location: Underhood fuse block
Type: 15 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: 150
Location: Horn connector cavity 2 to forward lamp ground splice pack cavity G.

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

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

• | Side marker lamps

• | Park/turn lamps

• | Cooling fan module

• | Fog lamps

• | Low washer

Check for OPENS/SHORTS. Repair as needed.

Ground: 550
Location: Connects the horn switch through the LIPFB cavity A1 through the roll connector cavity E.

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

• | Trunk release

• | Wipers switch

• | Glove box lamp

• | HVAC

• | Headlight switch

Check for OPEN/SHORTS.

Repair as needed.

### Power Circuits

Circuit 28

Location: Connects UHFB I/P connector cavity E3 (L81) or D3 (L61) to the base of the column connector cavity F and to the BCM cavity J3-B2.
Function: This circuit provides ground for the horn relay coil. The relay coil is grounded when the horn switch is closed, or the horn pad is depressed, or when commanded by the BCM.

Check for OPEN/SHORTS.

Repair as needed.

Circuit 29

Location: Connects the UHFB forward lamp connector cavity D4 to the horn connector cavity 1.
Function: This circuit provides power to the horn.

Check for OPEN/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 or replace as needed.

#### SIR/Cruise/Turn Coil Assembly

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

Check for OPENS/SHORTS in cavities E and F.

Repair as needed.

#### Horn Switch

Check resistance though the horn switch. The switch resistance should be less than 1 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 2-4 ohms.