Symptom Chart

WARNING: This page is about a different car, the 2003 Ford Pickup, 2003 Ford F550 Super Duty, 2003 Ford F450 Super Duty, 2003 Ford Excursion, and 2003 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.

SYMPTOM CHART

Condition	Possible Sources	Action
The horn does not sound	Circuitry Horn relay Horn switch Horn Speed control servo or jumper Powertrain control module Vehicle security module	Go To PINPOINT TEST A .
The horn sounds continuously	Horn relay Circuitry Horn switch Vehicle security module	Go To PINPOINT TEST B .
No communication with the vehicle security module	Circuitry Vehicle security module	REFER to MULTIFUNCTION ELECTRONIC MODULE - EXCURSION & F250-F550 SUPER DUTY PICKUPS .