How do you reset the alarm system?

Answered in your previously asked question. Do you know if there is an aftermarket alarm system added on to your vehicle? Sure seems like it. Look under the dash for a box or unusual device with possibly a light on it. Other than that, low battery voltage can cause unexpected sounding of the horn when starting the vehicle. Ensure your battery is fully charged and good - able to sustain a load. www.repairpal.com/repair-shops