adding horn beep to audiovox remote start

I have a 2008 Ford Fusion with an Audiovox APS57C remote start. It seems to work well but does not beep the horn, ever. I want the horn to beep when I lock the car. Can I simply add a relay to the "lock" signal wire and have it sound my horn? I'm sure I'm not the only person that likes to hear an audible sound when locking the car. I know other models of Audiovox systems sound the horn such as APS687 but from what I gather, it will sound the horn every time a function is used. lock, unlock, start, open trunk etc. I just want the lock function to beep the horn like the factory unit did when you double clicked the lock button. Thanks. Danford1

You may want to rethink the horn.  People always think they want that to happen, but the duration of the door lock output is probably going to be eternally long.  You may want to look into a Peizo buzzer from Radio Shack.

I agree and have tried this. The lock pulse is a full second and tho that doesn't soung long it is. The horn will be loud and long when you lock it. Horn pulses are very short, fractions of a second. Your Rs has an option to shorten the unlock pulse to 350ms but not the lock....Mike M2

Tech Manager

CS Dealer Services

Ok, I understand the 1 second lock signal.

What circuit or type of device can I use to turn the 1 second signal into a quick pulse to send to the relay?

Danford1

I was searching other areas of this forum. I found this in the relay area. https://www.the12volt.com/relays/page5.asp#ctm Couldn't I use this to shorten my 1 second pulse? If so, what is the part number for the diode? I see these diodes in a lot of diagrams but can't find a part number for them... Danford1

I'm trying to turn a 1 second +12V pulse to a reduced time pulse, 300-400 ms. I saw this relay diagram https://www.the12volt.com/relays/page5.asp#ctm It shows a diode like MANY other relay diagrams I've seen. No part number is ever given for it. I assume it is some generic diode. What part number can I use for this? Thanks. Danford1

The diode in that diagram is a 1N4001 or 1N4004 diode.  Either will work and they are available at the "shack".

FYI, what you are trying to accomplish is a standard feature on the Ultra Start remote starters.  You can

select 3 different horn output lengths ( 5ms, 10ms and 50ms ) and horn confirmation on all commands, lock & unlock only, second lock only or none.

Soldering is fun!

Thanks for the diode numbers. I have an Audiovox remote start that doesn't have the feature like the Ultrastart so I have to modify it :-) Is there a way to figure what size cap and resistor to use for a specific time delay? In the diagram it shows a 1K uf cap. Is that an electrolytic cap? If not, what kind is it? It says the time can be increased by changing the value of the cap. Would time be shortened with a bigger cap? Thanks. Danford1

The 1k uf capacitor is a 1,000 microfarad capacitor.  Electrolytic is the cheapest way to go.  Yes a larger cap will yield a shorter pulse.