Horn blowing constantly when Evo-All data link is disconnected

Question

Installed an Evo-All + Prestige APS-57E system on a 2015 Corolla S. I also enabled the Evo-Alarm function. Everything works perfectly. But I accidently noticed what I believe could be a bad unit issue...

 

If I disconnect the datalink connector of the Evo-All, the horn constanly blows.

 

I even disconnected ALL connectors from the Evo-All and connected just the Evo-All by itself to the 20-pin harness and the horn started blowing again?? I have never seen this happen before and am worried that if the vehicles battery was ever disconnected, the client's horn would just start blowing? 

 

Somehow, the Evo-All has an internal ground signal inside itself? I tried reseting it as well. I also disconneted the horn connector from the steering wheel column and the Evo-All would still send a ground signal to the horn wire and blow it.

 

Conencting the data-link conector stops this from happening the the Evo works fine again. Is this just a bad unit?

Answer 1

First of all, the 4 pin datalink connector should always be connected FIRST and disconnected LAST, since power and ground are all in this connector.

Disconnecting the datalink cable while all the other cables are still connected is highly not recommended since now the unit has no power, but more importantly, NO GROUND, so the unit will try to find ground itself wherever is can.

Disconnecting the datalink while everything else is connected can also damage certain input and outputs on the evo-all.

Thank you,

Comments

Thanks for the advice. Will take note hence forth.

Answer 2

An electronic device that is not grounded properly will start looking for a ground. I've seen this happen a few times where the unit would ground itself through its own door status output when a door was open (systems works fine when the door  is opened but and acts up when it's closed).

 

Side note about the EVO-ALARM feature. It completely reconfigures your 20-pin inputs and outputs.

One of the changes is that what is normally and analog output for door status, becomes and output for the Horn!

 

I'm sure you've seen it, but here's the EVO-ALARM guide. Grab any of the connections in there (they all the same really) , but you'll notice all the pin-outs completely change.  http://fortin.ca/download/16221/16221.pdf