problems with audiovox prestige aps 785

The 556U requires, as Howie points out, +12V, Ground, and Ground While Running.  The manual is available in the Download section of this site.

Cesart connected 12V and Ground while running (Status output), but not ground.

To address Cezart's question, the 556U black lead needs to be connected to a solid vehicle ground.   With your multimeter, place the red meter lead on a 12volt signal in the car (in the fuse panel, perhaps).  Place the black meter lead on your potential ground point (dash bracket, for example), and make sure the meter reads 12 volts.   It may be easiest to use an existing bolt in the area you choose, as long as your meter indicates it is a good ground. 

You should use a ring terminal on the end of your ground wire, either soldered or crimped (I prefer solder, just my opinion).  Remove the bolt and replace with the ring terminal on the bolt, and retighten.  That should do it.

Guys,

So first of all, I would like to thank all of you for all your advices and patience. THANK YOU VERY MUCH!

Now – the details: certainly grounding the black wire helped (I could hear the by-pass box clicking). What also helped was identifying which cable was +12V (it was the orange one, not the light blue as I assumed based on connections to the relay – thank you, Lectric Guy for letting me know how to do it).

Cezaryt-

 Glad to hear your Remote Start is working.   As far as your question regarding the fuses--yes, absolutely normal.  Some fuses are in line with items only on when the key is inserted and in turned to the ACC or On position, such as your radio.  The supply to these fuese will only be active when the key is inserted and switched to that position.   Other fuses are in line with items always powered, such as headlights.  The supply to these fuses will always have power.

 It is common for Channel 3 of the remote start to be used for trunk release, and is activated by holding down the key/trunk button for 3 seconds.  Sometimes this delay can be annoying to customers and installers use another channel, such as channel 4 to provide instant response trunk release.

 These signals are pulsed low when activated, and are intended to drive a low current circuit or a relay, and may be used for a number of things such as trunk release, defrost control, window rollup/roll down, etc.  Please be aware that additional components or modules would be required for some of these tasks.

 As far as Garage Door Openers, I believe Audiovox made a unit that interfaced to garage door openers and was compatible with remotes, but I don't believe these units are available any longer. 

Lectric Guy,

Yes, the remote start works, and I use it from time to time just for fun. ;-)

Thank you very much, one more time, for all your help.