converting polarity issue

I am having a weird issue when doing a simple polarity conversion for use with a positive door trigger input. I have a Viper 5901 installed on my 09 Mazdaspeed 3. The factory door triggers show ground when the doors are closed and go to an open circuit when a door is open. I have the door triggers diode isolated and hooked up to the positive trigger input of the brain using a +12V source and resistor method. This is my issue, i have a 516L voice module hooked up to my alarm as well, and everything is connected and works properly except for the door trigger input to the voice module. The 516L only has a negative door trigger input, so I hooked up my relay to convert the polarity from pos to neg so I could hook up this input for my voice module (its only real purpose is for the module to announce "check doors" if you forget to close a door). I followed the diagram in the 516L manual as well as the diagram on this forum for converting polarity using a relay, and I tried two different relays, but still had the same issue.    I connected the positive door trigger wire to 85, ground to 86 and 30, and the negative door trigger input to the voice module to 87. The problem is when I hook up the relay with all four wires, something strange happens with the door triggers, and even if I have a door open the little light on the gauge cluster that indicates a door is open goes out. This seems like a need a diode somewhere, but I do not know where. I appreciate any help you guys can provide.

Without knowing the vehicle or Viper etc specifics, but based on your description.... It sounds to me like you do NOT need inversion. IE - a +ve trigger means from GND to +ve when triggered. I presume the trigger is the door(s) opening. And if the doors (switches) are GND when closed, then they go +ve when opened. That assumes a pull-up device - like a resistor or bulb etc. Note that often door switches are open (floating) when closed and closed when open. (Get that - open when closed and close when open - simple!) EG - a single-wire door switch is GND when the door is open and is floating when the door is closed (which opens the door switch). That's a traditional door switch that GNDs dome lights etc. (ie, hot dome lights that are +12V on one side, and the door switch or manual switch grounds the other side to light it.)    With that traditional wiring, the door switch is +12V when closed (because the dome light pulls it to +12V) and is GND when open - ie, it is a NEGATIVE going transition from +12V to 0V/GND when opening the door. But yes - your problem is probably a diodic one. (If diodic isn't a valid word, it is now.) It is usually a simple case of using two diodes, but in the right places AND directions. And often ticky to work out yet oh-so-simple when seeing it in a simple diagram. (I know - after decades of intent, recently I FINALLY fitted a headlight reminder to my vehicle - only 10 years & $1.50 - the 10 years because my latest vehicle found me in 1999-2000.) But first, can you confirm your door switch is as you describe. ie - it is not a single-wire grounded when door-is-open, but is closed (grounded) when the door is closed, else maybe a 2-wire switch that opens/closes +12V?

oldspark wrote: Without knowing the vehicle or Viper etc specifics, but based on your description.... It sounds to me like you do NOT need inversion. IE - a +ve trigger means from GND to +ve when triggered. I presume the trigger is the door(s) opening. And if the doors (switches) are GND when closed, then they go +ve when opened. That assumes a pull-up device - like a resistor or bulb etc. Note that often door switches are open (floating) when closed and closed when open. (Get that - open when closed and close when open - simple!) EG - a single-wire door switch is GND when the door is open and is floating when the door is closed (which opens the door switch). That's a traditional door switch that GNDs dome lights etc. (ie, hot dome lights that are +12V on one side, and the door switch or manual switch grounds the other side to light it.)    With that traditional wiring, the door switch is +12V when closed (because the dome light pulls it to +12V) and is GND when open - ie, it is a NEGATIVE going transition from +12V to 0V/GND when opening the door. But yes - your problem is probably a diodic one. (If diodic isn't a valid word, it is now.) It is usually a simple case of using two diodes, but in the right places AND directions. And often ticky to work out yet oh-so-simple when seeing it in a simple diagram. (I know - after decades of intent, recently I FINALLY fitted a headlight reminder to my vehicle - only 10 years & $1.50 - the 10 years because my latest vehicle found me in 1999-2000.) But first, can you confirm your door switch is as you describe. ie - it is not a single-wire grounded when door-is-open, but is closed (grounded) when the door is closed, else maybe a 2-wire switch that opens/closes +12V?

oldspark, thank you for your reply, but I am not sure if you just did not read my post, or you just missed the make and model of my car, as well as the model of alarm, but that information was in the first line of my post. Yes, I am sure that my door triggers are as I described, I installed the remote start and alarm myself and they are quite non traditional triggers.

No - I did not miss that info. Sorry for my vagueness - I simple meant that although I know what they are, I have no idea about the specifics involved - ie, I cannot confirm that the 09 Mazda is grounded-closed doors. (I do know 1990 323s and earlier are not.) It'll take a while for me to post a pic though.... (Maybe you have a simple "line" diagram or reference I could use or check?)

So you have 12vdc going through a resistor to a relay? That won't work as the resistor will limit the current most likely to the point that the relay won't have enough current to pull in. What is the size of the resistor? This would be a much better application for a reed relay or a transistor.Kevin Pierson

KPierson wrote: So you have 12vdc going through a resistor to a relay? That won't work as the resistor will limit the current most likely to the point that the relay won't have enough current to pull in. What is the size of the resistor? This would be a much better application for a reed relay or a transistor.

I was thinking the same thing, after talking another guy who is an installer I am going to try using the dome light positive wire to trigger the relay.

Forget about inverting, like Fords,(it's a Focus)the door pins go to OPEN CIRCUIT on that vehicle, two answers: On some Viper's, I know you can with the 5902, change the door pin configuration to open circuit via the programming. Or use the following DEI part for it. DTIMazda.

Thanks Howie, but the issue isn't with the door trigger to the alarm. I am just trying to switch over the positive door trigger to a negative signal to be connected to my voice module (because it only accepts a negative input), so it can say "check doors" if I leave a door open. Kind of pointless really, but I just like using all the available features when I install stuff.

Except it isn't positive! It's neg when the doors are closed and OPEN CIRCUIT when the doors a opened. Use the DTIMazda to get your neg signal.

howie ll wrote: Except it isn't positive! It's neg when the doors are closed and OPEN CIRCUIT when the doors a opened. Use the DTIMazda to get your neg signal.

I know that the triggers rest at ground when closed and Open circuit when open, I have already taken care of the door triggers by running a fused 12V source that splits off into four different branches (one for each trigger), each branch has a 10K resistor wired in. Then I have each of the triggers diode isolated and all four are connected to the single positive door trigger input for the alarm. That is what is causing the whole issue, when I try to hook up the relay using the lead from the positive input, it is allowing the positive signal to go to ground and the car thinks that no doors are open. I am going to attempt using the positive wire from the dome light to trigger the negative input instead, if that fails then I will just say screw it and go without this feature.