diode to door trigger

ok, so i work on police cars  installing things for a to z. recently doing an alarm i did some research and found out you have to put a diode going to the door input trigger( -) , stripe away so like this...-------|<------- to trigger input on alarm(negative input)why is it that the diode has to face this way and not ----------->|-----------is it because the trigger input wire is more possitive then the negative signal from the door triggersi am puzzledthanks for any help

i found that link but is what i thot right? alarm side is more positive so thats why the diodes are reversed like that? if i am wrong , i am looking for an answer, ty

I get confused on diodes too, it helps to only think of it flowing positive. Positive flows from the anode to the cathode (strip side), The door trigger sees a negative, so positive has to flow from the alarm to the door wire. When the door is opened the power goes from the alarm to ground making the wire a ground. Am I close?

What kind of vehicle?    Does the vehicle have 4 seperate door open indicators on the dash of the vehicle?   If so the reason for the diode isolation is to keep the door open indicators working properly.  The diode is a directional device, if it is installed backwards the signal from the pinswitch will not reach the alarm.  The link I posted earlier has the 4 pictures of the diodes that show which way a particular voltage will or will not flow through the diode. 

what i am trying to say is the alarm has a negative door trigger input, and i have to put a diode on each door trigger in the BCM of an impala, but i understand that a diode flows positive to neg, anode to cathode, but i am confused on how when u need to send a negative output to the alarm u have to have the diode looking like thisthis end is negative trigger from BCM when door opens---------|<-----------this is the door trigger input to the alarm      so this means, if u are sending a ground signal to the alarm, u have to have the diode opposite to what u would normally put it( --------->|-------- )its just so confusing trying to learn new things

reax222 wrote: I get confused on diodes too, it helps to only think of it flowing positive. Positive flows from the anode to the cathode (strip side), The door trigger sees a negative, so positive has to flow from the alarm to the door wire. When the door is opened the power goes from the alarm to ground making the wire a ground. Am I close?

this kinda makes sense but doesnt at the same time lol :P

i am an idiot wrote: Third picture down shows which way negative voltage travels through the diode.    When you put the diode in the other direction, you must have positive voltage traveling through it.  Positive voltage flows in the opposite direction.

ty i seen this but i was hoping i could get an answer telling me why this works this way, doesnt make sense to me lolmaybe i have been told by u guys, i must not be reading what u guys are writing right lol