99 civic defogger

Car is a 99 Civic and the alarm/rs is a Viper 5900. I installed it myself, everything works fine. Only snag is how to trigger the rear defogger. I'm a little confused searching for help and figured I'd better just ask. The H3/5 blue/white wire can be used to trigger the rear defogged but it's a negative output and I see posts saying to activate the rear defogger it's a positive input. Or tap the wire in the blue connector. And I'm all confused and hesitant to do anything without knowing exactly what I'm doing and it's probably as simple as hooking the blue white wire to one of the wires off the switch in the dash. So I guess my question is how do I hook up the defogger to the rs?

If you use the search box you should find many questions about connecting rear window defroster. In most cases you will need a relay. Here is a link to a recent query:   https://www.the12volt.com/installbay/forum_posts.asp?tid=124573&KW=howie+ll

I connected my son's 1998 Cavalier using a relay. Had to find the wire going to the rear window, cut it. Switch side of wire to 87a, windowside to 30, Ignition 12 volts to 86, Acc 12 volts to 87, and the defrost wire from the brain to 85.

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Above the fuse box is a long skinny blue plug. Find a blue / YELLOW there, it's a (POS)+ needs to be latched.

I tapped into the trigger wire behind the HVAC controls. Can't remember what wire, but basically it triggered the rear defog relay, so I didn't have to install another relay. I just used a trigger to trigger another trigger.