So that being said, I got a Viper 5901 alarm system for my car last year as a Christmas present from my parents.. A year has gone by and I have not been able to find a shop that I would trust to do a proper job that I would be happy with. So I knew I had to do it myself. Since I have a manual swap, and have watched Pras run his car up a curb and almost into a side of a building showing off his remote start to me and left the car in gear, I decided I really didn’t need a remote start here in southern California. I realize now since im not hooking up the remote start I could have gotten a Viper 3303 which is the same alarm but without remote start and can be found for about $180-$200.
So after downloading every wiring guide I could find, including the DEI one, the Volvo one, 2 more from the 12volt.com, and the Hayes manual. I set out to find the wires that I have to hook up. And because no one of these guides makes it easy for you to figure out what wires to tap, and because I had to trace these wires out on every diagram, I am now going to make an easy write up for how to install a basic alarm better than any alarm shop could even do it by tapping only one wire and soldering it instead of crimp connectors. Done right this will last the lifetime of the vehicle. However you should always test the wire colors I provided with a meter first before tapping them to ensure they are correct. I assume no responsibility for any damage caused due to these instructions. I am however, 100% sure of their accuracy for 1996 850s.
However for my security I am not going to show almost any pictures because I don’t want people to know where I installed it in my car. But I am going to tell you exactly what wires to tap to get parking light flash, lock/unlock, door sensor, trunk sensor, hood sensor, tilt sensor, and glass break sensor.
You will need
- quality solder 60% tin/ 40% lead .8mm diameter with a rosin core. NO that stuff you has left over from sweating the water pipes will not do in this application LOL.
- High quality solder iron
- 3m Super 33+ electrical tape 66ft roll about $5-6 each
- 4", 8" black zip ties
- Digital Multimeter
- wire loom in 1/4" and 3/4" sizes
- wire fishing tool, generic wire hanger will do most of the time or I used solid core copper wires (very stiff)
Wire Location
12+volt constant Input (+) Tap any red wire with 12+volts constant (Most red wires)
Ground (-) Tap any black wire
Siren Output (+) Goes to the siren under your hood/ wiper cowl. I put mine under my wiper cowl, just remember to face it slightly down so water doesn’t collect in it.
Trunk Pin trigger Input (-) Red block, Red connector, pin 11, blue-brown wire
Instant trigger Input (-) Some alarms can have multiple triggers from other things such as backup batteries that instantly trigger the alarm, mine shared this trigger with the trunk pin
Door Trigger Input (-) Red block, Blue plug, Pin 6, Yellow-White wire
Parking Light Output (+) Yellow block, Blue plug, Pin 8, White wire
Unlock Output (-) White block, Blue plug, Pin 8, Blue-Brown wire (This wire must be double pulsed to unlock the car, I had to set that in my alarm settings)
Lock Output (-) White block, Blue plug, Pin 10, Yellow-Grey wire
Hood Pin Goes to a hood pin you install under the hood, here Is the custom mount I did for mine Here are some pics of the bracket I made:


You will also have to run wires up to you dome light for the controller antenna where you can hide the module in there. I attached it to my ceiling above my passenger side of the dome light.


Of course all my connections are soldered and heat shrunk on. I pulled each pin out one by one and used a razor to cut away the wire insulation and wrapped the alarm wire around the Volvo wire and soldered it, then slipped a piece of head shrink on the end, lighter and reinstall the pin into the plug. Here are some pics of after I was done:





I also bought a glass break sensor module and 2 window modules that I will be getting next week so that I can add them onto this write up for those that want to roll their windows up as they get out of their cars. They also add 1 touch to every window.
Hopefully this guide will help those people out on the fence about doing it themselves.

























