The first step is locating a stock switch, if that is important to you. You could simply wire any old switch in between the antenna signal and make it work by mounting it on a spare switch insert on the dash, but I feel like I want a stock look to my vehicle and to impress people when they realize that it didn't come from the factory like that. If you don't care and just want to wire in a switch there is a tutorial on this site that shows how to do it. If you prefer my type of crazy, continue reading.
Find a junkyard in your area. Preferably one that lets you pick your own parts. Locate a '95-'97 960 or a '98 S/V90. The junkyard I went to had 2 and only one still had the switch. To the immediate left of the steering column, you will see a switch on the dash that resembles an antenna(see pics below). Pry it out and remove the connector. Remove panels or whatever you have to and cut the wiring for the switch as far back as you can. You will thank yourself later. You should try to get around a half foot of extra wiring off the connector. At this time check for any 850s and pull off any parts you need too
. Yoink some LED bulbs from those dash switches too. They come in handy and are expensive at the dealership. The switch with the connector and wiring should be pretty cheap.
- Switch and connector/wires
Looking at the switch connector, we have a red wire in position 4, a red wire with a black stripe in position 3, a black wire in position 5 and a brown wire with a black stripe in position 2. Looking at the wiring diagram for the 960/S90 we can see that the red and red/black wire control the antenna signal. The brown/black wire is the positive rheostat splice and the black is a ground splice. All of this can be easily patched into the radio harness of an 850. If you notice any differences in wire colors or configurations, please reference the wiring diagram for the vehicle you removed the switch from. This tutorial's wire colors and positions only apply to the vehicle I removed my switch from and Volvo is known for switching things up randomly.
After you have acquired a switch and stock harness and are familiar with how it is wired, you should look for a good place to mount it. Since I didn't get quite enough extra wiring, I am going to wire mine as close to the radio as possible. Even though the 960/S90 had it mounted on the left side of the steering wheel, it might make the most sense to mount it in the dash position second from the right. You may have to reroute some existing switches depending on your options. My vehicle came with TRACS, Info, Sunroof, and heated mirrors. This required removing one blank panel and moving everybody to the left one space.
- Switch Positions
- Radio Wiring Schematic
- Switch connections
The Dimmer switch controls a large number of lights inside the car and varies voltage by means of a rheostat slide in the switch. All of these lights connected to the dimmer appear to be in a parallel circuit for power and ground. Were going to access that system too, since it can only improve the "stock" nature of this add on. If you do not wish to, you don't have to do this step. It wont effect the switch. You just won't be able to see it in the dark. I feel comfortable enough in my electrical ability so I'll take the plunge. To be absolutely sure we are accessing the right circuit, take your Voltmeter (Key ON, lights on) and check for voltage at Pin 10A(Pink wire) and 11A (Black wire). These appear on the wiring schematic as (Rheo+) and (Rheo-) respectively. With your DVOM hooked up check the voltage with the dimmer lights all the way down and all the way up. You should see the voltage output go from low (3V) to high (11V) depending on your battery's current state of charge.
- Dimmer Test
- Rheostat hooked up
- Final Product
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