Anyone used a windows program called ProScan? The software comes with a serial interface and the company alledges it will read the codes and is able to reset the maintenace service light.

You need a special Volvo tool to reset the Service light. I have a code reader and that can reset the CEL but not the service light. Usually, the dealer will do for free next time your there. Or be like me, and leave it on forever. I'm just gonna take the bulb out, since the light is meaningless anyways. I don't need a light to tell me make car needs simple mainaince.

Where do you plug in a OBD2 scanner on a 1996 850T , I cannot find the plug and my check engine light is on???

I have found the plug in point. It is located in the centre console just in front of the gear lever under a 'faux' ashtray.Now how do you reset the 'service engine soon' light?

If you want to reset the service light, you'll need to go to the dealer or buy this.
http://ipdusa.com/ProductsCat.aspx?CategoryID=519&NodeID=178&RootID=629
This light comes on just to tell you to get a check up at the dealer after a certain amount of miles. It doesn't mean anything bad. I do my own work, so my light will be on forever.

The Check Engine Light is something different. That means you threw a code. I bought an OBDII code reader and you can reset it with that. Places like Autozone and Napa will read them for free, if you don't want to spend the money.

thanks for the help, yep I have an OBD 2 scanner and it is worth every penny. My problem was a bad coolant sensor in the overflow bottle.

Yeah, that's a common problem. Same thing happened to my brother's S70.