It's a bit annoying as even by switching it on every minute it still barely clears anything by the time i get to work as it's only for about 5 or 10 seconds at a time. I found the information about it in the service manual, turns out the solid state timer is built into the relay and that 'timer relay' is in the passenger footwell, attached to the plastic dash. Hopefully Rocky will be able to hook one up, i can swap it out and see the difference. From what i understand there is a resistor and capacitor in the circuit, that's what controls the timing. So when i remove mine, i will try and take it apart and solder new ones in and hopefully that will work. Don't want to take it out as it still kind of works as a back up. Hmm, actually, maybe i can put a temporary switch and relay in. Got a spare relay kicking about that's 30 amps.
Here's the wiring diagrams and info for anyone that will find it useful. If i manage to fix it, i'll post that up too.
p.s didn't know you had a second gen... any pics of it about?
What the hell. I can only assume that over time, they degrade? They are an absolute bar steward to get to... accessing the relay is done by remove the middle panel of the dash - there's the bottom part, which is parallel to the floor and holds the footwell light, the middle piece which is at a 45 degree angle and then the main part of the dash that faces you, with the velcro glove box. It's the middle one that you can unscrew and then see the relay. However, to actually undo the screws that hold it in, it's typical car design: you need to undo the bottom part of the dash to see the screws as they are screwed in from the footwell facing the back. To actually get to those screws (seeing as our arms only have a couple of swivel points) you need to undo the ECM, that's not enough, also unplug it and try it pull it out of the way past a jumble of wires that effectively hold it in place. Finally you can get to the 7mm screws. ugh. Why not just have the screws on the side that the relay is on in the first place. Would mean you dont have to disasemble half of the dash. Or, why not have the relay behind the dash so you don't have to take the front half off. Ugh. Car designs. 
I will look at the wiring diagram tonight and see how i could go about it and what will be needed. Would be nice to keep the existing switch in place. 
