glow plugs? Relay Maybe?

I have a 1993 Volkswagen Passat TD We have a Glow Plug Problem, They won't glow up unless you manually make the contacts ( of the relay ) come together, then they'll light up and the car starts no problem! I've changed the Relay (#104 in the 12th position) , and still no such luck. I've had a buddy with some electrical know how come and look at it, but Didn't get much accomplished. Also the glow plug light doesn't come on anymore. and I've had the dash apart, and the light still works! This is what the prongs look like, for somebody who doesn't know. There are 2 BIG prongs, the one has power to it at all times, and when the contacts come together, the power flows through to the other BIG prong, making the glow plugs glow. Now!! There is a MEDIUM sized prong, and supposedly this is a positive lead. When the ignition is off, there is no power there. When the ignition is on, and the car is running the is power there, I've had the car heated up to normal running temp. and there's still power there. There is also a SMALL prong, which is supposed to be a ground. I NEED HELP WITH THIS!!! WHAT SHOULD I LOOK AT NEXT!?!?!?!

Thanks

Ritzi

I THINK the glow plug relay contains a timer, and the length of time interval that the glow plugs remain energized is controlled by a temperature sensor on the engine, perhaps connected to that mysterious fourth pin. Could check with somebody who knows about that sensor and wiring connector. Another weird thing is that circuit boards in relays can be damaged by water, usually on fuse boxes mounted on a forward slant. good luck rich