I have a 94 power stroke when I turn the ignition the glow plug switch clicks open, but they don't start to click back and forth until the engine starts. On my 93 the glow plug switch clicks open until wts light goes off and then they click on and off. So is there something wrong with my 94? The reason I ask is it is really hard to start when its cold.

 

The glow plug system in power strokes is a little diffrent than one on a idi. On power strokes the wait to start light is really just a dummy. The glow plug stay on long after that light shuts off. For up around 2 min. If you are have problems during cold start you might be having problems with the glow plug relay or you have some bad glow plugs. If you have a multimeter you can test this system pretty easy.

 

I have replaced all 8 glow plugs and the relay

 

Un plug the pig tails at the valve covers and look for burnt pins. If they are all good, use the multimeter and ohm through the valve covers to see he the harness under the valve cover is fried.