HUD Different Problem

[muskrat]

I have searched a few times and read about the HUD, but the problems that others have seem to be different from mine.

I have a 1992 240SX SE. When I turn on the car my HUD comes up "0 MPH" on the dash and "0" on the windshield. It will stay on for 2-5 seconds then fade out. It will never turn back on, not while I am driving, not when it warms up, not when I turn on other things(headlights, wipers, etc...).

If I am going down the road I can push in the clutch, turn off the car and turn it back on and the digital speedo and HUD will appear for 2-5 seconds (just like when I start the car) and it will show my speed, so I know that the thing is working it is just not displaying. Everything else on my dash works.

Any ideas for me?

I have a 1993 digital dash and HUD unit out of a junkyard car, but I don't wanna swap that in and find the same problem, I'd rather exhaust fixing this one first.