Thread: How to fix 91' HUD, non-dim issue

Difficulty: Moderately Easy
Time Needed: 30 minutes or less

This is to repair the HUD unit on a 1991 Pontiac Grand Prix and similar models.

This issue is not related to a random "dim" or "ghostly" effect on the HUD projection. This was an alternate problem that I had discovered.

There are two mirrors on the inside of the unit. One is at a fixed position and the other one is adjustable by the HUD Adjuster on the right hand control panel located by the HUD Dimmer.

The mirror that is adjustable is fixed on a plastic ball-joint. The female end which connects to the adjustable mirror itself somehow popped loose after the numerous accidents this vehicle had prior to my ownership of it. At the time, I did not know this to be the issue and I assumed that I had an issue with a bad factory solder that goes on the mainboard, which is the typical issue today. This may apply to some of you that smacked a storm drain or went over a hard bump and the unit stopped working. Let's get started:

1. Finda torx screwdriver and a 7mm socket or screwdriver bit
2. remove the two 7mm screws underneath the dash infront of the instrument cluster
3. lift the HUD unit and disconnect the wire harness. This requires a bit of wiggling and you
   should be at a good angle to get it out. Depending on your angle, you may or may not get it out easy. There is a blue tab to squeeze as you are removing it from the unit.
4. Place the unit on a table or somewhere sturdy, I put it on my lap, and remove the four torx screws that hold the assembly together.
5. Depending on the condition of the plastic ball-joint, you can simply pop it back together. Otherwise, you have a bigger problem and it either requires jury-rigging or a trip to the junkyard.
6. Clean the mirrors. This is common sense. You want the unit to work at it's best ability.
7. Reassemble the unit, plug it in, and place it back into it's crib. Make sure the tooth on the adjuster meets the plastic fitting on the HUD Adjuster cable.
8. Turn the key and try moving your head around, if you see the digits, you solved your problem. Try moving the adjuster after you screw the 7mm screws in to make sure the teeth lined up.
   
   
   I hope this helps. If pictures are needed that is no problem.

Sounds like a solid fix to me. Thankyou for your input.

I will most likely remove this then. But the HUDs are different in generations. Especially removing them from the dash. So i'm having second thoughts. Keep it or lose it?