My HUD has lost its brightness. I used to be able to see it very clear during the day, but now I can barely see it unless it is dark out. (yes, I have turned the brightness **** up).

Can anything be done about this?

This could be a few different problems and may require having your car scanned for codes.

1. The HUD projector module is defective.
2. The HUD intensity control and/or wiring to/from this control may be bad.
3. The sunload sensor on your dash may be bad.

To have your car scanned, it will have to be with a Tech 2, not an aftermarket scanner. Some of the possible suspects can't be accessed without the actual GM software. The sunload sensor adjusts day/night and can influence the brightness of the display.

Does the intensity change at all with the control?

Yes. If I turn the brightness down, it will get dimmer.

If your intensity does change with control movement, it isn't likely the control is the culprit. Have you noticed any differences with your exterior (park) or dash lights? For example, do you notice them being on during the day when you wouldn't otherwise expect them to be?

There is a cold solder joint on the HUD that breaks after a while. This causes the HUD to always show nighttime brightness (which isn't bright in the daytime). I'll have to find the instructions on how to resolder it.

I remember seeing this on Club GP. Not sure if it would be the exact same fix, but definately some very good information.
http://www.clubgp.com/newforum/tm.as...anguage=single

This is certainly possible but before taking apart the HUD, I'd recommend checking the other exterior lighting. If it is functioning normally then pull apart the HUD. If it'* not, the problem may well be elsewhere. I believe it'* generally better to start with the easy to rule out possibilities before disassembling modules.

In addition to the cadmium sulfide photocell in the HUD, a message is also transmitted over the class 2 serial data bus indicating day/night status. This message is broadcast either from the Instrument Panel Integration Module (IPM) or the HVAC control head depending on what type of climate control the car is equipped with.

That post on the GP forum does look like it could be very helpful, if it comes to this.

Sorry, I had to go out of town and could not check anything. I am going to try to check the brightness of the dash lights when it gets dark outside, versus the brightness when it is light out. I will let you know what I find.

When I cover up the light sensor on the dash, the dash lights, parking lights and head lights come on, but there is no change in the brightness of the HUD. Normally, the HUD brightness should get dimmer when the dash, parking and head lights come on. So, it looks like the HUD always thinks its dark outside.

I guess I need to pull apart the HUD. Am I correct?

If so, how the Heck do you get to the HUD. Do I have to taKe the dash apart?

Sounds like that is probably your next step. With a Tech 2 there are a couple of other diagnostics and/or tests, but probably easier to move onto the next most likely suspect.

To get the HUD out, you'll need to remove several parts.

1. 'A' pillar trim, left & right.
2. Defrost vents, left & right.
3. Sun load sensor (rotates 1/4 turn to remove from the defrost grill).
4. Instrument cluster trim.
5. Trim panels on each end of dash (w/ rubber vents to carry defrost out to the doors). These just unsnap. Start at the edge closest to the REAR of the car.
6. Screws holding the dash pad in place.
7. Dash pad itself.
8. HUD connector.
9. Screws retaining HUD module into the dash.

Hopefully this helps. If I can find a diagram of the screws holding the dash pad in place, I'll post it. I know there are some underneath the defrost grills, some behind the instrument panel trim above the speedo cluster and IIRC one at the end covered by one of the side defrost ducts (carrying air to the door panels).

As a matter of safety, it is a really good idea to disarm the SIR system. New information states you should only need to pull the fuse. Always use caution working around these components. If you are not completely comfortable with this, I would recommend taking your car to a service facility.