I just picked up a FRC and it has HUD installed. The fellow I bought it from did say it wasn't working properly so I have been playing with it. It doesn't appear to be displaying anything or even working for that matter. When I slide the switch from off to on the dash lights dim, but nothing comes from the HUD unit.

What could be wrong?

UPDATE: The HUD will display when the headlights are off, BUT, you can't adjust the settings at all and the dash and DIC still dim when you try too. Once you turn the headlights on the HUD disappears.

LOL, this is weird.

 

The dash lights dim? All of them, or just the main gauges (IPC)?

If it's causing the other lights to dim I'd say the HUD unit is not connected properly or it's kaput.

Tim

 

either connector isn't seated properly or you need to check continuity.

 

The HUD connects via a small connector on the top rear of of the IP Cluster. If that connector fell off, there's your problem.

 

See Update in original post... Thanks.

 

Evening bump.

 

Ok, re-read your updated post. You say when you slide the intensity slider, the dash lights dim? Its not suppose to have anything to do with the dash lights, only the hud itself. The round **** is for the dash lights.
The dash lights are controlled from two different sources depending on the options. If you have a twilight sentinel, there is a light sensor on top of the dash. If its turned on in the DIC programming options, it will cause the headlamps to come on and up, dim the dash and control the dash illumination from the round ****.. When its day time outside, the dash indicators such as the DIC and HVAC display are controlled by a small light sensor which is in the top of the DIC Controller on the right side of the IP Cluster.
Back to the HUD, it has its own light sensor. You can see it from the outside at the top edge facing backwards toward the rear of the car in a small hole there. It controls the main HUD brightness and the slider control is basically an override to it or lets say a fine tuning.
Now this is all for a HUD equipped car. Now if your's didn't come that way, maybe something was left out although I don't have a clue what. It bothers me that the HUD brightness slider is causing your dash lights to dim... that should not happen. Was this HUD added after the fact?

 

How can I verify if this was an orginally HUD equiped car? It's a 99 FRC.

I'm thinking something is wired incorrectly, because the slider does in fact dim the dash when moved.

 

Do you have the small round **** just below where the slider is? What does it do when you adjust it...note that you push in to let it pop out to be able to do that. Both of those controls, the slider and dimmer are on the same unit which attaches to the IP Cluster. I don't know the RPO Code for the HUD but someone here will know it and advise you. All of the factory installed RPO codes are listed in the glove box.
Back to the wiring, its next to impossible to alter it since it connects directly to the IP Cluster. I'm starting to wonder if you lost a ground somewhere. I think a PM to Bill Curlee is in order for this. I gave away my '99 Coupe to my son in May, so I don't have it any more to run things down.
Have you pulled the codes yet? Checked all the fuses?

 

If the HUD was added by a previous owner and was not original, there is a possibility that the wiring harness between the HUD and the IP cluster is incorrect. Determine whether the HUD is original by checking the RPO codes.

 

I'll check the codes and get back to you guys ASAP.