Gauges... its bound to happen

[Black Pheonix]

My gauges are off, at best i can make one or two psi of negative boost, i am 5-6 mph off between the HUD and speedometer (i trust the hud) and my fuel level gauge is at least a half a tank more full than it should be. Can they be repaired?    I am going to assume they don't make new ones for us so if they can't be repaired i will be looking to buy a used one. I hear this is a fairly common problem with grand prixs so maybe you will know.
           Thanks in Advance,

[TGPilot]

Sounds like a ground problem. Do the gauges fluctuate (sp?) when you turn on the lights? I wouldn't know where to begin telling you how to track down a bad ground on our gauge clusters...I have been lucky so far... 8)

[1trucavalier]

no anyone with a n/a dash? if so you could plug there's in to see what the readings are.  Then you can figure if its guage problem or other sensor ground etc......  What about going to the junkyard with your dash taken apart totally with the guage just sitting in there and ask if you can use a n/a for few minutes just for testing.  The jy here are very understanding and would do it in a sec.

[The Burning Rom]

Sorry to bring this old thrad back, but this problem is really bugging me. My boost gauge has to be off...the engine feels like it's pulling around 5 grand..but I can only get the gauge to read 5 psi. I know my speedo is off by 15mph, because the HUD is dead on (I told my dad to drive 55..and I followed him). My gas gauge is off by at least 1/2 a tank (this already caused me to be stranded once). And my tach is screwed too. It seems dead on at idle, but when I get her out on the road and floor it...the needle goes..and keeps going.and going...all the way to where 9,000rpms would be if the gauge would go that high (yes, into the speedometer area). So how can I fix this? I already did the solder joint fix, and that fixed all the dash lights, (except the Anti-Lock light, but I'll post about that later). I just wanna get these gauges reading right! It's hard to diagnose other problems without them :( :( Any input is GREATLY appreciated! Thanks!

Jason

[4PASNU]

Did you try swapping out the instrament cluster as 1trucavalier suggested?  That would tell you right away if it's a problem with the cluster itself or a wiring problem somewhere.  If I had to make an educated guess I'm going to say it's not going to be the cluster itself.  I'm also going to have to agree with TGPilot that it's a good possibility that it's a ground fault.  You could try hooking a test wire between chassis ground somewhere and the ground pin on the cluster.  Good luck.

[The Burning Rom]

Did you try swapping out the instrament cluster as 1trucavalier suggested?  That would tell you right away if it's a problem with the cluster itself or a wiring problem somewhere.  If I had to make an educated guess I'm going to say it's not going to be the cluster itself.  I'm also going to have to agree with TGPilot that it's a good possibility that it's a ground fault.  You could try hooking a test wire between chassis ground somewhere and the ground pin on the cluster.  Good luck.

Thanks for the reply! I have a gauge cluster here from my 90 LE parts car..would that work for testing? Or is the wiring different between that and a TGP dash because of the boost gauge? I have a feeling it's not the gauges, cause they work. And it's not the sensors, because the HUD is correct, so it's probably a ground somewhere, but I want to make sure. I also determined my brake/anti-lock light problem to be a accumulator problem.  :roll:

[4PASNU]

I'm not familiar with what the LE's cluster looks like but from what I understand it should be the same just without the boost.  If that is the case it should just plug right in.  All the signal wires will be the same it's just the Turbo would have that one extra.  I'd try it.

[The Burning Rom]

I'm not familiar with what the LE's cluster looks like but from what I understand it should be the same just without the boost.  If that is the case it should just plug right in.  All the signal wires will be the same it's just the Turbo would have that one extra.  I'd try it.

The LE has a voltmeter in place of the Boost Gauge. That's about the only difference I can see. I have to replace a High-Pressure PS line tomorrow....I'll try it out then.