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1990 Grand Prix LE problem

S

Severoux

New member
I just bought a 1990 Pontiac Grand Prix LE, and it has a problem. The instrument cluster does not work properly... The speedo reads 15mph high when at 30mph and 25mph high when at 40mph. Seems that the higher the speed, the more the speedometer is off. The tachometer shows 3k at idle, when I know its not really that high and it goes far past the red befor shifting( automatic trans). The low fuel indicator light is always on no matter how much fuel it has. The oil pressure and battery voltage gauges always read almost at max. The "Check Gauges" light is always on (duh), and I am pretty sure the trip meter and odometer are off, as in, it says I have gone further than I have.

I have read that the instrument cluster screwing up is a common problem with this year Grand Prix, but is there a way to fix it without replacing the cluster? If there is not... I found a used instrument cluster on ebay that is said to fit the 1990 grand prix. However it does not have a tachometer. Will this effect anything? I prefer to have a tachometer, but I guess I could live without it. Thank you in advance of any help.
 


you can use any 90-93 grand prix cluster

there is a chance that the ground is faulty, its near the obd port next to the radio bezel, you have to remove the piece below the steerign wheel to see it.
 
Found the ground wire that you spoke of, it doesnt look faulty at all, clean wire all the way up to the "shroud" that it goes in to. The screw was loose though, I tightened it but the problems still persist. Any other suggestions perhaps? Or just get the replacement cluster?
 
*UPDATE*

I bought a replacement cluster and installed it yesterday. The gauge problem has pretty much been fixed. The only problem left is the orange Low Fuel Indicator light is still on, regardless of fuel level. Also the Check Gauges Light is still on, which I assume is because of the fuel warning light. Any ideas on what this could be caused by? a Fix? I also bought a Chilton for the car, but cannot find any info on the problem in it...
 
*UPDATE*

The Low fuel indicator light comes and goes, and is often flickering. I believe this to be a connection problem. Once Mother Nature decides I can work on the car without the need of a wet suit, I will trace the wiring from the fuel hanger to the wiring harness in the front of the car and search for anything amiss.
 


Severoux said:
*UPDATE*

The Low fuel indicator light comes and goes, and is often flickering. I believe this to be a connection problem. Once Mother Nature decides I can work on the car without the need of a wet suit, I will trace the wiring from the fuel hanger to the wiring harness in the front of the car and search for anything amiss.
Click to expand...


sounds like a good diagnosis to me :D
 
Hi, Severoux

Have the same problem.. did you find out what the problem was?
Anyone else had the problem, and have the solution?
 
Severoux said:
For the low fuel warning light? No, never figured that one out, sorry...
Click to expand...

No.. sorry, I was unclear, I was thinking of the tacho, and speedo... have the same problem (AND, fuel warning...) Know another guy nearby (in Sweden, that is..) ALSO having the same problem... My car has not (almost) run for 8 years... and now I have the problem!!
 
lasselauda said:
No.. sorry, I was unclear, I was thinking of the tacho, and speedo... have the same problem (AND, fuel warning...) Know another guy nearby (in Sweden, that is..) ALSO having the same problem... My car has not (almost) run for 8 years... and now I have the problem!!
Click to expand...

Yes I did get that problem fixed actually. I replaced the instrument cluster, with a cluster that I found on eBay for $55. The low fuel warning light problem never went away though. I decided that was due to some bad wiring in the gas tank, and I did not want to drop the tank to fix it.
 


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