2003 Sierra Speedometer/Oil Pressure Problem

I've got problem with my Sierra speedometer and now oil pressure gauge. About 2-weeks ago the speedometer starting sticking indicating random mph readings. When doing 40 it might indicate 90 or 100 mph. When stopped it would sometimes indicate 40-50 mph. By hapstance I found that while stopped I could shutoff the engine and re-start the gauge would incremently drop app. 10-mph, by doing this several times I could get it finally reach zero.
This "sticking" was random, but seemed worse as the weather got colder up here in PA.
Then yesterday on the way into work I noticed the oil pressure gauge was wrapped completely pegged (extreme high pressure). It did not decrease by restarting, but finally returned to normal while the speedometer was reading normal. This morning it was doing the same as I was by the speedometer travelling 120+ mph (really about 40).

Any ideas? It makes me think its computer related as both problems seem to happen during at the same time.

The truck has a 4.8L V8, manual 5-speed, and app. 25,000 miles.

I have a 2003 Sierra 2500HD w/ a Duramax diesel. My entire gauge cluster has just begun working intermitently.... The first time I start the truck in the morning the gauges do not activate. The second time I start the truck they will work normally.

Just today (first time) the gauges have not worked at all no matter how many times I've started the truck. I checked the fuse block under the hood and the fuse that's indicated as related to instruments is fine?? Has anyone else experienced this type of behavior?

It has been unseasonably cold here as well.

Art

Art,
My oil pressure is now reading OK, but the speedometer points to the odometer, wound tight, even after turning the key off.

I have a 2003 2500hd 6.0LT with 12,000klms and had the cluster replaced under warranty apparantly its a problem. My battery light would stay on took it in they said they had to replace cluster works fine now??

Thanks 03GMC,

I'm going to check the under-body ground connection to assure its making good contact, but I'm afraid my 03 will re-visit the dealer also.

I have a 2004 GMC Sierra 5.3L 4x4 Auto and it does the exact same thing as the original post. Usually when it rains. I have found several others with the same problem. Since it corrects itself by 10 MPH by restarting the car, the problem is usually gone a week after it happens. I have never made it to the dealer in time to show them. I am going to look at the connection to the tranny tonight thinking maybe it has a loose rubber gromet and water causes an intermittent contact. I just don't want GM to swap my dash and find out in a month that the problem is still there.