Digital Speedometer Issues

[devilleconcours100]

Hey, I am looking at a 86 Cimarron, because all of my V8 cars are killing me on mileage, and the Cimmy has a V6. The car runs good and has low miles, and is pretty cheap, but there are two problems. 1. The dash will say 60 when you are going 72, and 2. The power windows and Radio both don't work. I am thinking a grounding problem, but please advise.
Thanks, Dave

[stevehogan]

The first thing I would do with a car that old is to verify that it is ABSOULTELY running the original-size tires and wheels. The number 1 cause of messed up speedo readings is a tire/wheel size change. For example. If someone put 1 inch larger wheels on the car, it would account for that kind of speedo difference.

[bengsxr]

umm no the first thing is don't buy it unless you are prepared for alot of headaches. cause you want to save money by driving it well go buy a little four banger that get 30 mpg and alot less of a headache.

[ahanash]

I have disconnected the battery on my car to replace the ISC motor, after I conncted the battery back and drove a little bit, I had 11 gal of fuel, and MPG of 16, but the driving range was like 94, I did perform the TP learning procedue, is there another thing needs to be done? the driving range should be 11x16 or changes according to the MPG? any ideas?

[devilleconcours100]

The car seems to run good. The guy bought if from an auto auction in Virginia, and drove it home. The oil pressure light is on and the gauge says 0 Oil Pressure, but I testdrove it about 15 miles and I assume that the engine would have locked up if it had 0 Oil pressure. I talked to the local Cadillac Dealership, and they said that the sending unit was probably bad, and said a new GM one was about 15.00. Also the mileage said error, and I am thinking that the whole dash is probably shot. I know it sounds like a lot of problems, but you have to remember the car is DIRT CHEAP.
Thanks, Dave