I had a 1987 Nissan Sentra with the same problem. There is a chip on the backside of the instrument panel which failed. I got one from a junkyard and installed it and that fixed the problem. It is pretty easy to remove the instrument cluster, but there are a lot of screws. If you have a pick-and-pull type of junk yard you can practice on the junk car that you are pulling the chip from. If I remember correctly, you also have to remove the steering column cowling as well. Again, just a lot of screws and you might need a long phillips screwdriver to get deep into the screw well. I think the chip is mounted on a piece of plastic and you can just unscrew it from the back of the old panel and unplug it.