the short is visible in the tire pressure light and the battery light. They flash when bumps in the road are hit? How are these related? and what typeof shop could repair this? Is it an expensive fix or are they generally easy to find?
Problems like that can be extremely difficult and frustrating to find, especially if it can't be made to actup while sitting in the shop. It's impossible to drive a car safely and try to search for causes at the same time.
GM has a real lot of trouble with their generators since the '87 model year. Abroken or corroded connection going to it can cause the battery warning light to turn on intermittently. When the generator stops working, system voltage will drop momentarily. Your car is full of manyunnecessary, unreliable, complicated computers that are very sensitive to system voltage, so it's common for them to act up when the generator stops working. It's real common to read that someone'santi-lock brake warning light turns on at the same time, but any of a number of systems on the car can be affected.
The tire pressure monitoring system also uses a computer, and, both the generator andthe computers get their power through one part of the ignition switch. An intermittent connection inside the switch or in any wire related to it can cause intermittent connections over bumps.
GMhas done a real good job of preventing independent shops from working on their cars so you're sort of tied to the dealer for problems like this. If you have an independent shop in your area thatspecializes in auto electrical, they should also be able to find the problem. Plan on leaving the car with them for at least a few days. Unless they find something real quickly, they'll have to searchbehind the instrument cluster and under the hood, then perform a number of test drives to verify the problem is solved. Larger cities have many specialty shops that just work on electrical problems....