If your battery is more than few years old, replace it. There is no kind way to say it, these generators are quite the pile, design-wise. It is common to go through four to six in the life of the vehicle. What more and more professionals are finding out is to reduce repeat failures, you must replace the perfectly good battery at the same time. It will work fine in pre-1987 vehicles, but as they age, they lose their ability to absorb voltage spikes. GM generators, because of their design, produce a pile of voltage spikes that interfere with the sensor signals for the many unnecessary, complicated, unreliable computers on the vehicle.
When you replace the battery, be sure the cable connections are perfectly clean and tight. If the problems still continue, replace the generator again.
Saturday, December 4th, 2010 AT 7:59 PM