All of these things have the charging system in common, and on GM cars and trucks that is a very high-failure system. The generator should be professionally load-tested for maximum current and "ripple". If one of the six internal diodes is defective ripple will be very high and the most current you will get will be exactly one third of the unit's rating. For the common 90 amp generator that means 30 amps, and that is not enough to run the entire electrical system under all conditions. The battery will have to make up the difference. As it does, it's voltage will drop. Computers are very intolerant of low system voltage and will shut down or do weird things. The result is a lot of warning lights turning on.
It is common to go through four to six replacement generators in the life of the car. To reduce the number of repeat failures, replace the battery at the same time unless it is less than about two years old. As they age they lose their ability to dampen and absorb the huge voltage spikes these generators produce. Those are what destroys the generator's internal diodes and voltage regulator and cause the repeat failures.
Tuesday, May 14th, 2013 AT 12:43 AM