No, but if it is computer controlled, it is the computer that will do weird things, then shut down. All computers become confused when system voltage is low. Once the generator fails, if you had started with a fully-charged battery, you will get about a half hour of driving on just the battery before it runs down. The more high current items you use, like the heater fan, head lights, wipers, etc., the less time you will have before the battery is too weak to keep the electrical system going.
Beginning with 1987 models, GM has had a lot of generator failures. Repeat failures are also very common, but the way to reduce that number of failures is what you already did, that is to replace the battery at the same time unless it is less than about two years old. Due to their design, these generators develop a lot of voltage spikes that can damage the voltage regulator, and interfere with computer sensor signals. The battery absorbs and dampens those spikes, but as they age and the lead flakes off the plates, they lose their ability to do that.
Charging the battery proved everything else is okay since the engine started normally. Use an inexpensive digital voltmeter to measure the battery's voltage when the engine is running. If the charging system is working, it will be between 13.75 and 14.75 volts. If you find that, it only means it is okay to do the rest of the tests, but that requires a professional load tester. In particular, we want to know "full load output current", and "ripple voltage". Those will tell us if all of the generator's internal diodes are okay. If one of the six has failed, you will only be able to get exactly one third of the generator's rated current. A common GM generator is their 90-amp unit. 30 amps from it is not enough to meet the demands of the entire electrical system under all conditions. The battery will have to make up the difference until it slowly runs down.
Here is an article that further explains testing the charging system:
https://www.2carpros.com/articles/how-to-check-a-car-alternator
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Friday, May 11th, 2018 AT 12:21 PM
