So my 97 4wd 4.3 Blazer has been plagued with a bunch of random problems, I saw in another thread that some people were having issues because of the alternator. I put my voltmeter on the alternator to check and only got .2v ac, 14.6v dc, everything looked good. I figured I'd try running it without the alternator to see if it made a difference anyhow, but when I run without the alternator (by either unplugging the plug that goes to the ECU or by removing the positive wires from the bolt on the back) the car runs super rough, misfires and stalls. Any ideas what would be causing this? Is it a clue to my many issues or do these trucks just not like running without an alternator?

 

By far not an expert, but when my alternator was dying everything electrical quickly failed. 100 feet down the road the radio turned off, then the lights, and finally the engine turned off. If I had to guess I'd say you need an alternator to run the car.

Based on my understanding the only electricity coming into the engine is now from a quickly dying battery, good luck keeping it running on a battery that just used most of its juice starting the car. Not an expert though, just my experience.

 

Alt charges battery, battery runs car. simple

 

What is th voltage on the battery when the truck rund rough without the alternator?

George

 

I am not sure that I really understand why your alternator would cause any issues. Car systems run on DC not AC. If you are getting 14.6 DC volts you are good. Without the alternator to charge the battery you won't be able to run very long.