2003 Chevy Blazer will slowly lose electrical power while driving. Battery and alternator tested by auto parts store and check out normal. No corrosion or problems seen with wires to battery or alternator. Charge up battery and ran for about a week without issie but then began again. Now slowly losing power after second start up after charging battery.
Engine stays running even when volts read very low on dash but all electrical components (stereo, dash lights, power windows and locks) will lose power and turn off or work very slowly. Stereo is aftermarket and installed by previous owner (and looks like it was jury rigged to connect when it wasn't designed to). Took out entirely and still having problem.
Is there any known issue with this model losing power like this?
Are there any other places anyone can think to check?
Any help with this would be appreciated and hopefully could help someone else as I haven't seen this issue on any other forum either.
Thanks in advance for any information and help.
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I'd say you've got a bad alternator

 

I agree with the bad alternator - I have had them test ok but replacing has solved the problem.

 

Thank you both. Didn't realize an alternator check can have a false negative. I just replaced it and charged up the battery. Looking good so far.