when im driving my blazer at around 2100 rpm my volts go way down and everything goes dim. i already had alternator checked out and it passed 3 times. any ideas?

1997 2 door 4WD it have a K&N air intake system

 

Please tell us a little more info about your Blazer so we can further help you.. what year is it, 4wd or 2wd etc

 

x2. We need more info. You can't expect us to troubleshoot without ANY information regarding your vehicle.
Just a tip...post up the info about your vehicle in your sig. Year, model, mods etc. will help us to help you.

 

sorry about that i edited the information thank you for your time

 

How long does this last? What other conditions is your truck undergoing? Acceleration? Deceleration? Are you turning on any accessories? Turning right or left? ETC...

 

any time over 2100 rpms it happens untill rpms goes under 2100

 

It definitely sounds like something is amiss with the alternator and/or its wiring.

 

Have you tried to pop the hood and rev it slowly and see if it still does it without driving it, that way you can listen and see if the alternator is whining, etc.. you may be able to hear if anything is abnormal... you may also want to check the wires coming off the alternator

 

what could be wrong with the wires

 

Grounding out. Broken inside the insulation. Anything that could be vibration or otherwise related to how/when the problem occurs.