i got a 91 pickup 22re and when I have the lights on and apply the brakes the battery meter goes to almost none and theres a small squeal. wondering on what this might be

 

alternator?

 

That's what I was thinkin but I don't know where the squeal would e comin from and why it ony does it when my lights are on... Oh and the brake light has stayed on since it started

 

yes most likely alternator.

 

try checking the alt. belt ,it sounds like it is loose or wore out. when you put enough load on the alt. the belt might be slipping .

 

x2 on the alternator, but could also possibly be battery, a bad ground, corroded connection, or a corroded wire.

If you find it to be a bad alternator, make sure the battery has a full charge before firing it up for the first time once you have replaced/repaired the alt.

 

this helped with my voltage drop allot..

https://www.yotatech.com/forums/f116...er+supply+wire

 

basically, it's all pointing to your alternator. When you brake, your rpm's drop, in turn not spinning your alternator enough to create enough power. It could be a couple of things, your belt could be old, your alternator could be bad or your voltage regulator could be going out (I'm not sure if they're integrated into the alt. on yota's or not). Do you have any extra electronics in your truck that pulls directly from the battery, say maybe an amp to a sub or anything? If you do, you may want to install a capacitor in the power line. Either way, your alternator isn't getting enough spin to give you ample power. Check your belts first since that's the easiest and cheapest fix. After that, I'd say run your truck for about 20 minutes and then disconnect the positive battery cable. If it dies, your alternator is donzo.

 

I don't recommend disconnecting the battery when the vehicle is running. It acts as a very necessary capacitor itself, kind of like a surge protector. At least, that is what we were taught in school, and it makes sense to me. Everything else sounds good though.

 

^indeed, NEVER disconnect the battery when the engine is running.

Secondly, never recommend capacitors to help with voltage drop. Fix the problem and you won't need a band aid.

 

Put LED brake lights in

 

This happened to my '86 the other day. Turns out my battery was loose and when I braked the battery would lurch forward and disconnect. Then lean back and reconnect... didn't learn this until I tore already took the alternator off just about and noticed that the wire was loose on the battery. Life's tough.