Question, if a good external regulator got paired with a bad alternator would it screw up the good regulator?

 

it could

depending just what the problem is.

So many kinds of bad alternators to choose from.

My question is just what happened and what is it doing now??

 

Okay so purchased a new to me truck, guy put in a new alternator but not a new voltage reg.. brake and battery light stay on. So I purchased a new voltage reg without thinking they should be switched together but I switched it and lights still stay on. Couple days later radio turned off while driving, blinker dimmed lights had to stop and get gas :/ completely dead. Anyway so then I ended up getting a new battery needed one anyway had the starter tested passed, then put the new battery in and went and had the alt tested and they said it wasn't putting out and running off the battery so now I have a new alt (not installed) and a newer voltage regulator that was paired with a bad alternator.

 

all three (battery, alternator, external regulator) go hand in hand, if one screws up the rest get fried. i had a voltage drop in the power going to my external regulator which caused an over charging condition, which killed the battery, which then killed the alternator. test each piece of that puzzle and make sure they are good before installing them.

its possible that your regulator is still good though. once you install the alternator, check to make sure you are getting around 14v +/- .5v to the battery.

 

But if the regulator isn't good, do i run the risk of ruining a new alternator?

 

only if you run it for long periods. it'll be ok just to test it. the reason my alternator died was because it worked HARD to charge a dead battery.

this happened on my dodge truck by the way, but it all works the same. i had to rewire a lot of stuff to get the charging system working properly again. i've messed with this stuff quite a bit.

 

you know how to test to see if the voltage regulator is bad or not huh?

 

it is possible to test the voltage regulator out of the vehicle.

If you have the FSM for your year truck.:jessica:

 

Okay thank you for all replies.. Went out and bought me a multimeter idk why I never owned one. But got it all worked out battery light and brake light both stay off and battery idles at 14.2 on the meter.. Plus the man I bought it from put the wrong alternator in it! That's way the lights were on in the first place! It was a "B" series alt and I needed a "A" series, simple as that. Blah! Now to fix my idle issue.

 

yep i own 2, expensive one for the garage and a cheap one i keep in my truck. sometimes i like to help people with my cheap multimeter