alternator check
 

I would normally check a altenator by disconnecting the hot bat. cable while the engine is running. Does anyone know if this action would cause damage to the alternator?? Thanks in advance for any input marvxyz1

Re: alternator check
 

That "test" is not a valid one, IMO. Borrow or get a VOM & just read the output voltage. The gauge inside the truck should indicate weather or not the alternator is working, also.

Re: alternator check
 

We all have ways to do things. I usually just put a piece of metal against the back of the alternator (center shaft cover) and see if there is a magnetic field being generated. My pocket knife works well for this. That tells you if your alternator is making an electrical field. Second, use the VOM to check for voltage to the battery and see what you are getting. The voltage should be around 13.5 volts or more.

Re: alternator check
 

Disconnecting the battery cable while the engine is running can,will & does cause a voltage spike for just a milisecond (18v - 36k volts) as witnessed by the tell-tale "spark". On older, precomputer controlled vehicles this isn't a real big problem. But on the newer vehicles it can fry out your PCM. I wouldn't recommend doing it on any vehicle regardless of age just for safe practice.

Re: alternator check
 

Turns out, that the vehicle in question problem was slightly untightened pos. cable clamp and the clamps were a little corroded. This was the no-start reason. I do thank you all for the onfo., which I wasn't sure of..
marvxyz1

Re: alternator check
 

I do it the lazy way I take mine to the local auto part store and have them put their meter on it to check it and the battery

Re: alternator check
 

My question to you is.................

Why are you checking the alternator?

Did you have a not start situation?
Is it not charging?
Is it cranking slowly?
Did you add anything aftermarket to it?

There are many different ways to check an alternator, some are more accurate than others.....

First I would check the output voltage, by checking the voltage across the battery terminals, this should be anywhere from 13.5v-14.5v for a normal alternator, with radio, headlights, turnsignal, and heater on high.

There are about 4-5 steps to accuratly check a charging system

Just my 2 cents
Duro

Re: alternator check
 

Sorry I just read this after I posted............I was just skimming over the post

Duro