How To Test an Alternator
Submitted by tommytomato on Thu, 2010-09-09 07:40
Hi all
How To Test an Alternator how do I do it
I put on a muti meter and it reads around 12.43 when not running, when it is running volts are dropping.
I run the 4x4 and took the red lead off and 4x4 stopped, is that how you do it, its been some time since I've had to test an Alternator
some one care to explain please
TT ( karl )
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Dicey
Posts: 912
Date Joined: 23/07/10
get voltage rating when
get voltage rating when engine isnt running, start the car take voltage again, now get someone to rev the engine, if it shoots past 13 volts then alternator is fine, but the way you described it sounds like it is buggered.
just dhu it
Posts: 1081
Date Joined: 14/05/09
put load on
as said before , measure the voltage first with motor not running, approx 12 to 12.6 is good , start motor and measure again , some alternators dont charge until loading or revs are increased, best to set revs at 1500 rpm and turn on your head lights and the alternator should put out 13.4 plus volts
Brucesta
Posts: 1721
Date Joined: 29/05/09
as they said, look for the
as they said, look for the difference under load and running, definantly sounds like it's cactus if the volts are dropping
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wide open
Posts: 444
Date Joined: 24/12/09
there are many
there are many vids on youtube how to test a alternator
is ur battery going flat or somthing whats wrong
mark hayes
Posts: 6
Date Joined: 27/06/10
connect your multi meter to
connect your multi meter to the back of the alternator positive {main cable} and the other lead to the battery negitive start the vehicle and lift revs 13.5v will be ok a good alternator will charge at 14.2v
also load test your battery connect meter to negitive and positive and crank motor batery voltage should not drop below 9v if it dose replace battery
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Goatch
Posts: 1011
Date Joined: 03/07/07
Also ,
I seriously don't recommend pulling any battery leads off any car while the engine is running , it can have a couple of outcomes , fried ECM comes to mind , battery explosion is another that I have seen over the years also if the alternator isn't cactus it can be afterwards I guess the only thing it can do on the odd occasion is re-excite the charge circuit but that will be only temporary.
Just one more cast , honest !!!