Electronic humming from alternator

twack · 08-14-2008

I did the saturn alternator swap and have been driving on it for a few days now. Last night i was doing some things and i heard this really faint humming/whine from the alt when the car is OFF. it is always there and is definatly coming from the alt. What is going on? This is with the car off. No codes thrown.

HiImBrian · 08-14-2008

I swapped a motor on a beetle a while back and after everything was done and set there was a humming I thought was from the alternator. Turns out it was just the water pump. If it's not that, I'd double check your wires.

twack · 08-14-2008

This is with the engine OFF not on. Also if i unplug the alt plug it stops

Febo · 08-14-2008

bad altenator?

HiImBrian · 08-14-2008

Quote:

Originally Posted by twack

This is with the engine OFF not on. Also if i unplug the alt plug it stops

ok, if you unplug the alt and it stops that's what it has to be. But, my issue was the same as far as the car being completely off.

twack · 08-14-2008

It does charge

**Kracka** · 08-14-2008

Sounds very odd. Might be worth getting that alternator tested (or just replace it).

twack · 08-14-2008

Ok well i just talked to the guy who made the original write up on this swap and he wrote me:
"The power wire needs to be changed to a switched 12V source."

4g63tcrazy · 08-14-2008

So it's gotta turn on with the key?

Febo · 08-14-2008

easy, just put a relay on the 12v line. Done and done.

4g63tcrazy · 08-14-2008

You sir are very correct.

twack · 08-15-2008

so there is a thick wire, and a plug with 2 wires out of it. which one do i have to do this to

Febo · 08-15-2008

I might be wrong, but Im going to guess you want to find the + source of one of those two wires. The thick one should be the power out for the Alt. and the plug should be the power in wires.