How to check an alternator

Post by **Linda** » Tue Jan 31, 2006 2:02 am

Vihn,
On your alt next to the screw connection ( should be the one closest to the outer part of the alt) you will see an "E" which is for Earth or Ground. Should be a wire from here to the frame, usually black, look for a hole near the vin numbers on your frame right next to the alt for it to attach to frame. You will likely have to make this wire.
On the inner side of the alt (closest to engine) is a stud with a nut and next to it are the letters "Bat" or "B" for Battery, This is for the hot wire. Then there is a plug coming out of the alt with 4 wires in it to plug into your harness plug. The colors should match.
So, get that ground wire going first , then the "battery" wire which is the heavy white wire.
Hope this helps
Linda
68 1600

Post by **ppeters914** » Tue Jan 31, 2006 5:04 pm

Well, well, guess Linda was faster, however, her link only takes me to the "Join Webshots and your life will be wonderful" page.

So, my turn...

I posted several pics in the General Category of the 311s.org Photo Album. Unfortunately, pics in the album don't display (known issue-no known solution), but the links will take you there.

This one shows the rear of a stock rebuilt alternator. Like Linda said, there's two posts. The one on the right marked BAT is the alternator output. This is the one where the heavy WHITE or WHITE/RED wire connects. The one on the left marked E is for EARTH or GROUND. Usually, like on my rebuilt alternator, the E will be a threaded hole to bolt your ground wire/strap to:

Here's a close-up of the BAT post. Notice how it continues into the alternator. The E or GROUND connection stops at the case.

Here's a rear shot of the GM alternator I installed that really shows the GROUND post. You can see my 10-gauge wire from alternator to frame, and the strap for engine block to frame:

And, finally, a pic where the grounds from the alternator GROUND post (10 gauge), battery negative post (4 gauge), and engine block (strap) bolt to the frame:

Hope this helps.

Post by **Linda** » Tue Jan 31, 2006 5:38 pm

Oops!
Sorry about the bad link.....
Linda
68 1600

15422444502160.jpg

15422444968391.jpg

Datsundude · Post by **Datsundude** » Tue Jan 31, 2006 5:42 pm

Thanks for the pics and clarification on where the ground straps goesÃ¢â‚¬Â¦ I guess I have to find out this weekend when I get a chance to work on my car. I will keep you guys posted.

Thanks
Vinh

Post by **ppeters914** » Tue Jan 31, 2006 6:08 pm

Just a disclaimer that that's how I did my grounds. There's a couple ways to skin this cat. Some folks run the alt ground to the engine block to the battery and then to the frame. The key thing is that all those components (and several others) need to be properly grounded to work correctly and/or not Flame Test any wiring and/or components.