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Sat Jun 21, 2008 12:10 am

i am having a little problem with my alternator on my 81 caddy diesel. i just put a new alternator on it and i dont seem to be getting any charging going to my batt. The old alternator didnt have a ground on it but the new one has a plug were i guess u can ground the alternator to the block. and how do you check to see how much the alternator is putting out.

Sat Jun 21, 2008 12:40 am

What plug are you talking about? There should be like a ground strap leading to a bolt on the alternator housing somewhere, not a plug, for the ground. A good ground is important, as that type engine has the alternator and adjusting brackets insulated with rubber bushings. If need be you can run a ground wire from one of those 8mm assembly studs on the edge of the alternator directly to the battery negative.

Also important is having a functional warning light on the dashboard. Alternators will seldom start charging unless you "prime" it by having current flowing through to that warning light.

Hope that helps
Andy

Sat Jun 21, 2008 2:11 am

well on the new one i got it has no bolt, its all plugs. there is the spot for the plug in for the harness and two other male end wire conneters one with a + next to it and one with nothing by it so i guess that one is the - side

Sat Jun 21, 2008 4:52 am

What model type of alternator is is? I cannot recall ever seeing a system ground in simple push-on wire. The positives go through those large wires, the ground is also going to need a solid connection. I was talking about the long bolts that hold the alternator together and not a decidated electrical stud. They are longer than the whole housing and have threads that stick out. Like the one shown below the arrow on this picture:

Sometimes you'll see an extra "W" connection, that's for a tachometer connection on certain diesel models.

Motorola type alternators had the ground connection as shown here:

Sat Jun 21, 2008 9:08 am

here is the picture of the alternator i bought. http://www.autozone.com/R,APP180710/vehicleId,1253...Detail.htm

Sat Jun 21, 2008 3:20 pm

Looks like the Bosch one I posted the picture of above with the radio noise suppressor hooked up.

Okay, using their picture, I added some arrows. Connect a ground strap/wire/cable to one of these locations. If there is no stud emerging from those locations to put a nut on, you might have to get a machine screw to thread into that hole.

Sat Jun 21, 2008 4:43 pm

ok cool but i was looking at my alternator and it is mounted solid with no rubber bushings so i thing it will ground it self out and i was looking more at the plugin for the alternator and with further inspection i saw that the wire that goes to the light in the dash has a cut in it right at the rubber plug so i bent it over a little and i found the wire to be broke all the way through. so i repaired it put it all together and now im getting the 14 volts i need so i think i may have fixed it.

Sat Jun 21, 2008 5:00 pm

No rubber bushings? You must have a later engine or setup in there or something. I much prefer the solid mountings they used later on!

Ah good, a bad wire to the warning light, I mentioned that in my first post above. It is very important! Glad you found it and fixed it. If this happened when you still had the old alternator in there, chances are it was still good too.

-Andy