Charging system not charging - ideas?

[Robb]

I grabbed an alternator from a fellow 240-er last week to throw in my S14 since I was already having charging issues with the alternator previously in the car. After snapping the radiator neck somehow (Happy birthday, right? http://www.patuned.com/forum/images/smilies/FUU.gif ), I got the alternator in put everything back together, only to find out that the alternator isn't charging.

Now, what confuses me:

- Previous alt was a 90A, charged at 13-14v with dips below 12. The battery and break light would come on, indicating the charging problem was present.
- This alt is an 80A, it sat at about 11.5v with no battery or break light on.

Ideas?

[nismoman]

Check your main grounds. Are you sure the new alt is good? Should def have over 13 volts with the car running.

[Robb]

I assume that it is good, the dude I bought it from states it worked fine for him. I'm going to get it tested today just to eliminate the possibility though. Grounds are good to go.

[Silviaracer1988]

your supposed to get an alternator that is the same amp or higher. you can't go lower or it wont charge anything and if it does it'll be weak as hell. learned that in auto class

[Robb]

The extra 10A is for the fog lamps, IIRC. Not using the fog lamps shouldn't cause an issue.

[Silviaracer1988]

not to sound like a dick but did you check all your connections?

[Robb]

Hey - I work in IT, it's the first question I ask, not a big deal at all! Legit!

I did. The only one that concerns me (from research today) is the two prong connector. I will double check that.

[Silviaracer1988]

other then that, it could be like my buddy's car. he fried his positive wire somehow and he didn't know. we put a brand new alternator in and it wasnt charging. and the only reason why put it in the first place was because the battery light came on. the alternator was still good. so check for that too.

[Likethunda]

Check the Grounds... Worked for me..

[Likethunda]

you can also get a Multimeter and check for any resistance on the negative side of the battery..... if you do, then u got some ground issues...

[DERRICKMC]

check your bulb in the instrument cluster if it doesnt light up when you turn to ignition the bulb is burned out. and the alternator does not get excited unless the bulb works and completes the circuit the wire is white with a red strip.