alternator problem - done searches.

[woodysmom]

ok guys, i've had this problem before and i've read the forums and i've actually been a starter of a thread like this a few years back. Here's my problem.

I JUST got a new alternator today, bench tested at autozone and checked working. Producing 14v after putting on load.

I installed the alternator today and have a new optimum red top battery.

I installed the ground on the alternator, the positive, and the 2 prong connector that connects to the alternator.

After firing up the car, i tested the voltage on the battery. it was 12.35 when the car was off and 12.15 when the car was on. I disconnected the Positive cable from the battery and the car died almost immediately. At this point, i figure something has to be wrong with my alternator, BUT i just got it bench tested a few hours ago.

I disconnect the positive cable from my alternator and test to see the voltage produced by my alternator free of the battery. It produced no voltage.

My question now is what does the 2 prong connector that plugs into the alternator do? I don't have access to an FSM so if anyone could possibly look this up for me i'd appreciate it. If this 2 prong connector is malfunctioning, could if cause my alternator to produce 0 volts?

I disconnected the 2 prong connector and the alternator still produced 0 volts.

Please help me, i've checked my fuses, and checked my grounds, i can't figure out what the problem is.

Thanks!

[projectRDM]

One goes to a 5amp fuse in the underhood fusebox, the other feeds the charge indicator on the dash.

[woodysmom]

thanks! Another question, i know the voltage is internally regulated, but is there something outside the alternator that sends it a signal? perhaps something from the car is not telling the alternator to output the correct voltage?

Thanks

do you have any other suggestions?

[projectRDM]

Nope. Internal regulator does all the charging. Only if the alternator wasn't connected to the car would there be an issue like that.

[woodysmom]

hmm, I guess there may lie the problem. this another test that i've done.

I took out the 2 prong connector with a white/red and yellow wire.

To my understanding, the white/red wire should be hot (12v) when the car in on or in acc. The Yellow wire should always be hot. I took a voltmeter to confirm this and sure enough both were producing the correct voltage.

My first question is - does this test prove that the 2 wires are connected correctly within the car up to the point before the alternator??

My second question - if there is a bad connection between this 2prong connector and the alternator, would it cause the alternator to produce no voltage and how can i test whether it is in fact making a good/bad connection?

could anyone tell me what happens to their working car when they unplug this cable from the alternator - does the alt. stop producing voltage?.

thanks

[projectRDM]

The white/red shouldn't show anything unless the charge light is on IIRC. You've gotten into too much chit for me to answer right now, I'm tired and ready to drink. I'll go over it all tommorrow.

[woodysmom]

R240Na thanks for all your help and expertise. After a day of troubleshooting, soldering, and stripping, i've finally solved the problem.

The solution was a 2 step process.

I first took my alternator out and inspected it before i took it to autozone for another bench test. I had noticed that the wire that connects the copper coils in the alternator to the casing was not soldered on properly (thanks autozone cheap rebuilds). I resoldered the connection.

Then, i found out that one of the connection in the 2 prong connector was loose and sporatically giving 12v when i jiggled it. I cut the connector, attached a female connector on the cut end and plugged it in directly to the alternator.

My alternator is now functioning correctly and i'm on my way to the junkyard to find another 2prong connector.

Thank you R240NA for steering me in the right direction!

[andrave]

yeah glad that you got it fixed. those plugs can give problems. Thing is, when you change the alt a lot of people let it hang off those wires, and its bad for the plug and the harness, and it can fail.

[projectRDM]

Awesome. I figured you'd get it on your own, you were doing a pretty good job of troubleshooting. Congratulations for not being the typical 240 owner and just crying and giving up.