Hello everyone, i need help quickly. i have a 98 Expedition w/ 4.6. a couple of months ago the alternator went out. i got a rebuilt one from Advance Auto w/ lifetime warranty, along with a brand new battery. everything went fine.

well 2 days ago, on my way home the radio cut off, all the gauges died.......engine cuts off. i got a tow home. i got home and checked the battery it was 11.5 volts. i know thats not optimal but it was enough to start the motor. when i start the motor, watch the volt meter and the volts drop quickly to 8 v or so and the motor dies.

i took off the alternator, took it to Advance for testing, sure enough its a bad alternator. they gave another one w/ no problems. before i left, i had them bench test it. it tested fine. i got home installed the new alternator and cranked up the motor, guess what, STILL no charging!

well i am at a loss. i don't have experience working on cars and engines. so i am stumped. what should be my next step? i do know since the other altnernator worked for a while) theres a possibility that this alternator has gone bad too. but dang, whats the chance of that?

please help, its hot and our only family vehicle right now is my Wrangler w/ no a/c.

thanks guys!

 

You have a later model, and that's when they started putting fuses in the underhood fuse box for the alternator and the regulator. I am not exactly sure when they started this, but it's a good place to look. If you don't have fuses, I know you do have fusible links. If you were working on it with the battery connected, a wire may have touched somewhere and blew the fusible link or one of the fuses.

 

If it would help you here is a link to a diagram of your charging system.
Notice in the diagram there are three fuses that have to be good as Dave was saying above for your generator to work.
Ford calls it a Generator in the diagram an not a alternator but the auto parts stores wrongly call it an alternator.

http://i54.photobucket.com/albums/g91/subford/Electrical/Charging/1998EXCharge.gif

 

thanks for the replies. so far this morning i have:
1. swapped batteries w/ one from my jeep, no help.
2. checked the voltage accross the "fuseable links" (2) of them. and the mini fuse also. they all have the same voltage reading on both sides of the fuse (if that makes sense). so i assume since i am getting the same reading, the fuses should be ok. is this correct?
3. checked all cabling i can find: by grabbing and shaking the wiring, cheacking all terminations and looked for cuts/nicks and corrosion on any wire. everything seems ok.

anything else come to mind? if one of the fuses is bad, it shouldn't pass voltage, correct?

any suggestions? thanks for any help! this is driving me crazy. it won't run long enough to drive to a local shop and don't really want to pay for another tow.

 

Might try it again with a test light to put a load on the circuit. Meters lie a lot in these circuits.
Never use a meter if a test light will do, it will save you a lot of time and money.

Check for battery voltage on the back of the generator at the “B” terminal. If zero no charge and the fuse link is open.
The fuse link is OK check the Green wire with a red stripe at the back of your generator "I" terminal. This wire needs to be about 1 volt below battery voltage to charge, if it is zero no charge.

Also check for voltage at the "A" terminal.

You did click on the link to the diagram I posted above?

 

OK finally it "seems" to charging now. i am not sure exactly what did it. i beleive it was a either a loose connection/wire or getting a full charge on the battery. i am not sure if it was the battery or not, since it seems like it was doing the same thing w/ the other battery. i don't exactly what it was but hopefully its ok now.

thanks again!!!!!!!!!