having an issue | Ford Explorer Forums - Serious Explorations

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having an issue

November 3, 2008
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alright so im kinda stuck as of right now.

i just replaced the alternator in my explorer. the engine starts fine but if i do the battery test where you pull one of the leads off, the explorer shuts off completely where it should stay running if the alternator was powering the engine.

i really dont know where to being on why the alternator is not keeping the engine running.

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well this will sound dumb but dont pull the battery lead off

lol yes but if you pull the battery lead off then the engine will keep running because the alternator will power the engine.

by pulling off the lead it will show if the engine is running off the battery instead of the alternator. which means that the alternator or wiring is not working right. the alternator has been tested by advanced auto and is working.

You need the battery hooked up for the vehicle to run, disconnecting the terminal while the car is running is bad for the computer. Don't do it. I hope you didn't just replace your alternator because of this "test".

you do not need the battery for your vehicle to run lol you only need your battery to start the car. after that your alternator takes over

either way you are all getting around the point here.... the alternator is good but its not recharging the battery or keeping the engine running. i even did a voltage test one the connections to the battery. while the car is off and while its running. and the voltage drops and if i turn any accessories on than the voltages drops more

Ok your car WILL NOT RUN WITH OUT A BATTERY!!!!!! It is a alternator not a magneto. A magneto is the only device that can keep an engine running without a battery.

alright then how do you explain that i can pull the battery completely out of my honda and set it on the ground and the car still be running as normal?

im not trying to be an #######... its basic electronics.... the alternator is just a generator... a generator that keeps the engine and accessories with enough power to run and it also recharges that battery.

and im just gonna go ahead and add this page i found that explains what and alternator does and it even has a cute animated picture that shows how things work when engine is on or off... just incase someone else feels the need to argue that


i guess ill just hafta answer my own question

i have basically 2 options that i can think of

1. i can get out my digital meter and run a continuity test on wires coming off the alternator to wherever they might end and work my way from there to find some type of faulty wiring

2. take the explorer to a garage and have it hooked up to a computer for a diagnostics test to help narrow down the possibilities. the plug is under the steering wheel next to the hood release if anyone was wondering.

if anyone has any other ideas let me know

You could very well be correct. Most vehicles will run on just the alternator. But that is a very, very bad testing procedure. I can't tell you how bad that is. I would never attempt such a thing, so I can't tell you if it will work that way or not with this vehicle.

ok well here is an update

as of now alternator is good, wiring is good, and all fuses and relays are good

first i got a wiring diagram and then i did continuity testing on all the wiring related to the charging system and everything came up good but there is one wire im not sure where it ends... it comes off the batter and then goes down


any idea where exactly that wire goes to so i dont hafta go digging for it?

and if i leave the volt meter on the battery and start the explorer... the volts drop below 12v and then if i turn on other accessories then it drops more... which definatly means that the alternator isnt doing its job somehow