I have a 1998 Ford Expedition the battery was dead so I replaced it then the altenater was bad. The battery gauge in instrument panel isn't reading and the battery seems to loosing charge had new altenater tested at auto zone it's good what can be causing this to happen..

50

Asked by Nov 16, 2014 at 10:24 PM

Question type: Maintenance & Repair

1998 Ford Expedition  dead battery   "New altenater & new battery". Had tested
everything tests good. Need to figure out cause of battery draining when sits over a few
hours.

11 Answers

78,195

Disconnect 1 battery cable, put a test light between the battery post and cable end, if the light turns on then you have a draw that will kill a battery, first disconnect the alternator's electrical connections, if the light turns off or drops to a dim glow your alternator is bad, if the light stays lit then you will have to start removing the fuses one at a time noting where it was until the light goes out or just a dim glow, when that happens then you have to find what is on that circuit and repair it, then reinstall the fuses making sure the light stays off. HTH

50

Will check into that... Thanks for the advice. Will update findings if any. TY!

240

If your Expedition goes completely dead, to the point in which you lose the memory of radio presets, you likely have a dead short. I would change your battery cables, replace the negative on first. I have had this occur to my own Ford vehicle and have found this to be the problem a time or two on some of my friend's Ford vehicles. Good Luck.

50

Turns out the refurbished alternators I was getting were defective. I bought a "new" alternator and it ran fine, gauge read the appropriate voltage everything was good. Then out of the blue the voltage gauge dropped back down and the alternator stopped charging. It's not draining my battery anymore so it's not parasitic drain. If I let it cool down it will go back to normal until it heats up. Any ideas?

78,195

Still sounds like alternator trouble, make sure all of the wiring and connectors are good. It is going to be a little tough to find as now you have to wait for it to go into failure before you can perform diagnosis.

50

The truck just did it again. The battery's almost completely dead, for some strange reason the alternators not charging the battery. What exactly does the alternator need to generate current?

3 out of 3 people think this is helpful.
78,195

Just an activation signal from it's regulator but the wiring has to be good for the regulator to sense the voltage so it won't full field the alternator and burn it out.

50

What does the green wire with the maroon stipe coming from the alternator do? I read that it controls when the alternator engages and if i jump it that the alternator will turn on. Sure enough when i jumped it everything started working fine.

1 out of 1 people think this is helpful.
78,195

It should be a violet wire, but who knows. I am thinking that your rig has a computer controlled alternator, and that is the actuator wire from the ECM, you may have to have the ECM tested for proper output signals, but I still would not rule out a wiring problem.

50

Yea i believe the ecm controls it, i unbolted the plug that goes to the ecm and reseated it and so far everythings good. I hope that fixed it but seems too simple to be it.

1 out of 1 people think this is helpful.
78,195

Sometimes it is the simple stuff that eludes us.

1 out of 1 people think this is helpful.

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