I just purchased a '85 Ford Bronco. I'm not sure exactly which engine it has, but the valve cover says 5.8 Liter V4 HO. My problem is that the alternator will not charge the battery. The previous owner installed a new alternator, battery, and voltage regulator. However, the battery gets no charge at all from the alternator. After I run the lights for a while, or start the engine a few times, the battery goes completely dead, and it will only run if I have all of the accessories turned off. All of the grounds and other wires seem good. I did find one wire, though that I'm not sure what it is. It is a yellow wire that comes out of a wiring harness near the battery. It has a large metal cylinder on the end. It's just kinda laying there, not hooked up to anything. I have no idea if it even has anything to do with my problem. Any help would be greatly appreciated.

 

Yellow wires usually go to a trailer harness.

Is there current coming out the back of the alternator?

It's got to be the alternator or harness.

Maybe take the alternator off an get it checked so YOU KNOW for sure what its disposition is.They don't charge for testing)just make sure you get to watch them do it,so you can see first hand.


Dennis https://www.ford-trucks.com/user_gallery/sizeimage.php?&photoid=1733&.jpg



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[updated:LAST EDITED ON 04-Mar-02 AT 10:34 PM (EST)]Like Dennis says, get the components checked out - most auto electrical shops can test the regulator and alternator.

One other thing - if you have now run the battery down (discharged), you must recharge it with an external battery charger. If you try to recharge a dead battery with the alternator, you run the risk of overheating the system, blowing the regulator or alternator - or- both. The alternator has to run FULL BORE to try and charge a dead battery, and supply enough 'amps' to run the accessories, as well. Running at full output means HEAT, and heat ruins electrical stuff!

Have your components checked out - recharge the battery - check and recheck your wiring - it's got to be hooked up correctly to work properly - get a cheapo repair manual from the auto parts store to help you through the process, $'s well spent! Good luck.

 

You may also check the grounding of the regulator. Remove it from the inner fender and scrape the paint away from around the two bolt holes there (on the inner fender) and re-attach it. Are you sure the previous owner installed it correctly (by being sure it was properly grounded before applying current)? Is it possible that he/she installed one improperly and fried it before giving it half a chance? My '85 recently took to overcharging (halfway between neutral and "C" on the ammeter). The lights were bright as day, and the needle moved even higher with revving the engine. (The battery was not taking a charge, as I discovered). No problem, voltage not being regulated, must be the regulator, right? Changed it out properly, fixed problem. For two days! Next, no charge at all (just like yours). I bought a new alternator and, just for kicks, picked up another regulator. I changed out the alternator, fired her up, and..... no charge, just as before. Changed out my two-day old regulator with the one I picked up, and no problem since. My reasoning..... the alternator was the problem to start with (and it was shot..... I could give it a good spin and it would go for half a minute.... no brush contact at all), and it took the regulator out. I changed out the regulator, and the bad alternator killed this one in two days. Changed the problem alternator, put in another regulator, and fixed the trouble. Moral of the story, just because the previous owner installed a new part doesn't mean it isn't already dead as a result of another problem, or because of improper installation. I'd check the regulator, also.

 

Inspect the wiring harness coming out of the side of the alternator up to the starter solenoid mounted on the passenger fender just behind the battery. If the fusible link was previously replaced and wasn't wired in permanently with wire terminals, you may have a bad connection there caused by corrosion or brittle wires caused by heat. Look for any electrical tape and start unwrapping it and inspecting the wires. I've experienced this same problem with my 89 Bronco. This was the cause of mine. Someone had just taken the wires and twisted them back together and put electrical tape around them causing problems later down the road.

Bronco894x4