I recently purchased a 87 f150 with a 4.9l L6, my voltage meter on the dash was low so i bought a new alternator and battery. My battery light is still on and my alternator is not charging the battery, i had the alternator and the battery have been tested and are good what else can it be...

 

Loose belt or faulty tensioner, but more likely, bad wiring, or bad alternator. I would get the system tested at Sears(usually a freebie) or anywhere they will check the charging/battery system for free.

Discount Auto shops are trying to operate in a very competitive market, the prices and quality are very low, and if you bought the alternator at a "discount parts store" I don't give that alternator more than a year till breakdown( especially if it is a "lifetime warranty" deal). Remanufactured or rebuilt alts can be bad right out of the box. It hasn't happened to me, but have read enuf stories on this website about those types of problems.

I was suckered by Pep Boys 7 or 8 times, I had the lifetime warranty alternator, and it would die every 6 to 12 months. Then the next would die, then the next , and so on.

I would get a Haynes manual, it will help you with basic trouble shooting of the electrical system.


Try the electrical, wiring forum under the miscellaneous section and in this website for further info.

 

Thanks for the help I am going to check for shorted or frayed wires and hopefully it is that. I allready had the alternator and the battery tested and they were good. I am figured it was a bad ground wire or frayed wire but i just wanted another opinion.. Anyway i just want to say this is an awesome website, i use the same type thing for my saltwater fish. Thanks again

 

every time I put a new alt. on a Ford I also replace the large wiring harness connector/plug on the alternator as they are famous for going bad.

 

I replaced that too.

 

Is there a main ground or main fuse if there is , where would it be?

 

didn't Ford trucks have 2 different alternators in 87? One was an internal regulator and one was external. USMC, does your alternator have 2 plugs going into it, or does it have 3 wires bolted on the back?

 

It has 2 plugs on it, it is internal regulator. i just broke down and brought it to an auto shop for a electric test on everything so i can find out exactly what is is.

 

It was a fuseable link it cost 38$ for the rewiring and the part and the diagnostic test and i am glad it is over me and my truck were about to

 

Great news. Did they give you any idea why the fuse link popped?? Or was it just becoming corroded?

 

It was old and worn out.