I have a 1990 F-150 V8 5.0. A few weeks ago the battery light came on so i stopped into the auto parts store and they tested it on the truck off the battery terminals and it tested bad so then i went and bought a new alternator and put that on and the battery light was still on. I took the truck back down to the auto parts store and the alternator tested bad again. so i took it off and put a new one on and the same thing happened and the likely hood of having two bad brand new alternators are slim to none. I also tried replacing the solonoide (sp?) but that didn't do any thing. I asked a mechanic i know and he said that something could have blown the fuseable link. I checked that and it was blown and i replaced the link with a new one with a removable fuse. I started the truck and it blew the 30 amp fuse.

does anybody know what could be blowing the fuse or why the battery is'nt charging?

 

A fuse will blow if the wire somewhere is grounded..I would check and make sure there is no bare wires any where rubbing on metal.....If your battery is bad it would not take a charge...And the alt. will not try to charge it ...The Alt needs to see a certain voltage before it starts to charge the battery...
Have your battery tested.....if it is good make sure you have it fully charged AND check for bad wireing

 

<TABLE class=tborder cellSpacing=1 cellPadding=4 width="100%" align=center border=0><TBODY><TR title="Post 3097504" vAlign=top><TD class=alt1 align=middle width=125>chmath</TD><TD class=alt2>A fuse will blow if the wire somewhere is grounded..I would check and make sure there is no bare wires any where rubbing on metal.....If your battery is bad it would not take a charge...And the alt. will not try to charge it ...The Alt needs to see a certain voltage before it starts to charge the battery...
Have your battery tested.....if it is good make sure you have it fully charged AND check for bad wireing</TD></TR></TBODY></TABLE>

when i went to the auto parts store i had them check the battery and it tested good. I have also fully charged the battery. (thats the only way i can drive is off of the battery) and i will check the wiring.

 

What color wire was the fusible link that you replaced?

 

qoute



I checked that and it was blown and i replaced the link with a new one with a removable fuse. I started the truck and it blew the 30 amp fuse.






you should replace a fusable link with a fusable link only.

 

The COLOR of the wire will help us determine two things: the Circuit that has the problem and the Rating of the fusible link. Your Chiltons or Haynes manuals will have schematics to help find the problem. I don't have a problem with you replacing the link with a fuse, i've done it myself.

Also, a 90 may need a working Alt light for the circuit to work correctly. I'm not sure when Ford changed that, so make sure its still working.

 

ps - why do you have 2 accounts?

 

who me?


i tired to use the quote feature and it made my writing the same font and it won't let me change it. so i added a small "qoute" above it to get rid of any confusion.

 

{DOH!!!}
Forgive me...LOL
Us grampa's are easily confused!
Sorry for the mistake, I didn't see the first little quote.

 

WOW - thats an impressive post count!

 

thanks.

i only got here in 04

 

I remember the color of the wire was black....

 

ok i worked on the problem over the weekend and this is what i did. I replaced the wire link with the removable fuse with a fuseable link like the one that was blown. After i did that i went and started the truck up. The battery light went off but my dad felt the link and it was getting hotter and hotter so i turned off the truck becuause i didnt want to blow the fuseable link. We then checked all wires going from the battery to the alternator with a voltage meter. All wires were connected correctly with out any resistance.

Does anybody know what might be causing the link to be getting hot and then eventually blowing?

 

Is it possible that you are putting an Alternator made for and External Regulator on a truck setup for an Internal Regulator or visa-versa?

Here is a diagram of both.

http://www.autozone.com/images/cds/g...3d800a3a5d.gif

 

Ill check that but i dont think thats it. unless the auto parts store gave me the wrong one. I told them the truck model, year, and engine size and thats what they gave me.