One day in the summer the battery light came on and the voltmeter dropped to a low level. Eventually the battery went dead. So my dad replaced the alternator. Didn't fix the problem. So we took it to the mechanic and they found that the fusible link from the solenoid to the alternator was shot. So they took it out and put in 2 inline fuses of 30 amps each. It fixed the problem until I went plowing last weekend. After about 10 minutes of lifting the plow up and down the battery light came on and the voltmeter dropped again. So I checked the fuses and they were both blown. I don't know why it is doing this. ANy ideas? Thanks guys.

-Matt

P.S. The truck is a 1987 Ford F250 with a 5.0 L V8.

 

The 30 amp fuses are too small. Replace them with the correct fusible link and see what happens. I think the smallest alternator they put in these trucks is around 60 amps output.

 

I was thinking that about the fuses but wanted to double check. I took them out and put in a new fusible link and it seems to be fine. I will know for sure next time I go out plowing! There are 3 wires that all come from the alternator to the fusible link. All three hook into one fusible link then go to the solenoid....is this right? Or do they all need seperate fusible links? Thanks...

-Matt

 

They look like they all go to the alternator, but you should have one I think, red/black, that goes to the alternator, a yellow that goes to the fuse box, and I forget where the other one goes. This is the main spot where the whole truck's electrical system is fed.

 

Should all three of these wires hook into the one fusible link or should they all have their own fusible link? Thanks.......

-Matt

 

There should be a Pink one wrapped up with tape in the harness going to the firewall from the starter relay.

 

Talking about fusible links, I just replaced the pos and neg battery cables on my 85 F250/460 and found that on the terminal that the batt pos connects to on the solenoid, there were several connected and one had a wire burned away from the connector.
It looked like a fusible link, but it was burned right at the wire end connector.
Is there a wiring diagram here I can view that will tell me what was connected to that terminal?
This was a non-runner that I got, and the charging system is not charging.
I was thinking that it was the Alternator power wire perhaps?

I just got a red FEB registration paper from DMV so it will be up and running soon!

 

Just tell us what colour the wire is.

 

The cheap Haynes manuals that are usually terrible, have pretty good wiring diagrams in the back for your year.

 

It's a red wire and appears to be toast from the fusable part to the starter relay connection.

 

Whatever the wire was, I swapped in a fuse connection and when I hooked up the battery, damn, I never knew a 20 amp fuse blowing could make so much noise!
It also made a sizzle sound by the drivers side fender.
I looked around and found some idiot used a razor blade to strip some of the insulation off the wires (as if to test them?) all over the plastic fender and never repaired them!
Once again "IDIOT" (AKA PRIOR OWNER)
:-staun

I started testing for continuity from the fuse connection to them.
It fed to all of them.
I then tested resistance to ground, and it was just as good!

Then I saw it, a big fat red wire going into the dash right under the master cylinder had welded it self to the spiraled wire around the brake line!
Cut out the bad part, soldered it back together, heat shrinked it, electrical taped it, and the charging system works now at 14.18 volts!

 

Was just wondering, The problem i'm having or think i'm having is the wires from alt to relay to me get too hot.Melted them once so fixed them.They still seem to me too the touch to be getting to warm.There is a bit of a mess here that i tried to clean up from prev owner.Any info would be helpful.
Thanks

 

I could be totally wrong on this but what does your voltmeter say? Is it reading into the red area on the right? If so, you could be overcharging your battery. Causing the wire to get hot. This is just a guess. And if it is being overcharged then your voltage regulator is probably shot. Get a voltmeterand hook it directly to your battery. With the vehicle off you should be around 11.5-12 volts. With the vehicle running you should be between 12.5-14.5 volts. Check that and go from there. Good luck.

-Matt

 

"There is a bit of a mess here that i tried to clean up from prev owner."

What size wire are you using for the repair. The one from the "bat" lug on the alt to the starter relay should be at least 10 guage, 8 or 6 guage would not be overkill.

 

The actual voltage range for a 12 volt system is 13.8 to 14.2 and with the engine of it should be at the least 12 volts.
To put 12 volts into a 12 volt battery, you need a 13.8 volt pressure to push it in and to supply the needed juice for the rest of the electrical system.