Here's a fun one...

[Alfred Lord Tenniscourt]

I just lost all power. I went to crank up the truck, it turned over nice and fast like normal, then cut out. Now, there is no power to anything at all. I cleaned and tightened the battery cables and the starter relay connections. Still nothing. No headlights, no starter, no interior light, no electric fuel pump... Nothing.
Do batteries ever just quit like that?

[67fordman1]

I have never known of a battery to die that quickly. Sounds like a loss of ground.

[BobbyFord]

Check the fusible link at the solenoid.
Electric fuel pump...?

[Alfred Lord Tenniscourt]

Yeah, she's got a megasquirt 300' six in her...
I will go over the connections again this morning. The weirdest thing is that I have a continuous piece of stranded copper battery cable to the starter relay, then I have four separate circuits that come from there and none of them are working.
Hey wait, now that I think about it, I wired an 80 amp marine fuse in that protects everything in the cab. If that blew, it would shut everything down because it would shut the controls for everything down. For instance, it wouldn't shut down the primary power source for the headlights, but it would shut down the 12v signal that controls the relay.
I really hope this is as simple as re-setting a breaker...

[Racer Z]

It's going to take a lot to blow that 80 amp fuse, like a direct short.
Do you have a volt meter or a test light? Check the voltage at the battery and then at several key locations.

[fordman]

bad starter relay maybe.

[basketcase0302]

The weirdest thing is that I have a solid copper battery cable to the starter relay, then I have four separate circuits that come from there and none of them are working.

You do mean a "stranded copper wire" I hope. The same size of a stranded wire carries a lot more amperage than solid wire of the same gauge. Never seen solid wire used on any part of a vehicles wiring from the factory, (even grounds where there's never much load).
I'd bet the issue is with the 80 amp fuse you have / or the battery itself.

[Whateverman]

Check the fusible link at the solenoid.
Electric fuel pump...?

i've never seen a fusible link in one of these trucks yet,inline fuses- yes,fusible links -no

popping an 80amp breaker? ho-ly man, have you checked to see if the insulation on your wiring is intact or not? i had a sorta kinda similar problem a while back on my ol' diesel f250,no popping breakers,but a whole lotta sparking and burning old road grime off the frame where the way too long (3ft too long...previous owner....) starter cable (heavy ga. welding cable) had rubbed through its insulation and grounded out on the tie rods....that killed the battery P.D.Q. as well

[basketcase0302]

Whateverman on Thu Feb 03, 2011 11:10 pm

BobbyFord wrote:Check the fusible link at the solenoid.
Electric fuel pump...?


i've never seen a fusible link in one of these trucks yet,inline fuses- yes,fusible links -no

As far as I know, all our trucks had a fusible link from the factory! A lot of folks have "butchered" them-instead of replacing them as they should. Yet an 80 amp circuit breaker in the wiring from the factory would not be stock though. That's the same hack work described above instead of correctly replacing the fusible link, (which can be done).
Lord Alfred, I don't believe I saw what year truck this is?
Here's an example of the fusible link wiring, but might not be correct for your year:

[BobbyFord]

i've never seen a fusible link in one of these trucks yet,inline fuses- yes,fusible links -no

In this diagram, check the black wire from the alt. to the solenoid: http://www.fordification.com/tech/wirin ... _quick.jpg

[Alfred Lord Tenniscourt]

Basketcase, do you think there might be just an ohm or two of resistance in that fusible link? I have never understood just how the ammeter would work if there is practically no resistance between the battery and the alternator. If there was just a touch of resistance there, it would force just a little current around the ammeter.
I know a lot of people can't get their ammeters working right, it might be because the fusible link has been replaced...

Whateverman, I had the same problem with my starter cable. It didn't actually short, but someone had a huge piece of heavy cable spliced in there and it was a matter of time before something happened to it, so I changed it... I also had a piece of solid 14-2 romex between the battery and alternator when I got the truck. After that, nothing surprises me too much...

[Racer Z]

Nice wiring job Alfred Lord Tenniscourt.

Just to clear up what seems like confusion, there is suppose to be a fuseable link at the alternator. Without it, you would have a big amperage unprotected wire. Standard fuses and circuit breakers can't handle the full load of the alternator when everything is powered up. That would be one massive direct short if something happened and there was no protection. Can you say, "Fire in the hole!"?

It's my understanding that you can make your own fuesable link, rather easily. You need a six inch section of wire, two sizes smaller than than the wire it's protecting. Make sure the insulation is teflon or something that won't burn when it overheats. Add this short & small wire at the beginning of the wire nearest the power source. In the case of the alternator, the fuseable link connects to the alternator and then to the 8 gauge wire that runs out to feed the battery, amp meter and rest of the truck.

If the circuit overloads, the fuseable link melts in half before anything else can. It works like a fuse, but can handle heavier current.

And No, this fusable link won't show up as resistence in an Ohms Meter test.

[Whateverman]

well,now I've learned something new - there...no more learning for today

[cdeal28078]

Not saying the wiring is perfect in these old Fords but my 71 is still working great. As far as the wiring to the head lights there is a perfectly easy fix for that. It is called Whiter Brights or something like that. It is on the site under Tech. articles. I did it on my 71 using two relays that put power straight to the head lights and take all of the amp load off the head light switch and dimmer switch.
clint

[basketcase0302]

Glad you got it going. First description sounded like some crazy wiring. I like what you've described you've done to the truck. I'll always make an attempt to repair the original wiring in my truck, (I've yanked out quite a mess of wiring since I've owned mine).
I also realize some of our trucks have just been too butchered to do so. Agreed...the headlight upgrade is the best one anybody can do to our trucks.