I started out finding a 500$ 79' f150 custom 4x4 that needed alot pf work but ran and drove.
The truck didnt come with a battery but we threw one in it to load it on the trailer. Long story short ive replaced:
Starter solenoid
Regulator
All grounds and power wires (0 gauge and 4 gauge)

My question is now after testing and all these parts working fine would not having a dash cluster (idiot light model) cause the alt not to charge? I do not have a battery in it either. I have been using a jump box. The truck dies the second i pull the cables back off.

 

Yes, the idiot light for the alternator excites the alternator, causing it to make power

 

Would the be anyway to bypass this light till i can find a new cluster?

 

I "think" you can run an ignition switched hot (12v) to excite it

 

Can you elaborate? Ive only had this truck a few days and not familiar with any issues known in these ? Where to and from would i run my hot?

 

Do you need one of these?

 

I need to bypass the alt light temporarily till I can find a new dash cluster

 

Sent you an email ...

 

Isn't there a factory bypass already wired in to the harness in case the dash light burns up?

Its possible that you aren't charging with your jump box removed because your voltage regulator crapped out. If that's the case, your volt reg probably crapped out because you're trying to run your truck with out a battery hooked up.

You NEED to have a battery connected at all times while your truck is running with an alternator connected. The test of pulling the battery is an OLD test that was used on generator equipped vehicles. With out a battery connected to equalize the voltage, your alternator fan spike DANGEROUSLY high and cause very detrimental damage to your wiring harness or other electrical equipment.

So before proceeding any further, put a battery (fully charged) in there, and then check to see if you're charging. If your not, my first thoughts would be a bad alt or bad volt reg (this is assuming that I am correct about the factory bypass in case the alt lamp burns out).

 

Thank you i will try this when i get home

 

Any detail what wire to what? Really would like to get this truck cranked and start driving it to school, (my senior project) I threw a hot battery out of my daily and it ran long enough to attempt to tune the carb today (needs rebuild or replace)

 

 

So just plug the green/red to a keyed hot and i should be able to charge the battery and not burn something up? No need for the resistor ?

 

Update, everything so far is working, still using a semi new battery that is good. But the alternator isnt keeping up entirely it still dies after a few cranks

 

How long are you running between cranks? If you're starting it and then shutting it down quickly the alt doesn't even have a chance to charge.

Do you have a multimeter? If not go buy a 20 buck (digital) meter somewhere. When the engines running you should have somewhere in the neighborhood of 14.5 volts off the battery terminals (with no lights or other electronics on). If you have anything less than 14v your alternator isn't doing its job, the voltage regulator is shot, or you have a bad wire(s) somewhere.

One thing you can (should) do is clean all of your ground contact points. Block to chassis(firewall), battery to block, and battery to chassis. If you don't have a good ground, then your alt can't charge. Its honestly worth it to just replace those 40 year old cables in most situations. The braided ground strap from engine to firewall is prone to breaking and WILL cause electrical issues.

It certainly won't hurt to add extra grounds in between the bed and cab, cab and frame, and the bed and frame.

Just make sure you grind all ground points down to bare metal.

If it does turn out your alt is shot, now would be a good time to consider upgrading from the 1g alt to the 3g. Its well worth it. It eliminates the external voltage regulator and you get way more charging amps, which translates into a more efficient charge meaning less work for the alternator to keep up.