Need serious wiring help

[76_bronco]

I have a 3g alternator in my 76'. HAve had nothing but issues since day 1 with it and continue to have wiring issues. Now just to verify what i have right now.

They yellow wire currently comes out of the alternator and goes to the stud on the back along with my power wire from the battery.

The black and white comes out and goes right back in

The green and red runs to the wires from my original alternator harness that has a green,yellow, and a thick black wire with a fusible link in it.

Now that green and red I have run to the green wire from that original harness, that thick black goes onto my selonoid, and currently have that original yellow hooked to nothing. I tested the yellow and its Hot with the key off

When I turn the key i get nothing at all, but If I jump it the truck fires up and runs. What do you guys think, im lost seeing how Im not good with wiring

 

[DirtDonk]

First, alternator hookups usually have nothing to do with it not starting.

When you say "jump", do you mean from another battery? Or just jumping the wires on the starter relay/solenoid?
If that, since it works when you jump it, sounds like the battery is good. And it sounds like the starter is good. So that leaves just the Red w/blue wire or the relay itself.

Are you jumping from the battery to the small terminal where the Red w/blue wire is? Or are you jumping across both large terminals, direct to the starter?

Paul

 

[76_bronco]

jumping from Both large terminals

 

[Viperwolf1]

http://www.bcbroncos.com/3G 3 wire with water mark.pdf

The green-red wire on the 3G goes to the green-red wire from the old regulator. Follow the diagram.

 

[DirtDonk]

Ok, try this then. Verify the position of the wires. The Red w/blue wire with it's 90° boot should be the one next to the battery side. Brown wire on the "I" terminal should be on starter side.
If correct, pull the Red w/blue wire off it's terminal and jump from the battery to the small "S" terminal. If the relay clicks and the starter spins, your relay is good and you'll have to trace the wire from there back to the ignition switch to see where the problem is with that circuit.
If it doesn't work when jumpered that way, either the relay is bad, or it's not sufficiently grounded to the fender.

First pull it off and clean the mounting points good. Re-attach it and see if that helped. If not, replace the relay/solenoid.

Paul

 

[76_bronco]

Now that diagram tells me to run my 4ga wire to the starter selonoid were every other diagram has told me to come from the positive side of the battery

 

[Viperwolf1]

Now that diagram tells me to run my 4ga wire to the starter selonoid were every other diagram has told me to come from the positive side of the battery

Same thing if there's a big cable connecting them.

 

[76_bronco]

ok Paul i jumped from battery to the red/blue wire plug and it cranked over

So that means there is an issue with my ignition circuit somewhere??

 

[76_bronco]

Does it sound like I have that alternator hooked up correctly by how I described?

 

[Viperwolf1]

Did you remove any wires from the solenoid? If not the fuseable link may be bad there.

 

[76_bronco]

I have from the original harness the green/red is hooked to the green/red from the alternator, The thick black wire that has the factory fusable link to the S side of the starter selenoid, and that yellow wire that is constantly hot hooked to nothing.

What should I do with that yellow wire

 

[DirtDonk]

You can cut it or cap it off. I prefer to cap it, since it can possibly be used for something later on.

Does everything else in the truck work currently? Things like lights, heater, radio, cigar lighter? If so, then the Black w/red wire with the fusible link is still good. Are you saying that you have both large black wires now attached to the starter relay? The original one, AND the original one from the back of the alternator?

If everything else works, then yes, you have an issue with the Red w/blue wire. Either the wire itself, or the ignition switch is causing your issue.
Just to make sure though, how tight was it on it's terminal? If loose, that could do it too.
Do you have a volt-meter? If so, with that wire disconnected from the relay, have someone turn the key to start and hold it there. You should see full battery voltage and be able to wiggle the wire and the key without it shutting off the power.

Do that test and let us know what you find.

Paul

 

[76_bronco]

right now on my starter relay/selenoid I have on the S side the battery cable to positive side and that original black wire with the factory fusiblelink......On the other side is just wire running to the starter and then just the blue/red and brown wires on top of the selenoid..

When I do the test with the meter should I be checking that blue/red wire itself or were it plugs onto the selenoid?

And yes both lights and heater are working

 

[Steve83]

Test the R/LB wire's voltage, preferrably while it's still attached to the S terminal on the starter relay. When the R/LB wire is disconnected, the S terminal on the relay will be grounded through the relay's coil & mounting tab.



Was the truck originally a stickshift, or an auto? What does it have now?

 

[DirtDonk]

Good call Steve! I totally forgot about the possibility of there being a neutral safety switch.
One more thing to zero in on 76, but it's a more likely scenario than a bad wire.
Even on a Bronco...

Paul

 

[76_bronco]

The truck was originally a 3spd on column but was switched to auto and worked fine prior to my rebuild. I had it starting with the key before I installed this alternator and I have it hooked up the way everyone has showed and explained but now I have no start from the key. Also I have the column loosend up to replace bearings in it but have put the shifter as far into park as possible and still have nothing, does the column wiring have anything to do with the ignition or did the ignition switch just crap out all of a sudden?

 

[DirtDonk]

Worth a check. Do you have working backup lights? If so, there is a switch somewhere. If stock, that switch is also the neutral safety switch.

First of all, since you messed with the alternator, and therefore the positive battery cable at some point near the relay, check it for cleanliness and tightness. Loosen and twist it back and forth a bit on the battery, just in case. Check to make sure you're getting good contact at the relay/solenoid-thingy.
You probably have done all that already, in all this back and forth checking, but just make sure.

Take a look for a switch housing attached to the shift shaft going into the driver's side of the trans. If it's there, follow the bundle of four wires up into the engine compartment. Would normally be a four-wire plug up between the engine and firewall, with 2 Black w/red wires (backup lamp) and 2 Red w/blue wires (NSS interlock to starter relay).
Check the connector, make sure it's tight. If so, pull it apart anyway and connect the two Red w/blue wires together with a small jumper wire between them.
Try to start again.

This all "assumes" that the person that did the swap actually did the proper thing and installed and adjusted a working NSS.

Good luck.

Paul

 

[DirtDonk]

Hah! gotcha.
Didn't think anyone was watching yet, did you?

Paul

 

[76_bronco]

Looks like I have alot of testing and checking to do when i get off work. Wiring sure hasnt been my friend..

Thanks guys really appreciate it Ill check all this stuff and get back to you with what i come up with

 

[76_bronco]

When i run the volt meter on that blue/red wire at the selenoid, if I get no voltage would it be the ignition switch or would that wire be bad. Im just trying to get answers so when I do the test I dont have to hop back on the computer for an answer