Wiring: 3G, MSD, and Painless 20 circuit fuse box

[JSmall]

Please excuse my horrible attempt at a wiring diagram. I’ll try to clean it up when I have a good idea of what is going on. My main concern is the wiring from the Fuse box to ignition. Currently I have the Black/yellow wire coming from the B+ side of the solenoid and it runs to the gauge cluster which is capped off because I’ll be running a voltmeter. There is a smaller yellow wire running to the ignition from the Black/yellow wire. If I change it to the setup in the diagram does anybody see any issue that would come up? I know I’ll need to run everything coming off the black/yellow back to the fuse box. I also need to figure out why the red/blue is capped off right out of the ignition.

I have to redo what I’ve already done because my stock fuse block was bad and I didn’t find that out until I was finished. I want to do this one more time and I want it to be perfect. With the Painless fuse box I should have plenty of circuits to do this correctly. Even if it means starting from scratch.

Any help would be greatly appreciated. I will update the drawing with any suggestions and use the final when I’m installing the fuse box this weekend.

Thanks

 

[JSmall]

Does this make more sense? Having the black/yellow come off the b+ side of the solenoid with a fuse?

 

[eric0o1]

I would actually move the yellow/black wire that sends power to the ignition switch off the solenoid and go to the alternator side of the 175 amp fuse you have on your schematic. That is how I design every harness I do here anyhow. That would provide you the extra protection while avoiding having to install another fuse, and it will also remove one of the wires you have at the starter solenoid.

Also if the red/blue wire at the ignition switch is capped off, how are you getting starter signal to the solenoid? Also is the red/green wire you are showing at the ignition switch tied the the black/green or are you using a universal switch?

 

[JSmall]

Like this? If I hook it up like this, is it still a constant 12v to the ignition?

I have two red/blue wires coming off the ignition and one of them is hooked up. It's the one that goes from the solenoid, through the firewall, under the dash and out the passenger side of the firewall. It comes back through the firewall and connects to the ignition. I'll have to check that out.

The red/green wire connects directly to the 3G alternator. It could splice into the black/green going to the old fuse panel right now. I'll have to check that out. My Bronco is stored at a friends house so I don get up there all the time.

Thanks for all the help

 

[eric0o1]

That’s exactly how I would do it.

The red/green wire to the alternator just needs to be a switched ignition 12v source, it doesn't really require any amperage so you can essentially share any circuit for this. I sometimes use whatever I'm powering the choke with to also provide the exciter wire to the alt. This would keep you from having a lot of unnecessary wire at the switch and to keep you from having to pass extra wires through the firewall.

I'm not picking apart they way you are trying to do it, just offering ways to keep it clean and to maybe make it easier.

 

[JSmall]

That’s exactly how I would do it.

The red/green wire to the alternator just needs to be a switched ignition 12v source, it doesn't really require any amperage so you can essentially share any circuit for this. I sometimes use whatever I'm powering the choke with to also provide the exciter wire to the alt. This would keep you from having a lot of unnecessary wire at the switch and to keep you from having to pass extra wires through the firewall.

I'm not picking apart they way you are trying to do it, just offering ways to keep it clean and to maybe make it easier.

I really appreciate the help. I'm hoping to have this picked apart so I do it right the first time.

 

[JSmall]

I'll be using the last diagram and starting tomorrow unless someone has a better suggestion. I'll let you know how it goes.

 

[Moon's74]

black/yellow

I recommend putting the black/yellow wire on the solenoid side of the 175A fuse. This gives the ignition some protection in the event the alt/regulator fails and surges through the fuse.

 

[Viperwolf1]

I recommend putting the black/yellow wire on the solenoid side of the 175A fuse. This gives the ignition some protection in the event the alt/regulator fails and surges through the fuse.

...but does absolutely nothing to protect the black-yellow wire from a short to ground. Not that the 175 amp fuse would do much either. I prefer to use a fusible link in that wire.

 

[Moon's74]

...but does absolutely nothing to protect the black-yellow wire from a short to ground. Not that the 175 amp fuse would do much either. I prefer to use a fusible link in that wire.

x2, didn't think of that one. I also used other protection...a 60A circuit breaker.

Just don't want to hear of any fire balls in the future.

 

[JSmall]

...but does absolutely nothing to protect the black-yellow wire from a short to ground. Not that the 175 amp fuse would do much either. I prefer to use a fusible link in that wire.

More like the 2nd diagram I posted?

 

[Viperwolf1]

More like the 2nd diagram I posted?

Yes, more like that.

 

[JSmall]

Yes, more like that.

Thank you!

 

[DirtDonk]

I was just wondering JS. Is this a stock wiring harness with a Painless fuse box? Or is it a full Painless harness?

I see you list 10 gauge wire feeding to the switch (Black w/yellow), and feeding the switched side of the fuse box (Black w/green). Depending on how exacty this is wired, it looks like you're running every "key-on" accessory from that one wire.
If this is the case, you might want to consider the standard switch has two types of "on-with-the-key" circuits. One is the ACC center post (Black w/green), which is on in both ACC and RUN positions. While the other is on only in RUN and handles things like the ignition and alternator.
Make sure your ignition system is on only in RUN, or you're going to be running the risk of overheating it while you're just sitting there listening to the radio.

Just making sure...

Paul

 

[JSmall]

I was just wondering JS. Is this a stock wiring harness with a Painless fuse box? Or is it a full Painless harness?

I see you list 10 gauge wire feeding to the switch (Black w/yellow), and feeding the switched side of the fuse box (Black w/green). Depending on how exacty this is wired, it looks like you're running every "key-on" accessory from that one wire.
If this is the case, you might want to consider the standard switch has two types of "on-with-the-key" circuits. One is the ACC center post (Black w/green), which is on in both ACC and RUN positions. While the other is on only in RUN and handles things like the ignition and alternator.
Make sure your ignition system is on only in RUN, or you're going to be running the risk of overheating it while you're just sitting there listening to the radio.

Just making sure...

Paul

I absolutely hate that this is so confusing for me. If I wire it like this, will I have the problem you’re talking about? This is a painless fuse panel only.

From my ignition I have the following:
Black/yellow – Constant 12v. Solenoid to ignition with 60 amp fuse
Black/Green – 12v to panel in run and ACC
Green/Red – 12v in Run. Ignition to Alternator. I was going to combine this with my choke and run it to the switched side of the panel. Is this what you’re talking about? Better to leave it the way it is?
Red/Blue – 12v in Start. Capped off because it went to the old ignition. I’m running MSD now
Red/Blue – 12v in Start. Ignition to Solenoid
Red/Green – 12v in Run. Not sure about this one yet.

Thanks again for the help. It is really appreciated

 

[eric0o1]

the fuse block does not provisions for ACC only ciruits. It is an internally bussed fuse block so each side can only have one type of power source. There is no where to connect the wire from the ACC position of the ignition switch.

In most cases this for the radio anyhow. To keep the ACC function, you could run a wire from the ACC position of the switch to an inline fuse, and then from the fuse to the radio.

 

[JSmall]

So I'm still in the clear the way I have it wired?

 

[eric0o1]

the green/red and the red/green will only be fused by the 60 amp inline fuse you are running. Just a heads up if you plan on connecting them at the ignition switch. If the green/red is only going out to the alternator, you can remove this off the ignition switch and connect it to any switched circuit out of the fuse block.

 

[DirtDonk]

I absolutely hate that this is so confusing for me.

I hear ya. Hang in there though, you'll get through it. Either with our help, or after you have that "Eureka! moment" when the Ford lightbulb comes on and it all becomes clear to you.

If I wire it like this, will I have the problem you’re talking about?.

Yes. With the Black w/green wire handling the MSD box, it's going to be on with the key in ACC as well as ON. Not really a good thing.
Change the ignition back to one of the on in RUN only and you should be good.

This is a painless fuse panel only.

Which part number panel? As Eric mentioned, it might not be compatible unless you break the buss-bar into two discrete sections you can then control by the different wires.
If that's possible to do to this box.

From my ignition I have the following:

Black/yellow – Constant 12v. Solenoid to ignition with 60 amp fuse

No problem there in theory, but you really don't want to be running all that power through the switch. I could be wrong, and someone will correct me if so, but I don't think the stock ignition switch was designed to handle 60 amps of current through it.
Maybe fuse it for 30, and see how it goes?

Black/Green – 12v to panel in run and ACC

No prob. if you can separate the halves of the box as mentioned above, and run the ignition off of something other than the Black w/green circuit.

Green/Red – 12v in Run. Ignition to Alternator. I was going to combine this with my choke and run it to the switched side of the panel. Is this what you’re talking about? Better to leave it the way it is?

Ok for the alt and choke, but put the ignition box on it too, and you should be good. Or better yet, get cleaner power to the ignition by putting a relay in the line before the MSD box.

Red/Blue – 12v in Start. Capped off because it went to the old ignition. I’m running MSD now

Sounds ok from here.

Red/Blue – 12v in Start. Ignition to Solenoid

Good to go here as well.

Red/Green – 12v in Run. Not sure about this one yet.

That's the one you want to be powering half of your fuse panel. But since it's so small, and really doesn't have the capacity to run a whole slew of on-demand items with the key (in case you're thinking about adding accessories that is) maybe run it to a relay first, then from the relay power the fuse panel from the battery. Basically getting full power with the key, without running all the power through the ignition switch.

Hope that's not too vague and confuzzling.
Happy tracing (wire-wise) to you.

Paul

 

[JSmall]

Yes. With the Black w/green wire handling the MSD box, it's going to be on with the key in ACC as well as ON. Not really a good thing.
Change the ignition back to one of the on in RUN only and you should be good.

If I keep the Green/Red (12v in Run) wire running from the ignition to the alternator and splice the MSD power wire into it, will that be better?

Which part number panel? As Eric mentioned, it might not be compatible unless you break the buss-bar into two discrete sections you can then control by the different wires.
If that's possible to do to this box.

http://www.painlesswiring.com/Manuals/30004.pdf

10 constant and 10 switched

No problem there in theory, but you really don't want to be running all that power through the switch. I could be wrong, and someone will correct me if so, but I don't think the stock ignition switch was designed to handle 60 amps of current through it.
Maybe fuse it for 30, and see how it goes?

Correct me if I’m wrong, but isn’t the stock ignition wired the same way? Unless I’m looking at it wrong….highly possible, all the 3g wiring diagrams I have found show the Black/Yellow (Constant 12v) wire running from the B+ side of the solenoid to the ignition with a fuse between.

No prob. if you can separate the halves of the box as mentioned above, and run the ignition off of something other than the Black w/green circuit.

See above. Not sure if that is possible

Ok for the alt and choke, but put the ignition box on it too, and you should be good. Or better yet, get cleaner power to the ignition by putting a relay in the line before the MSD box.

See above. I think I have it wired this way now. Not sure how to wire relays, but if they are necessary, I will figure it out.

That's the one you want to be powering half of your fuse panel. But since it's so small, and really doesn't have the capacity to run a whole slew of on-demand items with the key (in case you're thinking about adding accessories that is) maybe run it to a relay first, then from the relay power the fuse panel from the battery. Basically getting full power with the key, without running all the power through the ignition switch.

One of these days I might be able to understand what you just said

I really appreciate the help with this. Until I get everything figured out, I will not be starting the rewire process. I hope to be driving this thing before the summer is over, but at this point I'm not sure if that will happen. I was going to buy a complete harness, but didn't want to hack up a new harness for the 3g and MSD installs.