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

[JSmall]

Do my assumptions above sound correct?

Thanks

 

[JSmall]

Made some progress today.

From the suggestions in this post I'm going to keep the MSD and choke on a Run only circuit with an inline fuse. What amp fuse? Also keeping the green/red going from the alternator to a run only terminal on the switch. All of those will be run seperate from the fuse box. That is correct?

What I'm still having any issue with is the 12v going to the ignition. I bought an inline 60 amp fuse for the 10g wire going from the solenoid to the switch. Currently the black/yellow wire with a small yellow wire jumper going to the ignition switch. I would like to run a new 10g wire from the solenoid, through the 60 amp fuse to the ignition switch. How can I hook the 10g wire to the ignition switch without using the smaller yellow wire that is currently there?

 

[DirtDonk]

Hey there. Sorry I missed the notifications and haven't been back.
I'm on the way out right now, but will check your reply as soon as I get back to see if I have any suggestions.
Lookin' good otherwise! I like the weather-resistant box inside a weather resistant box scenario.
That looks like the fuse box I have in this 10140 kit I've got sitting here. Nice piece. Hmmm, I thought hat did have two separate sections like you were saying?

Just realized your last post was from the 19th! Yikes, you might already be done with the job. How's it going?

OK, off to 1/2 price day at PNP!

Paul

 

[JSmall]

Hey there. Sorry I missed the notifications and haven't been back.
I'm on the way out right now, but will check your reply as soon as I get back to see if I have any suggestions.
Lookin' good otherwise! I like the weather-resistant box inside a weather resistant box scenario.
That looks like the fuse box I have in this 10140 kit I've got sitting here. Nice piece. Hmmm, I thought hat did have two separate sections like you were saying?

Just realized your last post was from the 19th! Yikes, you might already be done with the job. How's it going?

OK, off to 1/2 price day at PNP!

Paul

Thanks for getting back to me. I haven't made any progress since my last pictures and posts. I've been out of town so no progress.

The box does have two sides, constant and switched. From my posts above I made a few changes and I'm wanting to make sure I'm on the right track.

Thanks

 

[DirtDonk]

Quote:Originally Posted by DirtDonk View Post
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?.

That should work. Shame to have to splice of course, but it should be fine. With all that available space in the fuse box, it would be nice to run them both from their own circuits on the "keyed" side, rather than straight from the switch.
No reason to change what you're working with though. Just sayin'

Quote:Originally Posted by DirtDonk View Post
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.

Perfect. Just like the one I was looking at earlier. Nice box.

Quote:Originally Posted by DirtDonk View Post
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..

Not quite. In the stock situation, only those few items that have are controlled by the switch, actually get power through the switch. The other items, including some of the heaviest loads, have their own connections separate from the switch.
Things like ALL the lights, get tapped directly into the Black w/yellow wire. Maybe that's the extent of it, but even if so, then that's quite a bit that does not go through the switch. Headlights, instrument/convenience lights, tail lights, brake lights, hazards, signals and running lights, all get power from the headlight switch, which is powered directly by the battery.

And speaking of direct-from-battery loads... Are the large Red and Black wires from your MSD box hooked directly to the battery somehow?
Only the small wires get switched power. So, if you have your lights, MSD main power, and whatever else does not need a key, hooked to that side of the box that's not running off of the ignition switch, you should be good to go.

For a load, accessories like radio, heater, ignition, starter relay, probably only use a total of maybe 30 amps when they're all on. Hence the lower rating on the fuse and the need for not overloading the stock switch.
I'll bring up the relays again later.

Quote:Originally Posted by DirtDonk View Post
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.

There might be an overall solution coming. See more comments about relays below.

Quote:Originally Posted by DirtDonk View Post
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..

Quote:Originally Posted by DirtDonk View Post
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.

Hah! Yeah, I know. I talk too much, but relays are a strange subject until the light comes on in the brain in an "Ah Ha!!!!" moment.
I'm going to start another post below with some suggestions about using a relay or two, and how to wire them up.

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..

No worries. You might consider doing the new harness at the same time, but you're already half way there with a new fuse box, and any pre-made harness is going to have it's own fuse box that would just be duplicating what you're doing now.
You've got a great setup started, and have already put some money into it, but it might just still be worth sitting back and looking at what you want to do overall. That way you can decide now whether you're going to stay with all the old wires, or start fresh with all new.
If all new, stop now before you pull any more hair out and get a harness.

If not, and you think your stock wires are still in serviceable shape, and you're not going to do a whole harness for a few years, then keep on truckin' in the direction you're taking now.

Paul

 

[DirtDonk]

Ok, relays...
Think of a relay as just a simple "heavy-duty remote switch" and it might be easier to work with. You use your original switches, in this case, the ignition switch, to control the remote switch (the relay) and let the heavier duty relay turn the fuse panel on and off. Instead of running it all from the old ignition switch.
The starter "relay" (what most still call a solenoid) is one such heavy-duty remote switch. Your ignition switch could never control a starter motor, since it pulls enough current to melt your switch. Insert the fender mounted relay in-between though, and you can crank a starter with no ill effects on anything.

What I was getting at in the previous post, was that if you get a sufficiently sized relay, say 40 amps rated (which is a very common and inexpensive size), and use it to turn the switched side of the fuse panel on and off, you only need one wire to the fuse panel from the key, and won't have to worry about your ignition switch failing early due to hard use.

Is that making any sense? If so, I can run you through how to do it. Basically though, you're just going to run the Black w/green wire to the relay, then to the fuse box. The Red w/blue wire can still go straight from the switch to the starter relay, and the Red w/green can still work the ignition if you want. But all the rest is controlled by the new fuse box and the new relay.

Sound like it's worth a try?

Paul

 

[JSmall]

That should work. Shame to have to splice of course, but it should be fine. With all that available space in the fuse box, it would be nice to run them both from their own circuits on the "keyed" side, rather than straight from the switch.
No reason to change what you're working with though. Just sayin'

This is where I think I'm getting confused or I'm getting mixed info. In earlier posts I was going to run the MSD, choke, and alternator to the "keyed" side of the new fuse box, but was told it would be better to run it off the "Run" side of the switch because the MSD, choke, and alternator would be "hot" when the key was in ACC if I wired it to the "switched" side of the fuse box. I would rather run it off the fuse box if that will not be an issue.

Not quite. In the stock situation, only those few items that have are controlled by the switch, actually get power through the switch. The other items, including some of the heaviest loads, have their own connections separate from the switch.
Things like ALL the lights, get tapped directly into the Black w/yellow wire. Maybe that's the extent of it, but even if so, then that's quite a bit that does not go through the switch. Headlights, instrument/convenience lights, tail lights, brake lights, hazards, signals and running lights, all get power from the headlight switch, which is powered directly by the battery.

I plan to run any wire that was connected to the Black/Yellow wire, back to the new fuse box.

And speaking of direct-from-battery loads... Are the large Red and Black wires from your MSD box hooked directly to the battery somehow?
Only the small wires get switched power. So, if you have your lights, MSD main power, and whatever else does not need a key, hooked to that side of the box that's not running off of the ignition switch, you should be good to go.

That is how I have it wired right now. The MSD signal wire will be run off the "switched" side of the box or the "Run" side of the ignition depending on what the best way to do it is. The main power wire for the MSD is hooked to the "constant" lug on the new fuse box. The same lug that gets power from the battery. The ground wire will be ground to the frame.

Hah! Yeah, I know. I talk too much, but relays are a strange subject until the light comes on in the brain in an "Ah Ha!!!!" moment.
I'm going to start another post below with some suggestions about using a relay or two, and how to wire them up.

I'll read up on relays a little more. I understand the need for them, but I was trying to wire the Bronco the same as stock so I didn't think they would be needed until I added things that required them...fuel pump, lights...

No worries. You might consider doing the new harness at the same time, but you're already half way there with a new fuse box, and any pre-made harness is going to have it's own fuse box that would just be duplicating what you're doing now.
You've got a great setup started, and have already put some money into it, but it might just still be worth sitting back and looking at what you want to do overall. That way you can decide now whether you're going to stay with all the old wires, or start fresh with all new.
If all new, stop now before you pull any more hair out and get a harness.

If not, and you think your stock wires are still in serviceable shape, and you're not going to do a whole harness for a few years, then keep on truckin' in the direction you're taking now.

Paul

I repaired the stock wires that needed to be repaired so I think I'm good to go now. I would have purchased a new harness if the Bronco was stock. With the MSD and 3g alternator I thought I would need to modify the brand new harness so I chose not to go that route. I guess I could have gone either way.

I think I'm making some good progress and I'm starting to understand the wiring. I'll be working on it again on Saturday so I have a few days to get this figured out.

Thanks

 

[DirtDonk]

This is where I think I'm getting confused or I'm getting mixed info. In earlier posts I was going to run the MSD, choke, and alternator to the "keyed" side of the new fuse box, but was told it would be better to run it off the "Run" side of the switch because the MSD, choke, and alternator would be "hot" when the key was in ACC if I wired it to the "switched" side of the fuse box. I would rather run it off the fuse box if that will not be an issue.

Sorry, you're right. I'm getting screwed up from not paying strict attention.
Yes, if your switched side of the fuse box is off the Black w/green ACC wire, then yes, all of your switched stuff is going to be run in either position (not good) and all of it through the switch (also not good).

So do what we discussed previously and hook the "RUN" only stuff direct to the switch, and run the other stuff, that can be on any time (radio, heater, etc) through the fuse box off the Black w/green wire.

I was getting ahead of myself with the relay and all, just zeroing in on trying to take some of the load off of the stock ignition switch, and forgot that I was talking about stuff that has to run in two separate states. RUN and ACC.

So it's ok to run those things through the key, but as I mentioned previously, if you add many more things, especially heavy load items (such as a BIG stereo, or a BIG bank of lights, then I still stand by the recommended use of a relay to power the bulk of the load.

Again, sorry for the confusion. Entirely my fault for losing track of the setup. Not enough sleep I guess? Sounds like a good excuse anyway... ;D

I plan to run any wire that was connected to the Black/Yellow wire, back to the new fuse box.

Ok, sounds reasonable. As long as they're on the constant-hot side, you should be good.

That is how I have it wired right now. The MSD signal wire will be run off the "switched" side of the box or the "Run" side of the ignition depending on what the best way to do it is. The main power wire for the MSD is hooked to the "constant" lug on the new fuse box. The same lug that gets power from the battery. The ground wire will be ground to the frame.

RUN side of the switch is best.
All sounds good.

I'll read up on relays a little more. I understand the need for them, but I was trying to wire the Bronco the same as stock so I didn't think they would be needed until I added things that required them...fuel pump, lights...

Not an unreasonable way to do it. I was just thinking about adding one or more now, so you don't have to mess up your nice neat wiring later. And I didn't really know what kind of accessories you did or did not plan to add right now, as you were doing this.
But you're basically correct. As long as you're not running more through the switch than it was designed to handle, you should be ok and I'm just overthinking it for you and making it needlessly complex.
You know, so you don't have to overthink it yourself!

I repaired the stock wires that needed to be repaired so I think I'm good to go now. I would have purchased a new harness if the Bronco was stock. With the MSD and 3g alternator I thought I would need to modify the brand new harness so I chose not to go that route. I guess I could have gone either way.

Good call. Sounds like you're going the right route.

I think I'm making some good progress and I'm starting to understand the wiring. I'll be working on it again on Saturday so I have a few days to get this figured out.

Yep, working on it as extremely as you are doing is the best way to get to understand things.

Good luck. Keep the pics and progress reports coming

Paul

 

[JSmall]

No problem on the mix up. I had to go back and read through the thread to make sure I wasn't going crazy

Lots of info in this thread so it is easy to mix things up. I'm working on the wiring all day Saturday so I should make some good progress. I will post up some pictures and let you know how it goes.

Thanks again and again for all the help.