Additional Fuse Panel

I want to add an aux fuse panel, one hot and one when the key is on, so I can hook up power door locks, trunk, stereo, gauges and other things I might add in the future. For the things I want power when the ignition is on, do all I need to do is run a power wire from the IGN or ACC port on the stock fuse block to the new aux fuse panel? Seems too easy that I feel like I am missing something.

These are the boxes I saw that could be used.

https://www.repairconnector.com/products/4-Slot-Fuse-Block-for-ATO-and-ATC-Blade-Fuses-With-Brass-Terminals.html

https://www.amazon.com/6-Way-Blade-LED-Indicator-Protection/dp/B00QMTAZ1W/ref=pd_cp_263_3?pd_rd_w=JSgUR&pf_rd_p=ef4dc990-a9ca-4945-ae0b-f8d549198ed6&pf_rd_r=9M90444D8PSFDHYDCK23&pd_rd_r=72a27ee5-1eb0-11e9-8739-9941e184f583&pd_rd_wg=o1G4k&pd_rd_i=B00QMTAZ1W&psc=1&refRID=9M90444D8PSFDHYDCK23



Do I need to add relays? These threads talk about adding relays but not sure if I need them.

https://www.chevelles.com/forums/27-electrical-wiring/144237-help-wiring-extra-fuse-panel.html
https://www.chevelles.com/forums/27-electrical-wiring/145904-added-fuse-panel-pics.html

I'm guessing I will need an always hot fuse box for my door locks and trunk. Where is the best place to run the hot wire from? The above threads say to run it from the horn relay but I'm not sure our gen has a horn relay.

thatfnthing - thanks for your suggestions below.

thatfnthing wrote:The first thing to consider when adding something electrical is the expected current draw of the thing you're trying to add.  Your primary options would be:

1. Tap into an existing circuit.  You could get away with this if you are adding something with a very small current draw.  For example, you could simply splice an LED into the instrument panel lamp circuit, especially if you've lowered the normal current drain by switching all the other lamps on the circuit to LEDs.  In this case, you've drastically lowered the possible maximum amount of juice, so there's capacity to spare.

2. Add a new circuit. This will involve exactly what you describe above -- a new feed from the batt/alternator (or ignition switch or existing fuse block) running to an inline fuse or a mini-fuse block.

The next thing to consider is when the thing needs to have power.  If the answer is 'always' (i.e. even with the ignition off), you can run straight from the batt/alternator to the fuse, and then to the device.  If the answer is 'only in run' or 'only in accessory', then you are looking at splicing directly from the appropriate feeds from the ignition switch, then to the fuse, then to the device.

Last thing then is wire gauge.  This will be determined by the total amount of current the circuit is expected to carry for any length of time.  Too small a wire gauge, and the wires will run too hot and introduce too much resistance, which will play hell with electronic devices and sensors.  I tend to go more conservative than the factory, so I use roughly this scale:

1A or less = 20ga
1A to 5A = 18ga
5A to 10A = 16ga
10A to 15A = 14ga
15A to 20A = 12ga
20A to 30A = 10ga

Also be aware that the ground wire will need to be the same gauge as the feed.

And a word of caution: Under no circumstances should anyone just add stuff to an existing factory circuit and put in a larger fuse.  While the fuse will allow the larger amount of current through, the wires were sized according to the original expected load.  Pulling more juice through a wire that's too small will create heat.  LOTS of heat.  Possibly even enough to melt the insulation or wiring, or even start a fire depending on how much current you're trying to stuff through them.

Everything depends on the total draw of what you're planning to add.  Gauges and LEDs draw very little, door locks and trunk release draw a fair amount, but only for an instant, and power windows, seats, and ABS draw a huge amount.  Stereos can run the gamut depending on how loud you want to be.

If it's only a marginal draw you're adding, it technically CAN be as simple as branching a subpanel from one of the existing fusebox ports.  The issue with branching off from the BAT, ACC, or IGN ports is that 1) they already have predetermined fuses (20A, 10A, and 20A respectively) and 2) there are already loads on those circuits that have to be deducted from the fuse amount to see what the remaining capacity is.  And you don't want to push it right to the edge, either.

You will be best served by adding a separate fuse box for each mode: constant hot (BAT) and ignition only (IGN).  This way you can size the wire feed for what you plan to run off of it without having to worry about messing with the cars existing circuits.  If you run the BAT line from the horn relay (yes, you should have one on the firewall to the right of the brake booster), it will be protected by the fusible link that feeds the horn relay, but while you can pull more amps than the fusebox ports would allow, you still can't get SUPER crazy with it because it is also feeding most everything else in the car from the wire between the starter and horn relay.  If you are pulling monster amps, a new line (and fusible link) should be run from the battery or starter.

For IGN, it's slightly more complicated -- you can tap directly into the 12ga PNK or ORN wires coming from the ignition switch (both should be hot in RUN), but again, it's better than the fusebox port but there's still a limit to how crazy you can get.

This is where relays come in.  A relay is simply a small switch that throws a bigger switch.  Rather than tax an existing circuit beyond its capacity, the existing circuit can be used instead just to trip the relay (which draws hardly anything).  The relay then does the heavy lifting and the 'big' switch turns on the power to whatever device is being supplied from a line that might run back to the battery directly.  This is how power seats work (in modern cars anyway) -- a relay is tripped by a small amount of current, and it turns on the main power to the seat motor from a bigger wire.  Relays are super handy, and can be used for all kinds of things, including reversing power (i.e. turning stuff off instead of on) and switching between two devices.  I even use them in my house wiring.  In your case, you could even run a large feed from the battery to both your new subpanels, and a relay put on the IGN one so that the car's ignition switch turns on the flow of power to that panel, but the power actually comes from the battery.

Sorry to be long winded.  

So step #1 is: what devices do you want to add, when do they need to have power, and what does each draw?


As an aside, your fuse box appears to have a considerable amount of corrosion.  Does everything work properly?  I know mine had less and it still gave me all kinds of headaches.  This might be a good time to consider rewiring the whole car and adding your additional circuits in the process...

I just redid the wiring on a friends 68 camaro with a kit from one of the major suppliars of wiring kits( i Think painless wiring but not sure) anyways it was Real easy to work with and had all modern fuses and all modern accessories circuts you could ever wish for including power Windows/ doors, aircon, stereo, ekstra fans etc etc. I took me 3 weekends to rewire the whole car, and all is up to modern standarts now whatever accessorie he wants to ad. And no more Electric Gremlins and dim lights and brittle wiring. 

I redid my own with complete new wiring from from elcamino store, its all original style and works like it should. However i wish i had knows about the modern wiring kits, because it is Way better without he modern fuses and ekstra circuts. So maybe it would be better to rewire the whole thing, its really not that difficult when you get going and take your time. Regards Henrik.

Great information, thank you! I will need to read, re-read and probably read again before I can comprehend everything.

That is not my fuse box, I took the pic from another thread. It was easier then me trying to take a picture of mine.
http://www.g3gm.com/t9677-universal-wiring-harnesses

Oh, yes, I see that was SonOfTheGrim's. Frankly, it amazed me it worked at all. I wonder how he ever made out.

Feel free to hit me with any Q if anything doesn't make sense or needs more explanation.  Happy to elaborate!

I am going to try and install the additional fuses at the end of the month.

I ordered 12 gauge wire, 60/80 amp relays and fuse able links to run the new power wires to the switched and always hot fuse panels. Any issues with these?

After looking under the hood, I do not have a horn relay on the firewall. I looked at Rockauto and the '73 and earlier are a different than the '74 and later years. Should I run a wire directly from the battery and splice it to run one wire to the switched fuse box and one to the always hot? Is there a better spot to tap into?

This is how I was planning on wiring the switched panel. Wire #86 will come from one of the open acc spots on the factory fuse panel.  


'73 and earlier horn relay


'74 and later horn relay

Here's an idea, it will give you a cleaner look and may eliminate another issue if you have headers. You can add a ford starter solenoid and connect a jumper wire from the S terminal of your starter to the B+ on the starter. Connect a cable to your starter from the Ford type solenoid and connect your battery cable to the Ford type solenoid. Then you can connect the power wire normally on your starter to the solenoid and run your power for the fuse panel them there also. Just a thought. We did this on stock cars so you don't have a a wire that's always hot beside your header.

Hawk03 wrote:I ordered 12 gauge wire, 60/80 amp relays and fuse able links to run the new power wires to the switched and always hot fuse panels. Any issues with these?

You only need the relay for the switched panel.  The constant hot is just a straight line from the batt to the panel.  Fusible links for both.  What's 60/80?  Continuous versus surge?  Got a link to it so I can eyeball it?  Whichever number is the 'continuous', that's your upper limit to how much you can draw through that panel -- all accessories combined.  And a good rule of thumb is only to go to 2/3 of that limit when you add up all the draws.

Hawk03 wrote:After looking under the hood, I do not have a horn relay on the firewall. I looked at Rockauto and the '73 and earlier are a different than the '74 and later years.

I don't see how you can't have one.  Your horn works, doesn't it?  And hand-to-God, ALL the circuits feed from there to the fuse panel and everywhere else.  So if you have the main feed from the starter, where does the other end go?  It has to meet all the other feed wires somewhere...

Hawk03 wrote:Should I run a wire directly from the battery and splice it to run one wire to the switched fuse box and one to the always hot? Is there a better spot to tap into?

Battery is easiest.  I have most of my connections there (including my alternator feed -- GM used the starter as a distribution point because it allowed them to save a couple feet of wire per unit, it's actually a terrible place for that), though if you wanted to get fancy you could actually pick up a distribution block from a factory GM car in the boneyard and mount it to your inner fender like they did later on as a load center.  Looks cooler and is more organized, but it's also more work.

I'm going to be conservative on wire gauge here, especially since I don't know how much you're planning to run off these.  So if you are using 12ga wire, I would run a separate line for each.  If you go to 10ga you can simply run one and split it to each.

Hawk03 wrote:This is how I was planning on wiring the switched panel. Wire #86 will come from one of the open acc spots on the factory fuse panel.

Close -- use the IGN port to feed #86.  ACC is hot in accessory mode.  Just so we're on the same page, the 'device' in the diagram is your switched panel, the ground from there represents all your accessories (not an 'actual' ground, each accessory will have its own), and the 'fuse' is actually your FL.  The 30 and 87 wires should be 10-12ga, the 86 and 85 wires only need to be 18ga.

That's for the switched panel.  For the constant hot, it's a lot simpler: BATT--->FL--->Panel

Flywheel wrote:Here's an idea, it will give you a cleaner look and may eliminate another issue if you have headers. You can add a ford starter solenoid and connect a jumper wire from the S terminal of your starter to the B+ on the starter. Connect a cable to your starter from the Ford type solenoid and connect your battery cable to the Ford type solenoid. Then you can connect the power wire normally on your starter to the solenoid and run your power for the fuse panel them there also. Just a thought. We did this on stock cars so you don't have a a wire that's always hot beside your header.

Yep, this goes along with the fender distribution block idea. It's a better layout, easier to manage, and away from headers and weather. But GM was cheap back then, and a few feet of wire saved per unit across a million units added up to real $$$.

Thanks guys. This is good stuff. I want to make sure everything will connected correctly and not burn the car down.

thatfnthing wrote:

Hawk03 wrote:I ordered 12 gauge wire, 60/80 amp relays and fuse able links to run the new power wires to the switched and always hot fuse panels. Any issues with these?

You only need the relay for the switched panel.  The constant hot is just a straight line from the batt to the panel.  Fusible links for both.  What's 60/80?  Continuous versus surge?  Got a link to it so I can eyeball it?  Whichever number is the 'continuous', that's your upper limit to how much you can draw through that panel -- all accessories combined.  And a good rule of thumb is only to go to 2/3 of that limit when you add up all the draws.

"relay is rated to handle 80 amps of load at 12V DC in the normally open position, and 60 amps of load at 12V DC in the normally closed position."
Below is the relay.
https://www.amazon.com/gp/product/B01NCA6CAB/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
Fuse able link
https://www.amazon.com/gp/product/B017BAF7GS/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

thatfnthing wrote:

Hawk03 wrote:After looking under the hood, I do not have a horn relay on the firewall. I looked at Rockauto and the '73 and earlier are a different than the '74 and later years.

I don't see how you can't have one.  Your horn works, doesn't it?  And hand-to-God, ALL the circuits feed from there to the fuse panel and everywhere else.  So if you have the main feed from the starter, where does the other end go?  It has to meet all the other feed wires somewhere...

My horn does not work but I thought it might be due to the connection in the steering wheel not connected correctly. Its possible I'm missing it. I don't remember if there was one on my old body's firewall. I will search some more.

thatfnthing wrote:

Hawk03 wrote:Should I run a wire directly from the battery and splice it to run one wire to the switched fuse box and one to the always hot? Is there a better spot to tap into?

Battery is easiest.  I have most of my connections there (including my alternator feed -- GM used the starter as a distribution point because it allowed them to save a couple feet of wire per unit, it's actually a terrible place for that), though if you wanted to get fancy you could actually pick up a distribution block from a factory GM car in the boneyard and mount it to your inner fender like they did later on as a load center.  Looks cooler and is more organized, but it's also more work.

I'm going to be conservative on wire gauge here, especially since I don't know how much you're planning to run off these.  So if you are using 12ga wire, I would run a separate line for each.  If you go to 10ga you can simply run one and split it to each.

Thanks makes sense. I was going to run separate from the horn relay but I need to find it first,lol. I did order a busbar with the thought of running a wire from the battery to the busbar then running a separate wires to the individual fuse panels. I will order 10ga wire and fuses links as well.

https://www.amazon.com/gp/product/B017LM0KEA/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

I'm not going to go too crazy on what I am going to install. Switched - Radio, LED DRL's, gauges. Always on - radio, door locks, truck release.

thatfnthing wrote:

Hawk03 wrote:This is how I was planning on wiring the switched panel. Wire #86 will come from one of the open acc spots on the factory fuse panel.

Close -- use the IGN port to feed #86.  ACC is hot in accessory mode.  Just so we're on the same page, the 'device' in the diagram is your switched panel, the ground from there represents all your accessories (not an 'actual' ground, each accessory will have its own), and the 'fuse' is actually your FL.  The 30 and 87 wires should be 10-12ga, the 86 and 85 wires only need to be 18ga.

That's for the switched panel.  For the constant hot, it's a lot simpler: BATT--->FL--->Panel

Got it. Thanks. IGN it is. I think the relays in the above link have 12ga for 30 and 87.

Hawk03 wrote:"relay is rated to handle 80 amps of load at 12V DC in the normally open position, and 60 amps of load at 12V DC in the normally closed position."
Below is the relay.
https://www.amazon.com/gp/product/B01NCA6CAB/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

Okay, then your max upper limit is 80A continuous, but rule of thumb is try not to exceed 2/3 of that.  From your to-do list, you're not going to get anywhere near there.    Those should work fine, but I would verify that the 30 and 87 wires actually have 12ga wire.  Sometimes they lie, in which case you should replace those.  I always do anyway, to make sure they match gauge and the wire color in my circuit diagram.

Hawk03 wrote:Fuse able link
https://www.amazon.com/gp/product/B017BAF7GS/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

Those are inline fuses, not fusible links.  These are fusible links :

https://www.amazon.com/Pico-8125PT-Gauge-Fusible-Package/dp/B004BT6NZ2/ref=sr_1_1?crid=MB6ZINUSA02R&keywords=fusible+link+14+gauge&qid=1575477337&s=automotive&sprefix=fusible+link+14%2Cautomotive%2C135&sr=1-1

https://www.amazon.com/Dorman-Help-85620-Gauge-Fusible/dp/B000COD0TW/ref=sr_1_2?crid=MB6ZINUSA02R&keywords=fusible+link+14+gauge&qid=1575477337&s=automotive&sprefix=fusible+link+14%2Cautomotive%2C135&sr=1-2

Basically, a FL is just a wire 4 sizes smaller than the wire you're trying to protect (i.e. the above are 14ga to protect a 10ga circuit, a 16ga FL would be used for 12ga wire), but it's supposed to have much thicker insulation.  The idea is that the actual feed wire from the power source (battery) up to the first fuse is vulnerable to a short.  Everything after the fuse panel is protected by the fuses, but if this feed wire should short to ground for any reason, you're looking at a fire because it has no protection.  This is where the FL comes in. The FL is supposed to be the first thing connected to the power source, and then the main wire to wherever is spliced onto the end.  This way, if that main wire should short for any reason before the fuse panel, the FL will burn up inside its casing and sever the connection.  This way you avoid a catastrophe.

Now, all that said, not all FL's have thick enough insulation and I have seen them blow right through it, in which case the FL itself is now a hot wire looking for a ground.  So get one with extra thick insulation if possible.  Some kind of external wrap couldn't hurt, either, and make sure everything is secure from vibration, moisture, and heat sources.  Again, this is why the starter absolutely sucks as a distribution point -- you have all 3 of those problems in that location.

Hawk03 wrote:My horn does not work but I thought it might be due to the connection in the steering wheel not connected correctly. Its possible I'm missing it. I don't remember if there was one on my old body's firewall. I will search some more.

As you look at the M/C from the front of the car, it should be to the right mounted to the firewall, and it will have a screw post sticking out with a crap ton of wires attached to it -- these are the FL's to the fuse panel and the rest of the car.  One will be the primary feed from the starter.  If any of the electrics in the car work, they all lead back here -- unless someone completely rewired the car to eliminate it.

Hawk03 wrote:I did order a busbar with the thought of running a wire from the battery to the busbar then running a separate wires to the individual fuse panels. I will order 10ga wire and fuses links as well.

https://www.amazon.com/gp/product/B017LM0KEA/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

That will work, and it's nice that it has a cover, but for complete protection you would like one that completely seals the incoming wires against moisture.  Or, once all the wires are installed, give all of the connections a liberal coat of liquid electrical tape.

Hawk03 wrote:I'm not going to go too crazy on what I am going to install. Switched - Radio, LED DRL's, gauges. Always on - radio, door locks, truck release.

In that case you will have plenty of room for growth.  The only caveat I can think of is that if the primary power for the radio is only when the IGNition is on, you will not be able to play it with the key in ACCessory mode.

thatfnthing wrote:
Okay, then your max upper limit is 80A continuous, but rule of thumb is try not to exceed 2/3 of that.  From your to-do list, you're not going to get anywhere near there.    Those should work fine, but I would verify that the 30 and 87 wires actually have 12ga wire.  Sometimes they lie, in which case you should replace those.  I always do anyway, to make sure they match gauge and the wire color in my circuit diagram.

Thanks for all of your answers and comments. I will verify the gauge and replace if needed.

thatfnthing wrote:
Those are inline fuses, not fusible links.  These are fusible links :

https://www.amazon.com/Pico-8125PT-Gauge-Fusible-Package/dp/B004BT6NZ2/ref=sr_1_1?crid=MB6ZINUSA02R&keywords=fusible+link+14+gauge&qid=1575477337&s=automotive&sprefix=fusible+link+14%2Cautomotive%2C135&sr=1-1

https://www.amazon.com/Dorman-Help-85620-Gauge-Fusible/dp/B000COD0TW/ref=sr_1_2?crid=MB6ZINUSA02R&keywords=fusible+link+14+gauge&qid=1575477337&s=automotive&sprefix=fusible+link+14%2Cautomotive%2C135&sr=1-2

Basically, a FL is just a wire 4 sizes smaller than the wire you're trying to protect (i.e. the above are 14ga to protect a 10ga circuit, a 16ga FL would be used for 12ga wire), but it's supposed to have much thicker insulation.  The idea is that the actual feed wire from the power source (battery) up to the first fuse is vulnerable to a short.  Everything after the fuse panel is protected by the fuses, but if this feed wire should short to ground for any reason, you're looking at a fire because it has no protection.  This is where the FL comes in.  The FL is supposed to be the first thing connected to the power source, and then the main wire to wherever is spliced onto the end.  This way, if that main wire should short for any reason before the fuse panel, the FL will burn up inside its casing and sever the connection.  This way you avoid a catastrophe.

Now, all that said, not all FL's have thick enough insulation and I have seen them blow right through it, in which case the FL itself is now a hot wire looking for a ground.  So get one with extra thick insulation if possible.  Some kind of external wrap couldn't hurt, either, and make sure everything is secure from vibration, moisture, and heat sources.  Again, this is why the starter absolutely sucks as a distribution point -- you have all 3 of those problems in that location.

This is very good to know. I didn't realize there was a difference or what an fusible link was. I ordered some and will install with the wiring. When we've installed amps in the past, we installed one of these on the power wire. I think the fusible link seems more safe guard then just an inline fuse.

https://www.amazon.com/Rockford-Fosgate-Single-Line-Holder/dp/B006T2N2LM/ref=pd_cp_107_1/142-4460349-3545956?_encoding=UTF8&pd_rd_i=B006T2N2LM&pd_rd_r=58a980b2-eeb2-454e-b37c-65668dac11b0&pd_rd_w=Vm9BH&pd_rd_wg=coR81&pf_rd_p=0e5324e1-c848-4872-bbd5-5be6baedf80e&pf_rd_r=HJJKH9WSRPNPB6TEFXMR&refRID=HJJKH9WSRPNPB6TEFXMR&th=1

thatfnthing wrote:As you look at the M/C from the front of the car, it should be to the right mounted to the firewall, and it will have a screw post sticking out with a crap ton of wires attached to it -- these are the FL's to the fuse panel and the rest of the car.  One will be the primary feed from the starter.  If any of the electrics in the car work, they all lead back here -- unless someone completely rewired the car to eliminate it.

I've been the only person who has touched the wiring, not that thats a good thing. I could have forgot to install the relay when I transferred the wiring from my car to the new car. Looking at other people's engine bay, I see where the horn relay should be. I will need to figure out which wires attach to it and install a new one. I do have a new engine bay wiring harness and will hopefully install that this winter as well.

thatfnthing wrote:That will work, and it's nice that it has a cover, but for complete protection you would like one that completely seals the incoming wires against moisture.  Or, once all the wires are installed, give all of the connections a liberal coat of liquid electrical tape.

Thanks, I will seal it, ordered liquid tape as well.

thatfnthing wrote:In that case you will have plenty of room for growth.  The only caveat I can think of is that if the primary power for the radio is only when the IGNition is on, you will not be able to play it with the key in ACCessory mode.

Thanks. I should be okay on the additional accessories. I'll probably install a USB port or two to charge my phone. I want to install your power mirror conversion and possible power windows as well in the future. I have to remember its a car I only drive a few hundred miles a year so I don't need a lot.  
I will need to keep the radio hooked up to ACC.

thatfnthing wrote:
Okay, then your max upper limit is 80A continuous, but rule of thumb is try not to exceed 2/3 of that.  From your to-do list, you're not going to get anywhere near there.    Those should work fine, but I would verify that the 30 and 87 wires actually have 12ga wire.  Sometimes they lie, in which case you should replace those.  I always do anyway, to make sure they match gauge and the wire color in my circuit diagram.

Thanks for all of your answers and comments. I will verify the gauge and replace if needed.

thatfnthing wrote:
Those are inline fuses, not fusible links.  These are fusible links :

https://www.amazon.com/Pico-8125PT-Gauge-Fusible-Package/dp/B004BT6NZ2/ref=sr_1_1?crid=MB6ZINUSA02R&keywords=fusible+link+14+gauge&qid=1575477337&s=automotive&sprefix=fusible+link+14%2Cautomotive%2C135&sr=1-1

https://www.amazon.com/Dorman-Help-85620-Gauge-Fusible/dp/B000COD0TW/ref=sr_1_2?crid=MB6ZINUSA02R&keywords=fusible+link+14+gauge&qid=1575477337&s=automotive&sprefix=fusible+link+14%2Cautomotive%2C135&sr=1-2

Basically, a FL is just a wire 4 sizes smaller than the wire you're trying to protect (i.e. the above are 14ga to protect a 10ga circuit, a 16ga FL would be used for 12ga wire), but it's supposed to have much thicker insulation.  The idea is that the actual feed wire from the power source (battery) up to the first fuse is vulnerable to a short.  Everything after the fuse panel is protected by the fuses, but if this feed wire should short to ground for any reason, you're looking at a fire because it has no protection.  This is where the FL comes in.  The FL is supposed to be the first thing connected to the power source, and then the main wire to wherever is spliced onto the end.  This way, if that main wire should short for any reason before the fuse panel, the FL will burn up inside its casing and sever the connection.  This way you avoid a catastrophe.

Now, all that said, not all FL's have thick enough insulation and I have seen them blow right through it, in which case the FL itself is now a hot wire looking for a ground.  So get one with extra thick insulation if possible.  Some kind of external wrap couldn't hurt, either, and make sure everything is secure from vibration, moisture, and heat sources.  Again, this is why the starter absolutely sucks as a distribution point -- you have all 3 of those problems in that location.

This is very good to know. I didn't realize there was a difference or what an fusible link was. I ordered some and will install with the wiring. When we've installed amps in the past, we installed one of these on the power wire. I think the fusible link seems more safe guard then just an inline fuse.

https://www.amazon.com/Rockford-Fosgate-Single-Line-Holder/dp/B006T2N2LM/ref=pd_cp_107_1/142-4460349-3545956?_encoding=UTF8&pd_rd_i=B006T2N2LM&pd_rd_r=58a980b2-eeb2-454e-b37c-65668dac11b0&pd_rd_w=Vm9BH&pd_rd_wg=coR81&pf_rd_p=0e5324e1-c848-4872-bbd5-5be6baedf80e&pf_rd_r=HJJKH9WSRPNPB6TEFXMR&refRID=HJJKH9WSRPNPB6TEFXMR&th=1

thatfnthing wrote:As you look at the M/C from the front of the car, it should be to the right mounted to the firewall, and it will have a screw post sticking out with a crap ton of wires attached to it -- these are the FL's to the fuse panel and the rest of the car.  One will be the primary feed from the starter.  If any of the electrics in the car work, they all lead back here -- unless someone completely rewired the car to eliminate it.

I've been the only person who has touched the wiring, not that thats a good thing. I could have forgot to install the relay when I transferred the wiring from my car to the new car. Looking at other people's engine bay, I see where the horn relay should be. I will need to figure out which wires attach to it and install a new one.

thatfnthing wrote:That will work, and it's nice that it has a cover, but for complete protection you would like one that completely seals the incoming wires against moisture.  Or, once all the wires are installed, give all of the connections a liberal coat of liquid electrical tape.

Thanks, I will seal it, ordered liquid tape as well.

thatfnthing wrote:In that case you will have plenty of room for growth.  The only caveat I can think of is that if the primary power for the radio is only when the IGNition is on, you will not be able to play it with the key in ACCessory mode.

Thanks. I should be okay on the additional accessories. I'll probably install a USB port or two to charge my phone. I want to install your power mirror conversion and possible power windows as well in the future. I have to remember its a car I only drive a few hundred miles a year so I don't need a lot.  
I will need to keep the radio hooked up to ACC.[/quote]

Hawk03 wrote:This is very good to know. I didn't realize there was a difference or what an fusible link was. I ordered some and will install with the wiring. When we've installed amps in the past, we installed one of these on the power wire. I think the fusible link seems more safe guard then just an inline fuse.

https://www.amazon.com/Rockford-Fosgate-Single-Line-Holder/dp/B006T2N2LM/ref=pd_cp_107_1/142-4460349-3545956?_encoding=UTF8&pd_rd_i=B006T2N2LM&pd_rd_r=58a980b2-eeb2-454e-b37c-65668dac11b0&pd_rd_w=Vm9BH&pd_rd_wg=coR81&pf_rd_p=0e5324e1-c848-4872-bbd5-5be6baedf80e&pf_rd_r=HJJKH9WSRPNPB6TEFXMR&refRID=HJJKH9WSRPNPB6TEFXMR&th=1

Technically, you could make those work. The only concern (and this is admittedly minimal) would be that there's the remote possibility for a short in the wire that feeds the fuse. Everything after the fuse is protected, but that one little length of wire could someday have an issue. Highly unlikely, but that's why the first thing off the power source is usually a FL. The only other issue might be that if you use a bunch of inline fuses, it might be a PITA trying to track it down if one blows.

Hawk03 wrote:Thanks, I will seal it, ordered liquid tape as well.

Home Depot and Lowes have it also.

Hawk03 wrote:Thanks. I should be okay on the additional accessories. I'll probably install a USB port or two to charge my phone. I want to install your power mirror conversion and possible power windows as well in the future. I have to remember its a car I only drive a few hundred miles a year so I don't need a lot.  
I will need to keep the radio hooked up to ACC.

USB typically draws .5A, and the mirrors draw next to nothing. I'd put both those on the constant hot panel. The windows will draw a bunch of amps, and should be on the switched panel, and use 12ga wire to feed the motors. For the radio, if you have and/or are salvaging the original harness, maybe just hook the radio's primary hot to the existing factory circuit -- it should be hot in IGN and ACC.

Good luck, and post some photos!

Thanks again for the info. I started the install and was able to make the switched panel work! I ran a 14ga fusible link from the battery to a 10ga wire through the fire wall directly to the relay. I am going to get a different post to splice the wire so one wire can go to the switched panel and one to the always hot panel. I need to get smaller fuse panels as well so I can install in the passenger side kick panel. Below is it mocked up with the current setup.

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I also found the horn relay which is not on the firewall. It is part of the harness in the interior and takes the three prong relay that is in the pic in the previous post. The wiring harnesses must have changed for the 76/77 years. I switched out the horns and it works although it only works when I take off the steering wheel cover and manually touch the button with metal. I think the button I installed in the column is too short to touch the metal plate. I have the sport steering wheel.

Wiring diagram.
https://imgur.com/a/QT5V0Lj

The sport steering wheel does use a different pin/spring A$$'y.

Hawk03 wrote:Thanks again for the info. I started the install and was able to make the switched panel work! I ran a 14ga fusible link from the battery to a 10ga wire through the fire wall directly to the relay. I am going to get a different post to splice the wire so one wire can go to the switched panel and one to the always hot panel. I need to get smaller fuse panels as well so I can install in the passenger side kick panel. Below is it mocked up with the current setup.

Nice work!

Hawk03 wrote:I also found the horn relay which is not on the firewall. It is part of the harness in the interior and takes the three prong relay that is in the pic in the previous post. The wiring harnesses must have changed for the 76/77 years. I switched out the horns and it works although it only works when I take off the steering wheel cover and manually touch the button with metal. I think the button I installed in the column is too short to touch the metal plate. I have the sport steering wheel.

Wiring diagram.
https://imgur.com/a/QT5V0Lj

Yeah, looking at the bottom of page 4 in the diagram they note it as a 'junction block', so clearly it changed by 76. Can't speak to the steering wheel, but sounds right if it works when you short the wire manually. I don't think there's a 76 wiring diagram in the sticky for this section, so you should probably post that link there also in case someone needs it. However, if you're feeling ambitious, it might be better to save and repost each image instead in case that link ever stops working.

The pin/spring I bought was a one size fits all but I cut the pin too short. I'll have to buy a new one and cut it to the correct length. Story of my build, lol.

Credit for the wiring diagrams below. I did save each picture though.

https://www.g3gm.com/t296-wiring-schematics-needed

lars wrote:Hey guys,

I broke down and bought the $9 "Chevelle Wiring Diagram Manuals".

It's pretty great. Lot of things I've been wondering for years.

https://www.opgi.com/chevelle/1976/books/owners-manuals/WDM0076/

Figured I'd share.

https://imgur.com/a/QT5V0Lj

Not really sure how to attach them better without having to do every picture manually.

Hawk03 wrote:The pin/spring I bought was a one size fits all but I cut the pin too short. I'll have to buy a new one and cut it to the correct length. Story of my build, lol.

I think that's the story of everyone's build. I know I have accumulated a stockpile of parts that didn't work out as planned.

Installed the fuse panels. Now its time to start installing more stuff.  

Gentlemen, this is the best post on this site for the entire year. Kudos to you all.

REVINKEVIN wrote:Gentlemen, this is the best post on this site for the entire year. Kudos to you all.

I second that! This info, although overwhelming to the average car guy like me, was about as detailed and concise as any could be. Thanks for sharing your knowledge with us "beginners" lol.

Hawk03 wrote:Installed the fuse panels. Now its time to start installing more stuff.  

Nice work, Hawk! One last thing: document all of this. When you have to come back and make a modifications a year or two from now, you don't want to be scratching your head about what goes where.

g3chevy wrote:

REVINKEVIN wrote:Gentlemen, this is the best post on this site for the entire year. Kudos to you all.

I second that! This info, although overwhelming to the average car guy like me, was about as detailed and concise as any could be. Thanks for sharing your knowledge with us "beginners" lol.

Thanks -- I am always happy to help where possible, just like everyone else here.