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Need a key on 12V source:

vandelay industries

vandelay industries

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It's getting colder and i think i've run out of slots on the fuse panel for a 12V source for the choke; i cannot yet run this off of the 2-prong plug near the oil filter because 4.3's are actually a little different in that area (the sensor is too short whereas on a v-8 it would work) and i don't have time to mess with that right now.


Where else besides the fuse box can i get a key on only 12V source?

Or, if there is a way to add circuits/fuses to the fusebox, how would you do that?
 
IIRC, GMs use a 12V normally ON with ignition to the wiper motor which you can tap as below:

Find the ON excited wire and add a relay into it in by tee-tap and use the relay with a fuse on the power supply to bring the 12 volts to your project.

Nothing wrong with in-line fuses as long as you remember where they are and they are accessible. Why overload an existing fuse panel when this is so much easier?

Sorry for no pictures of the system I use. Here's a link for you: http://www.rbracing-rsr.com/turbo/wiring_pix/spdt_relay02.jpg.
 
Not a big fan of tapping into anything, that's my personal preference.

What year are you dealing with? I'm pretty sure both blade fuses and glass can be purchased with a "pigtail" off of them. Probably about the easiest, cleanest solution if you've already run out of slots.

Note that if blade fuses, the accessory terminals can be "piggybacked" with factory connectors, in some applications GM used connectors that had a slot on the back side, that you could plug yet another connector into.

If you have any expectation of running more accessories, look into an auxiliary fuse panel like late model vehicles used under hood. They have relays and fuses, you use one relay to turn on an entire row of circuits. Much cleaner and and easier if done underhood, as you don't have to run any heavy wires very far from the battery.
 
All the same, a factory fuse box, wherever it's put is usually loaded to 80 or 90% of its capacity by corporate bean counter design.

If you're going to add anything to it, you've got to find a separate 12v, constantly ON supply and an IGNITION ON signal that might be found in a spare tap in the fuse panel to fire the relay.

Never piggyback a fuse. Danger Will Robbins!

The reason for the relay is to keep this newest addition to the OED working load totally away from the fuse panel itself.

Of course an in-line fuse holder is required....ATCs are usually best, but I've seem MAXIs used intelligently and neatly too. Glass tubes are one of the singularly most troublesome fuse denominations of safety devices ever made IMO, especially as an add-on device. The holders are problematic to say the least.

BTW: a TEE tap, not a Scotch-Lok - is not what I referenced, as a Tee tap is a soldered connex. Scotch -Loks are a joke.... temporary at best and as an emergency, zombie attack field repair - is a: maybe.

Anyway - a safe and decent source for constant 12v is the twin stud isolator junction on the firewall, below the cowl, usually on the driver's side under the hood.

The OP didn't say his was a Concours d'Elégance Restoration anyway.
 
GM truck fuse boxes of the 80's generally had vast swaths of unused terminal positions. A K5 in Silverado trim used the same fuse box as a custom deluxe 2WD pickup with manual everything. As time went on, and "luxury" became more of a selling feature, those extra spots were used pretty extensively.

I (apparently) mistakenly assumed this vehicle was going to be sold at Barrett-Jackson, thus my recommendations to get the maximum value at auction.
 
I've used an Add-a-Fuse before with good results, although if you use a bunch of them it can look sloppy and hinder access to other fuses. Tapping an unused terminal in the fuse box is definitely the neatest solution, although the most work.
 
paratrooper307 said:
I've used an Add-a-Fuse before with good results, although if you use a bunch of them it can look sloppy and hinder access to other fuses. Tapping an unused terminal in the fuse box is definitely the neatest solution, although the most work.
Click to expand...

I can understand the reason for not advocating for this option. Even though you are fusing it, the wiring leading to the fuse itself from the power source is potentially not rated for more load, which is what fuse taps allow you to do.

Most of the fuse panel is fed off ganged terminals anyway, so to accurately say it's ok (or not) to run fuse taps you'd need to know the wire gauge leading up to the fuse terminal, plus any switches or connectors used up to that point, to ensure you aren't exceeding the capacity of any of them. It is entirely possible that a block of fuse terminals is being fed by wiring with 20A capacity, but only has one circuit connected drawing 5A, and it's also entirely possible there might be an 18A draw on the circuit to start with.
 
It's and 83 that originally had a 305, but i've swapped in a 4.3. And ,no, it's not a Barett-Jackson restoration.

i have seen those piggyback fuse things, but i've read those aren't really recommended. (even though i don't think the choke really uses that many amps?)

i'm thinking the circuit on the fuse box labelled "choke" is probably where i need to be looking at? Somehow just bypass the sensor and run it directly to the choke?
 
I've only had one problem with the spade type add on fuse holders in many years. The glass type were most always a disaster. If they got hot - which they did regularly - then they'd weld themselves to the holder and they wouldn't come out without breaking the glass tube.

But that's just me I guess.

I still don't like tapping into an existing fuse box... and that's just me too I guess.

Most add-on accessories I put on are really big power suckers that draw 50 or 60 amps and I hate the smoke when it comes out of the OE fuse panel.

Then again, I'm not looking for The Smithsonian Institute to call me asking for my K5 as an exhibit either.
 
vandelay industries said:
It's and 83 that originally had a 305, but i've swapped in a 4.3. And ,no, it's not a Barett-Jackson restoration.

i have seen those piggyback fuse things, but i've read those aren't really recommended. (even though i don't think the choke really uses that many amps?)

i'm thinking the circuit on the fuse box labelled "choke" is probably where i need to be looking at? Somehow just bypass the sensor and run it directly to the choke?
Click to expand...


Your truck should have a wire and fuse provision for the electric choke already,in the fuse box there should be one fuse spot labeled for the choke--there should also be a wire for an idle stop solenoid too,which you could also use to power the choke..

The carbed trucks of that era had a "choke" indicator lamp on the dash,and if the choke lost power or the heating element failed,the lamp would light up to warn you,that soon it will possibly flood out and stall..or at least run very rich and dilute the oil.
 
This is what I'm talking about:



I don't think there is a problem if GM did it from the factory. You can see that the pink connector with the orange/black wire (and the black connector, and both clear connectors with pink/black wires) has another position on the back of it. That gave GM the ability to run another component off of there. Those circuits on the later fuse panels are off of a 30A breaker, no idea about the ones as pictured.

But, it gets ridiculous as you add more and more circuits, it really becomes a mess. Not to mention, you still have to fuse anything you add to it separately, since the breaker is for everything off that panel position. This is KIND of what I'm talking about, but there are smaller ones that can be found. Either just fuses, and you add relays that are switched based on whatever inputs you have (ignition, headlights, etc) or get one that has relays integrated in it.
441.jpg
 
You can see the "choke" fuse in the upper left corner...GM thought it was OK to get power there for it,that is where I'd put a wire,if the truck lacks one,but it should have a factory wire in the harness already..
 
diesel4me said:
You can see the "choke" fuse in the upper left corner...GM thought it was OK to get power there for it,that is where I'd put a wire,if the truck lacks one,but it should have a factory wire in the harness already..
Click to expand...

I forgot to address the oil pressure switch. The reason the choke is on a switch is so that the choke coil isn't powered when the engine isn't running, but the key is not in the "off" position.

Not likely an issue, but something to consider.
 
Yeah,I thought about that--but I wasn't sure if it was the choke or an electric fuel pump the oil pressure switch controlled--guess an 83 wouldn't have an electric pump ,only '87 and up would..
 
I meant factory installed electric pump--until '87 when GM went with fuel injection they only used mechanical fuel pumps--of course you could add an electric one yourself..
 
diesel4me said:
Your truck should have a wire and fuse provision for the electric choke already,in the fuse box there should be one fuse spot labeled for the choke--there should also be a wire for an idle stop solenoid too,which you could also use to power the choke..

The carbed trucks of that era had a "choke" indicator lamp on the dash,and if the choke lost power or the heating element failed,the lamp would light up to warn you,that soon it will possibly flood out and stall..or at least run very rich and dilute the oil.
Click to expand...

i think i am just going to jumper the 2 prong plug that would normally go over the 2 prong oil sensor (Long story why i can't use the sensor right now). But the idle stop solenoid power wire is an idea. And yes, i have and idle stop solenoid. i am not using it now because i removed the A/C mainly to clean up the engine compartment. What would this ISS wire be labeled under on the fuse box?
 
Using the ISS circuit - really? Is it still powered up as an ISS? And do you think it's ON all the time?

One more time (because I'm old and don't remember and I'm too tired to scroll back and read if it's there in the OP or not) what year/make/model vehicle is this?

Any system with an ISS is somewhere (help me here, why not?) in the late '60s/mid '70s or so - maybe up to '85 - right?

Find out if the ISS is still powered under the emission control system before you start wiring it up as a KOEO power supply. .

This simple project is getting 'way out of control. Gaa-ack!

If there's ANY computer left to operate this system - don't go poking wires with a test light to find 12.0 VDC or you might find 5.0 VDC and smoke something computer-wise with your non-Hi-Z test light. .
 
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