Ignition on 12V and on crank 12V

[Finlay Macpherson]

Hi all, im struggling to find an on crank 12V ign on 12 V supply on my 79, ive tried the in cab loom that comes from steering column but nothing seems to supply 12V while on crank, ive tried the 2 red, 2 orange, pink and brown with no luck

can anyone point me in right direction, its needed for my holley Term X

manythanks

finlay

 

[Matt69olds]

Pink should have power in crank and run. If not you most likely have a ignition switch problem.

Red is power from the battery, and will have power all the time, brown in run and accessory, purple in crank, orange supplies power to fuses that are powered at all time also.

 

[Finlay Macpherson]

Pink should have power in crank and run. If not you most likely have a ignition switch problem.

Red is power from the battery, and will have power all the time, brown in run and accessory, purple in crank, orange supplies power to fuses that are powered at all time also.

Perfect, cheers

 

[AuroraGirl]

Pink should have power in crank and run. If not you most likely have a ignition switch problem.

Red is power from the battery, and will have power all the time, brown in run and accessory, purple in crank, orange supplies power to fuses that are powered at all time also.

would that be best for an electric choke?. pink that is

 

[broketiredugly]

most electric chokes ran off alternator output.

 

[AuroraGirl]

most electric chokes ran off alternator output.

That doesnt seem... logical to me. I heard that cycling the power to an electric choke when putting an edelbrock for example can confuse it or something. Like, it powers on and off with the key. On alternator it would change everytime the belt moves,so key cranked. But it wouldnt adjust when truck is off?

 

[broketiredugly]

run off alternator to keep battery from discharging or choke spring getting weak if key left on. thermal spring engages choke, 12v heats spring, relaxes spring, slowly opens choke.

 

[AuroraGirl]

run off alternator to keep battery from discharging or choke spring getting weak if key left on. thermal spring engages choke, 12v heats spring, relaxes spring, slowly opens choke.

So the choke does NOT need power at cold startup? Or...im not sure. I guess im intrigued, you have my attention. Im ready to learn

 

[Matt69olds]

Try this

http://www.gmcmhphotos.com/photos/e...60-electric-fuel-pump-and-electric-choke.html

using the oil pressure safety switch will keep the choke from heating up unless th engine is running. If your running an electric fuel pump, you should already be running one of these switches anyway.

 

[AuroraGirl]

Ive been using switched ignititon off the wipers. So maybe im making my truck harder to start because the choke opens up when im turned off? But I guess i ask because its a lot easier to tap off the alternator than that switch, yes? I believe that switch resides near the pan? And what does that switch function? My engine originally ran a thermostatic choke, only off intake manifold. no electrical.

 

[MikeB]

I would not use the pink ignition wire to power the choke, unless it was 10 gauge. Even then, I'd do it only if there wasn't a dedicated choke circuit or another circuit that could handle as much as 25 amps, which is what an HEI can draw on start-up!

I don't understand how or why an alternator wire would be used to power the choke. I assume this is the exciter wire? What is that, 16 gauge?

As mentioned above, the factory ran the choke wire through an oil pressure switch. That way the choke won't open while you're trying to start the engine -- for example, having to crank it a long time on a very cold day or if the truck hasn't been started for weeks.

Yes, 12v on the choke heats a coiled bi-metal strip that opens the butterfly.