Ignition Unfused posts always hot
 

after finally getting this 72 C 10 Cheyenne to run after installing new fuel tank vape lines, fuel lines and a brand new speed Demon Holley Carb truck fired up first shot but we can not turn it off. After adjusting idle advances still no luck. I am no mechanic. And the old quadrant which was leaking like a sieve would diesel a bit when you shut it off but it would at least shut off.

I was checking fuses and terminals at fuse block & upon testing Ignition Unfused terminals realized they are always hot! Battery has been draining and I thought it was because horn button did not have a spring so horn would randomly go off so I just disconnected the horn but I realize that if horn contact is still engage it would drain battery. I've since fixed the horn but can't figure out why the truck won't turn off and why ignition Unfused terminals are constant hot.

I even unplugged the ignition switch thinking that might cut power to ignition Unfused terminals but it did not. Any ideas?

BtW truck has HEI dist

1972 C10 Cheyenne w 402 and 4 on the floor

Re: Ignition Unfused posts always hot
 

I wonder if you have a short somewhere, or a cross in a circuit where your lighter or dome lamps or something always hot is spliced into the IGN circuit?

I would have guessed the switch too, but if it's disconnected, not that...

You could try popping fuses out of other circuits and see if that removes power to the IGN lug, at which point you'd know what circuit is crossed (if one is).

Hmmmm sounds like a good idea to try that, I had not thought of it.
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Re: Ignition Unfused posts always hot
 

Check starter solonoid--tach--alternator diod--just my 2 cents--hope this helps--happy trails

Re: Ignition Unfused posts always hot
 

Dave PL, thanks for the help removed all the fuses but no luck Ign un fussed still hot. I did test the leads at the switch harness and both "BAT and IGN wires are hot.

The switch has 2 extra posts that the harness does not have wires in so im gonna have investigate if there is supposed to be wires there it looks like the switch has 2 bat terminals but only 1 has a wire going to it from the harness and the G1 stud also does not have a wire going to it.

The wiring in this thing was all a tangled mess with a few leads not connected at all, Im sorting that all out and try to reconnect everything where it goes.

Re: Ignition Unfused posts always hot
 

Paul B thanks for the response, Theres a Diode on the Tach? Sorry im not super electronically proficient, I can do home electrical but 12 volt I need to learn more. LOL.

I did check voltage at alternator there are obviously 12 volts that come from the splice that feeds alt, voltage regulator and a few other items. How would I test to see if the Diode at Alt is working. Is my understanding correct that the diode allows power to only go one way and not feed back?

Re: Ignition Unfused posts always hot
 

Cesar-going back to engine wont shut off ! If some one has used jumper cables and connected them wrong the alternator diode would most likely open and let electricity to bleed back through the negative side of charging system causing battery drain and possibly keeping engine running with switch off! With engine running you should have 13 to 14.2 volts or so. Sounds like you might have more problems from wiring. I would make sure battery is fully charged, run engine with alternator disconnected and see if engine shuts off!! You might be chasing more than one problem. At least you will know the charging system is ok!

Re: Ignition Unfused posts always hot
 

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Do you know how many wires are connected to the starter solenoid and what color they are?

LockDoc

I do not I think there's three I will have to check. Today after cleaning up and zip tying wires and reinstalling seats and gauge cluster, now truck will only turnover will not start. Also noticed that Battery Terminal at cool is constantly hotnehichni assume that it would burn out the HEI coil.
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Re: Ignition Unfused posts always hot
 

Sorry, I'm not understanding your last sentence above.

LockDoc

Battery wire to coil is also hot instead of switched with ignition which I assume would burnout the coil if it's constantly hot
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Re: Ignition Unfused posts always hot
 

I don't know if it would burn out the coil but that would be the reason the engine wouldn't shut off with the key....

Without being there it is really hard for me to diagnose this type of problem but it is obviously in the wiring. Was the instrument cluster changed from idiot lights to gauges by any chance? The wiring has to be changed on the cluster connector if that is done.

Has the ignition switch been changed out? There are two different ignition switches: '67 & early '68 (no accessory position) and late '68-'72 with an accessory position. The wiring is also different between the two.

LockDoc


LockDoc

We got the truck from an indian reservation in Nee Mexico it's 90% original switch looks to be original. I noticed pigtail to ignition switch has less wires the. # of pins on switch. We did remove clean and attach a new gauge bezel but gauges are original. Everything but Tach and oil pressure works. There's an alternate oil pressure gauge. I removed switch and there is still power to ign unfused and to coil. I will check starter wired we did Install a new battery cable maybe we wired it to the wrong post on starter. Also noticed a pigtail on HEI dust that is not connected to anything.
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Re: Ignition Unfused posts always hot
 

OK so I realized that the pigtail from distributor had come undone from the coil so that problem is solved, the truck now starts. I glanced up at the starter solenoid and there are 2 leads to the battery terminal and another to the S terminal it does not appear to have a wire on the I terminal. We took it for a drive and it was too cool, first time! Had to stall it to shut it down.

Are there supposed to be two wires to battery terminal on Starter solenoid?

Re: Ignition Unfused posts always hot
 

Maybe someone hotwired the vehicle in the past (and if so you might want to verify that he vehicle wasn't stolen at some point!).

If you have HEI there shouldn't be any connection from the starter to the distributor.

Re: Ignition Unfused posts always hot
 

Cesar-did you check the alternator--disconnect alternator and see if it engine shuts down!!!

Re: Ignition Unfused posts always hot
 

Battery cable should be the only thing on the battery terminal. Can you tell where the other wire goes? Purple wire should be on the S terminal and The I terminal isn't used with the HEI.

LockDoc

Well after noticing a second wire on the battery terminal it was back feeding directly to the switches terminal so it was a constant feed to distributor, and ignition unfused posts and a few other doses terminals.

Thank you all for your help this sight is awesome. Truck now turns off, apparently they were stalling the truck to shut it off. Appreciate everyone's help.
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Re: Ignition Unfused posts always hot
 

Glad you got it sorted out...:)

LockDoc

Thank you so much for your help, it was invaluable.
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