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#1 |
Registered User
Join Date: Jun 2016
Location: Stevenson Ranch, CA
Posts: 62
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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 |
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#2 |
Registered User
Join Date: Aug 2006
Location: Redmond, WA
Posts: 6,332
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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).
__________________
1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible |
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#3 | |
Registered User
Join Date: Jun 2016
Location: Stevenson Ranch, CA
Posts: 62
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Quote:
Hmmmm sounds like a good idea to try that, I had not thought of it. Posted via Mobile Device |
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#4 |
Senior Member
![]() Join Date: Jan 2016
Location: massachusetts
Posts: 328
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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
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#5 |
Registered User
Join Date: Jun 2016
Location: Stevenson Ranch, CA
Posts: 62
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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. |
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#6 |
Registered User
Join Date: Jun 2016
Location: Stevenson Ranch, CA
Posts: 62
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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? |
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#7 |
Senior Member
![]() Join Date: Jan 2016
Location: massachusetts
Posts: 328
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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!
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#8 |
The Older Generation
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Location: Montezuma, Iowa
Posts: 25,486
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Re: Ignition Unfused posts always hot
-
Do you know how many wires are connected to the starter solenoid and what color they are? LockDoc
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Leon Locksmith, Specializing In Antique Trucks, Automobiles, & Motorcycles (My Dually Pickup Project Thread) http://67-72chevytrucks.com/vboard/s...d.php?t=829820 - |
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#9 | |
Registered User
Join Date: Jun 2016
Location: Stevenson Ranch, CA
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Posted via Mobile Device |
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#10 | |
The Older Generation
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Location: Montezuma, Iowa
Posts: 25,486
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Re: Ignition Unfused posts always hot
Quote:
Sorry, I'm not understanding your last sentence above. LockDoc
__________________
Leon Locksmith, Specializing In Antique Trucks, Automobiles, & Motorcycles (My Dually Pickup Project Thread) http://67-72chevytrucks.com/vboard/s...d.php?t=829820 - |
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#11 |
Registered User
Join Date: Jun 2016
Location: Stevenson Ranch, CA
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#12 | |
The Older Generation
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Location: Montezuma, Iowa
Posts: 25,486
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Re: Ignition Unfused posts always hot
Quote:
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
__________________
Leon Locksmith, Specializing In Antique Trucks, Automobiles, & Motorcycles (My Dually Pickup Project Thread) http://67-72chevytrucks.com/vboard/s...d.php?t=829820 - |
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#13 | |
Registered User
Join Date: Jun 2016
Location: Stevenson Ranch, CA
Posts: 62
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Quote:
Posted via Mobile Device Last edited by Cesar Diaz; 08-02-2016 at 02:59 PM. |
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#14 |
Registered User
Join Date: Jun 2016
Location: Stevenson Ranch, CA
Posts: 62
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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? |
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#15 |
Registered User
Join Date: Aug 2006
Location: Redmond, WA
Posts: 6,332
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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.
__________________
1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible |
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#16 |
Senior Member
![]() Join Date: Jan 2016
Location: massachusetts
Posts: 328
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Re: Ignition Unfused posts always hot
Cesar-did you check the alternator--disconnect alternator and see if it engine shuts down!!!
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#17 | |
The Older Generation
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Location: Montezuma, Iowa
Posts: 25,486
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Re: Ignition Unfused posts always hot
Quote:
LockDoc
__________________
Leon Locksmith, Specializing In Antique Trucks, Automobiles, & Motorcycles (My Dually Pickup Project Thread) http://67-72chevytrucks.com/vboard/s...d.php?t=829820 - |
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#18 | |
Registered User
Join Date: Jun 2016
Location: Stevenson Ranch, CA
Posts: 62
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Quote:
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. Posted via Mobile Device |
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#19 | |
The Older Generation
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Location: Montezuma, Iowa
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Re: Ignition Unfused posts always hot
Quote:
Glad you got it sorted out... ![]() LockDoc
__________________
Leon Locksmith, Specializing In Antique Trucks, Automobiles, & Motorcycles (My Dually Pickup Project Thread) http://67-72chevytrucks.com/vboard/s...d.php?t=829820 - |
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#20 |
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Join Date: Jun 2016
Location: Stevenson Ranch, CA
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1972 c/10, electrical issues |
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