Electrical current drop issue... - Pontiac GTO Forum
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post #1 of 26 (permalink) Old 04-12-2017, 04:41 PM Thread Starter
 
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Electrical current drop issue...

So my 1st cruise of the year ended with a tow home...The Fitech unit once again failed and would not all the car to start (mostly hard to start when warmed up).
I call Fitech and they stress to check the white wire which is my switched wire that is tied in with the ignition switch. I meter this while on the phone with tech and it shows about 12v exactly when switch is turned but drops as low as 1.5v when i roll the engine over. Tech advises me that i cannot have voltage drop here and this is the source of my issues.
Battery is older but meters out at 12.4v at rest.
The voltage regulator is new as well.

Suggestions? Bad ignition switch or voltage regulator or even battery? I'm a bit confused here...

Thanks!
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post #2 of 26 (permalink) Old 04-12-2017, 06:10 PM
 
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Temporarily, I'd run a known 12V sourced jumper wire, something with a toggle switch (on/off) to your white wire to eliminate your switch, voltage regulator, & battery. Turn the switch "on" to provide power as you fire your car up normally. If it runs well, and you do not see any voltage drop as you did with the current wiring, then I would begin to do some tracing. But me, if it worked with an on/off toggle switch, I'd keep it that way and maybe even hide it as a means to foil any would-be thief. Just sayin' as this is the best I can come up with not using anything but the old antique carburetor thingy on my cars.
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post #3 of 26 (permalink) Old 04-12-2017, 06:17 PM Thread Starter
 
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I did run a jumper wire from the battery to this white wire, essentially bypassing the switch. The car fired right up.
I guess my true question is: would this be a sign of a bad ignition switch? It just seems odd that the voltage drops so low when you crank the engine.
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post #4 of 26 (permalink) Old 04-12-2017, 06:59 PM
 
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Originally Posted by lil65gto View Post
I did run a jumper wire from the battery to this white wire, essentially bypassing the switch. The car fired right up.
I guess my true question is: would this be a sign of a bad ignition switch? It just seems odd that the voltage drops so low when you crank the engine.


Hmmm. Tough to say. I would think that some voltage drop would occur when you normally crank your engine. An ignition switch can go bad and I have had several go out on me, but they usually get finicky in that one time they start them they don't, then repeated tries gets it to fire, etc.. This is usually the tell tale sign its going.

Now there could easily be some resistance within the system somewhere due to age/corrosion of one of the wires. I found a wiring diagram here, if this is for your car: Pontiac wiring 1957-1965

Last edited by PontiacJim; 04-12-2017 at 07:51 PM.
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post #5 of 26 (permalink) Old 04-12-2017, 07:02 PM Thread Starter
 
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Thank you...lots to look at here i guess. Easiest thing would be to just find another switched source to splice into...lol
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post #6 of 26 (permalink) Old 04-12-2017, 07:20 PM
 
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I had a bad ignition switch do exactly that on my lemans. Changed the switch and back to normal. But I also wanted to get 12 volts to my distributor since I put in a Petronix instead of points. An easy way to do this is to take the white "ballast" run wire, and connect it to the 12 volt start wire, I spliced them with a crimp,solder,shrink butt connector.......

Then run a wire from that to the switch contact on a 12 volt relay. You then run a solid regulated 12 volt power source to the relay hot...and from the relay out to your coil.

You also add a small inline diode to the brown wire from the alternator that goes to dash battery warning light, to prevent run on.

This then works this way,...your start gives the relay switch 12, your run gives the relay 9 volts or so,...but the relay will close at about 5 volts and will stay closed with about 1.5 volts........but all the time will give full regulated power to your coil through the relay...and spark of course.

Now you have to fix the problem first, like a bad ignition switch if that is it. But using a relay will keep you running at full power, even if some contact or wire somehow somewhere creates a little resistance.

I use new wiring harnesses and soldered contacts etc, but I like the full 12 volts and or 14.2 etc that cool gets from full regulated power...

Starts every time...

Cost, a relay, a diode and a few connectors
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post #7 of 26 (permalink) Old 04-12-2017, 07:49 PM
 
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Originally Posted by lil65gto View Post
Thank you...lots to look at here i guess. Easiest thing would be to just find another switched source to splice into...lol
HMMM, just thinkin' again. You did not say which wire on the ignition switch you hooked to and I did not ask. LOL So let me try this again.

If you connect the white wire to the ignition switch "start" wire, the voltage will only show up when you turn your ignition key to the "start" position - it only sends current down the purple wire to activate the starter to fire up the engine. Once the engine fires up, you let the key snap back to the "run" position and the 12v running through the "start" position on the key shuts off (otherwise your starter would keep spinning when the engine was running).

One of the wires found in the plug that goes into the back of your ignition switch will be the "run" position/hot wire and should have 12V coming out of it. This should be the wire you want to tap into for continuous 12V power (which may be the red wire on the plug). Use your voltage tester to find the 12V (hot) power wire at the ignition switch plug. When you turn your key "on" this allows the 12V power to flow through your ignition system to both "start" and let the engine "run." When you turn your key "off" it cuts the 12V (hot wire) that keeps your engine running.

Now if that doesn't confuse you. So I am deleting my post on the "purple" wire as you need continuous power, not just at "start-up."
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post #8 of 26 (permalink) Old 04-12-2017, 08:01 PM
 
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Right PontiacJim,......the 12 volt start wire goes to distributor just for cranking,....once started the white cloth covered "Ballast" wire is the run wire which drops voltage to about 9 for running so points don't burn up.

If you have no points, you can run the full 12 volts in fact if you read the Petronix literature it actually recommends the full 12 volts.

The relay can go right on the firewall near the coil and the diode on the drivers side where brown wire is. No need to crawl under the dash to put on relay and diode.....

If you run points you must keep the ballast wire, or a ceramic ballast to drop run voltage.

I don't think one system is better than the other, in fact points gives a nice snappy throttle and start-up and won't usually leave you stranded. However I have had cheap imported "condensers" fail and the car won't run without changing the condenser. .....kinda like changing the module.

But if you have Petronix or HEI you can use full regulated voltage 12 to 15 volts as coils are rated like 8 to 19 volts, so it works good.

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post #9 of 26 (permalink) Old 04-12-2017, 08:04 PM
 
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Ps some starters have the "R" terminal some don't and there is the purple wire to starter etc...."

Just talking about power to coil...!
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post #10 of 26 (permalink) Old 04-12-2017, 08:08 PM
 
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Originally Posted by Lemans guy View Post
I had a bad ignition switch do exactly that on my lemans. Changed the switch and back to normal. But I also wanted to get 12 volts to my distributor since I put in a Petronix instead of points. An easy way to do this is to take the white "ballast" run wire, and connect it to the 12 volt start wire, I spliced them with a crimp,solder,shrink butt connector.......

Then run a wire from that to the switch contact on a 12 volt relay. You then run a solid regulated 12 volt power source to the relay hot...and from the relay out to your coil.

You also add a small inline diode to the brown wire from the alternator that goes to dash battery warning light, to prevent run on.

This then works this way,...your start gives the relay switch 12, your run gives the relay 9 volts or so,...but the relay will close at about 5 volts and will stay closed with about 1.5 volts........but all the time will give full regulated power to your coil through the relay...and spark of course.

Now you have to fix the problem first, like a bad ignition switch if that is it. But using a relay will keep you running at full power, even if some contact or wire somehow somewhere creates a little resistance.

I use new wiring harnesses and soldered contacts etc, but I like the full 12 volts and or 14.2 etc that cool gets from full regulated power...

Starts every time...

Cost, a relay, a diode and a few connectors


Ah, sounds too much like rocket science to me. Sounds like a good solution, but, I think a pencil drawing, however crude, might really help here (at least me, anyway). I am trying to picture this myself in how you got it set-up, but my feeble mind is struggling to imagine how this all goes together - "This then works this way,...your start gives the relay switch 12, your run gives the relay 9 volts or so,...but the relay will close at about 5 volts and will stay closed with about 1.5 volts........but all the time will give full regulated power to your coil through the relay...and spark of course." 12, 9, 5, & 1.5 volts?????


Will this work on most year cars?
Will this only work for HEI or electronic ignitions/conversions?
Maybe some pictures too of your relays/connections?
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