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Discussion Starter #1
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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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. :thumbsup:
 

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Discussion Starter #3
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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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
 

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Discussion Starter #5
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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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...:nerd:

Cost, a relay, a diode and a few connectors:nerd:
 

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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
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." :blush:
 

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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.

:nerd::nerd:
 

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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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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...:nerd:

Cost, a relay, a diode and a few connectors:nerd:


Ah, sounds too much like rocket science to me. :yesnod: 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????? :confused:


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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You are right PJ it does sound like a mess....!

So let me see if I can make it better, can't get a diagram at the moment....

So the wiring harness has 3 wires that come out....a purple wire to starter solenoid......and two others to coil one is a cloth covered ballast wire

For run, about 9 volts,...the other forget the color but is the full 12 volt start wire.....

So when you crank all the way over the full 12 go to coil...when you let go to run 9V ballast wire takes over So points don't burn up.

So if you don't need the 9volts and want 12+ al the time, you take those two wires off the coil + and strip and twist the ends together....

Right behind the coil on firewall mount a relay, which has 4 wires....a ground to a screw in firewall,...one a switch that activates the relay...

And 2 others that are full power in and out...the high power you are using the relay for....

Take the 2 twisted wires and with a female connector attach to "Switch" wire of relay. That activates relay.

Then from a regulated 12v source ......connect a wire to one side of the relay,...and the other side of relay to coil....

Now when you turn the key, the 12 volts from the start wires closes the relay.....the powered relay goes direct to coil full regulated power...

When you release the key, the 9 volt ballast wire takes over to the relay switch..still way more than enough to close the relay......

If the relay is closed then full power goes to coil, it does not matter that 9volts holds it closed or even 2 volts, if it is closed full power to coil.

So it is more power and very forgiving.....you must splice in a diode in brown alt wire, real easy.....

Sorry I can't draw you something right now, but is basically splicing a 12 volt relay, ...(make sure you use a relay that has no internal ballast drop.....).....between the coil and ignition switch but at the firewall where it is much easier to do....

Don't mean for it to sound convoluted, my apologies:nerd:
 

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Yes it will work on HEI Petronix, but cars originally HEI won't need it as they did not have a drop to 9 volts.

Some cars have a ceramic ballast on the firewall, corvettes, and you can connect there and just eliminate the ballast, or you can trace the ballast wire to the firewall and eliminate it there and connect it to the 12 volt source there, or do some work under the dash splicing at the ignition switch, or run

wire that has no ballast drop.....

But the relay is real easy to do, does the same and better as any resistance in that switch wire that develops, from wire contacts vibration would have to get awful low for that relay not to give a full 12 to 15 volts...

As 8 said the relay switch will close at about 5 or 6 volts and it only takes 1.5 volts to keep it closed....

It is an easy install if you don't like pulling out the connectors at firewall and under dash stuff.....Petronix even recommends it, if you don't want to do all that other stuff.
 

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Discussion Starter #13
PJ, I don't recall the color that I spliced into with that switch but it supplies power when turned "on" or "acc" and during "crank" (I will look tonight when I get home).

LG, I have a Petronix unit installed in my original points-style distributor

This is a 1967 Lemans that originally had an OHC6 (now a 400) in it. I don't recall seeing any ceramic ballasts anywhere.

Thanks again...I will jump into it tonight and see what kind of damage I can do! :)
 

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so PJ asked for some photos....here is the relay on my firewall.....

the blue wire is what switches on the relay. it is attached to the white cloth covered ballast wire and the run wire which is black with white stripe....

they both originally had been hooked to coil positive....now switch on relay

the green is just ground for relay to a screw..... the red wire goes to "regulated power"...

the yellow wire then goes to coil Poitive. a diode is in the brown wire from alt that goes to dash light, it is in my harness where the white line appears above the bus bar.

I use the MAD Electrical system plan, Mark Hamilton at MAD is a genius on this stuff...but if you don't have that normally regulated power is available at the Horn Relay positive terminal....

so a car that was originally points can go to full 12v to coil easy this way and go back to points easy be taking out the relay and diode and untwisting the two wires, Ballast and run and hooking them back to coil

if you run an MSD box you don't need it as the MSD box internals basically do the same thing and provide full power out on their big wire...

and the switch wire in does not need much,...same as a relay really for that effect..

cars originally HEI don't need it....but if drop an HEI or Petronix in a original points car this is a little better than letting run on 9v, they still work but the margin for just a little resistance is slight.

so I hope that helps, just a standard 12v 30 amp relay with no internal resistor
 

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Discussion Starter #16
Lemans Guy,
Can I do this, for simplistic reasons (I will never be an electrical engineer):

1) Acquire a relay
2) Run a wire directly from the battery, to a leg on the relay
3) Run my current switched power from the ignition switch to the relay (This is the one where I'm getting low voltage on 'Cranking')
4) Finally, tie my white wire (running my fuel pump) to the relay.
This would give me my solid 12v power that I need, correct?

I've read this elsewhere and cannot believe it would be this easy?
 

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Lil65.....No not exactly,....you must tie power to the relay to "Regulated Power", not straight battery power.
The reason is the coil has to operate with That when the car is going. The "voltage regulator"is either external or inside your alternator grabbing that power is what you want for any thing like a coil.

You have to first find and fix that voltage drop,..then make changes, but if you are running an elder
Trick fuel pump you may want to call Mark Hamilton at MAD Electronics,....just google it and get his kits. They take care of all that stuff, and make the system very reliable and powerful.mfrom strong headlights to reliable start-up. If you are not going for total originality, and want real bright lights and full power to all systems his full power kits are really great.

You are paying for his knowledge but his wiring is superior stuff he has special made even the wire cover is thick with high heat resistance..

Just Google him and call him,....tell him a guy in Tennessee told you to call!
 

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OK, turned these around for a better view.

lil65gto - "I have a Petronix unit installed in my original points-style distributor"

PJ - I assume you are not using the factory resistor wire and have run a jumper wire? You need 12 volts when using this conversion.

If you are still using the factory wiring, you get 12volts when you hit the "start" and then your points will run on the resistor wire when you snap the ignition back to the "Run" position. The resistor wire gives lower voltage so the original points do not burn out. Lemans Guy's set-up will take care of this and give you the 12V you need if you don't already have it.

Just checkin' :thumbsup:
 

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Discussion Starter #19
PJ, no...I did not remove any resistor wire. It is my understanding the original Petronix did not require this (Petronix 2 did?).
I pitched using a simpler Lemans Guy resistor idea to do a quick elimination of my voltage issue at hand, with the voltage drop with the fuel pump. I gotta say...electronics or electrical isn't my thing. I can do most ANYTHING but I'll send the car down the road if I have to keep messing with electrical... :)
 

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"PJ, no...I did not remove any resistor wire. It is my understanding the original Petronix did not require this (Petronix 2 did?)."

OK, not sure. I used a 12 volt jumper wire on mine (the first version of the Petronix conversion). But, I found this on one of the threads, "Feb, 2006 - Called Pertronix today, was told that their coil (Flame Thrower) needs 12volts to work properly so no resistance wire. If it's an OEM coil use the resistance wire and if you are using an later model coil it probably will need the full 12 volts."

I used a hotter coil than stock. It may be worth an email/call to confirm this. Don't know if you still have any directions? There is a PDF online that shows ways to hook the distributor up along with the resistor wire in place by using a jumper wire, but don't know what version this applies to although this looks like the original conversion: http://www.pertronix.com/docs/instruction-sheets/1141.pdf
 
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