Ignition switch mystery

[Neal Zimmerman]

Here's something I cant seem to find any info on,
On our ignition switches we have a largeish Blue and brown wire. These are start1 and start2, or START and RUN. Brown wire is for start (key far to the right0 and blue is for run (key first click to right). These two wires have to do with the ballast resistor.
I was messing around and put the key to run position and put my test light on the blue wire and it lit up. Seems right. Then I decided to test the brown wire. Cranked key all the way to the right, and brown wire lit up. Seems right.
But then I put key back to run position and checked the blue wire, still good. But then I put test light to the brown wire ( key still in run position) and it also lit up, but at about half the brightness of the blue wire. Is that correct? I thought it would be a no light up reaction. But apparently some current is still travelling thru
there. ?
Is this normal or is my switch bad? And if its good can somebody explain this.
thanks
Neal

 

[RemCharger]

The 2 wires are both on the ignition circuit. So you are seeing a backfeed from the ballast resistor .
Normal.

 

[snakeoil24]

What your seeing like above or more likely the9.2 volt expected after ballast resistor.

Start circuit drops out when you switch to run and then start wire should have dropped off.

 

[wagonman]

Ok let me see if I can explain. Both supply 12 to the ballast Brown in crank Blue in run. The blue should also split to power the Voltage regulator. On the other side of the ballast is the step down voltage from the blue and the full voltage from Brown. Pull the brown off and you should have Voltage only in the crank position. What you are seeing on the brown is the 9 volts that will go back to the ignition sw but not through the Sw contacts. Get It? Test lights are a good tool but a volt meter is better even one of the free HoBo freight one. Test lites only pull a small amp load and do not load the circuit very much like to check for a poor connection at the Bulk Head Ect. I rigged up a Halogen headlite bulb as a tester it draws 4 amps IIRC and will really load the Ckt. Caution they get Hot and will burn you. Run it through an old Mc Donalds coffee cup for protection.

 

[Neal Zimmerman]

OK, I kind of get it. Sounds like the switch is okay.

 

[snakeoil24]

Ok let me see if I can explain. Both supply 12 to the ballast Brown in crank Blue in run. The blue should also split to power the Voltage regulator. On the other side of the ballast is the step down voltage from the blue and the full voltage from Brown. Pull the brown off and you should have Voltage only in the crank position. What you are seeing on the brown is the 9 volts that will go back to the ignition sw but not through the Sw contacts. Get It? Test lights are a good tool but a volt meter is better even one of the free HoBo freight one. Test lites only pull a small amp load and do not load the circuit very much like to check for a poor connection at the Bulk Head Ect. I rigged up a Halogen headlite bulb as a tester it draws 4 amps IIRC and will really load the Ckt. Caution they get Hot and will burn you. Run it through an old Mc Donalds coffee cup for protection.

The one item to explain is voltage drops on both start and run with regulator being fired by 12.6 plus.

 

[wagonman]

The one item to explain is voltage drops on both start and run with regulator being fired by 12.6 plus.

Well it seems Neil dosent have a DVOM and I dont want to confuse Him. Easy enough to search and applys to all rigs.

 

[Neal Zimmerman]

Whats a DVOM?

 

[kiwigtx]

Whats a DVOM?

Digital Voltage Ohm Meter. .....at a guess. I have never used that term myself....more commonly called a Multimeter.

 

[mikeymopar]

@wagonman is the man with his explanation. Granted this is an image for electronic ignition, but it all relates. You get more voltage to "Start" cos it's direct to the coil bypassing the ballast resistor and lower more manageable voltage to "Run" thru the ballast resistor. Easy pic to follow the voltage.

 

[Nacho-RT74]

becarefull with that diagram... it shows the secon ign feed coming from starter relay which is true on lates 70s, but certainly not up to 74 at least what it comes from ign switch really.

The ballast becomes on a splicing power source or junction to both Ign circuits. The Ign 1 and Ign 2 circuits reachs one side of the ballast each one. depening on which Ign circuit is being activated, while in run or cranking, the other side will be retrofeeded with the logical ballast influence and power decay.

So when in RUN, Ign 1 circuit it gets full 12 volts while Ign 2 remains hot with a power decay ( anything between 4.5 up to maybe 10 volts ). This includes the wire to the coil of course.

While starting, the Ign switch will change to feed Ign 2 circuit which reachs straight to the coil bypassing the ballast, but the Ign 1 circuit will remain hot, with the consecuent power decay of course running trought the ballast

This is the reason why the brake and oil lights ( if equipped ) will dimm out while cranking, because this lights are hooked up to the RUN circuit ( Ign 1 )

This happens just while ballast is conected and in working order.

 

[Neal Zimmerman]

OK, it's making more sense, Thanks Nacho

 

[mikeymopar]

Ah, yes. Should've specified it was a generic, most simplistic diagram. Obviously gonna be a little different thru the years. But you get the general idea why the voltage drop would be present due to the ballast resistor. My '77 Charger, when traced out, was physically different but similar electrically to the pic but my '68 Charger is nearly identical.