Time For a New Ignition Switch?

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Nelson7604

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I broke in my 318 a couple days ago. After I took the heads off to replace the inner springs and got it all back together, I have no ignition. I converted the points ignition to electronic and I checked all of the wiring and everything checks out OK.

The key will let me crank the starter but won't give me ignition.
But here's the kicker: It tries to fire momentarily when I put the key back into "run" position and the ballast resistor gets hot, not warm.
Is it time for a new ignition switch or is there another problem?

1972 Dart 318(originally 225)
Thanks
 
If it cranks and runs while the key is in the start position then immediately dies when you release the key to the run position, the ballast resistor is bad.
 
Could be either the switch or the ballast, as the switch has two positions that it puts power out to the ignition circuit.
In the wire diagrams you will see Ign1 and Ign2 and either one can go out in the ignition switch. Either side can go out on the ballast also.

If you have a 4 pin ballast resistor both top and bottom connector should have power to them (one in start, and the other in Run) Tested at the main harness side.

Test for this with a test light at the two harness side ballast connections and you will probably find that the ballast has power to it in one wire in Start, and the other in Run.

If this is indeed the case then the switch is fine and the ballast resistor died.
 
Hi,

When you say you converted from points to electronic ignition, which electronic system did you use? Is it a Chrysler type system?

Some of the previous posts are talking about a Chrysler type system and you may be using something else.
 
Pete in NH said:
Hi,

When you say you converted from points to electronic ignition, which electronic system did you use? Is it a Chrysler type system?

Some of the previous posts are talking about a Chrysler type system and you may be using something else.
Click to expand...

Good point.
 
Sometimes it fires once after I move the key to run position, but it doesn't run which makes me think it is the ignition switch.

I am using a mopar electronic ignition control unit with appropriate wiring harness.
I checked voltage between coil(+) and ground with key in "run" position and i have 5.95v.
Resistor has 1.5ohms(two pin resistor)
Might be too much?
I checked the coil and I have the appropriate resistance with primary and secondary coils.
I checked the wires to and from the resistor in run and in start positions and it does what it is supposed to do(12v in run and 0v in start and vice versa)
I also checked for spark using the screwdriver method, but no spark.
It was running just last Saturday. Very frustrating!
Thank you for your help
 
New developments.
Just checked ballast resistor again and i am getting up to 5.5ohms!
Pulled a spark plug and grounded it, turned the engine over and i get an occasional spark.
Would a new resistor solve this issue?
 
I had the same exact problems you Speak of, crank but no start, shudder on key release like it wants to start, my problem was the reluctor to pickup gap went from .008 to .025 check that with a brass feeler gauge.
 
AAH!! Found the adjustment. She fired right up! Thank you all for your advice. I'm only a little excited! Woo!
 
EL5DEMON340 said:
I had the same exact problems you Speak of, crank but no start, shudder on key release like it wants to start, my problem was the reluctor to pickup gap went from .008 to .025 check that with a brass feeler gauge.
Click to expand...

SWEEET.
Good call there EL5
 
Nelson7604 said:
New developments.
Just checked ballast resistor again and i am getting up to 5.5ohms!
Click to expand...
The ballast resistor increases in resistance when it gets hot; it is supposed to do that. With 1.5 ohms cold and 5.5 ohms hot, you don't have the right one. There are several out there and parts guys never know the difference. The 'right' original ballast reads 0.5 to 0.6 ohms cold and a bit over 2 ohms hot. The next best is a BWD RU19 that reads about 1 ohm cold and about 3.5 ohms hot.

You can get NOS Mopar ballasts on eBay or try the MSD ballast from a place like Summit or Jegs that are around .8 ohms cold. The BWD can be gotten at Advance or O'Reilly but sometimes you have to order them; the BWD is the least expensvie, but I prefer to pay for the NOS Mopar; runs the best when cold with my old points ignition. High ballast resistances starve the coil of adequate current and reduce spark voltage.

When you measure low resistances like this, short the meter leads together first and read the lead resistance alone; then subtract that from the measurement to get the part's true resistance.
 
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