Ballast Resistor and Starter Burning Up.

[59bisquik]

Having some frustrating issues with my new Mopar electronic ignition. Since being hooked up according to the schematic, I am burning up ballast resistors as soon as it goes into run mode. Also, the starter hung up and burnt up my new Powermaster starter.

My theory is, when in start mode, the 12v bypasses the ballast resistor and gives a full 12v to the coil. Also in the same circuit is the starter solenoid getting a 12v signal. As soon as the engine starts and the key goes to run, the 12v goes through the ballast resistor and cuts the voltage down to 6v  for the coil, but is also backfeeding 6v to the starter. Does this sound like a reason to kill the ballast resistor and keep the starter solenoid engaged? The resistor definitely isn’t designed to run the coil and solenoid.

I am thinking once my new starter gets here this week (overnight shipping) I will place a diode in the starter solenoid wiring so the voltage cannot feed through the resistor and overload it. Thoughts?

 

 

[mechresto]

Just an observation...

Check your switch wiring to make doubly sure you don't have 2 "hots" feeding your ign/start circuit.

If its got that, when coming off "start" and back to "run" it will re-engage the solenoid and the ballast.

Thoughts?

It's not entirely uncommon...

[59bisquik]

I replaced the start switch with a new one since my stock switch had some resistance on the ignition pole. Still the same issue.

 

if I jump out the ballast resistor and give the coil 12v all the time it also runs fine, but I know that’s hard on the coil.

[kencombs]

Not an expert, but it sounds to me like the wiring is incorrect.   The S wire should not go the a terminal on the solenoid that provides the current to engage the solenoid.  Post a pic of the solenoid in use. 

 

 

 

s

[59bisquik]

The wire going to the S terminal also has a wire going to the starter solenoid. On the Powermaster gear reduction starter, the solenoid is built in. 

I am going to double check the wiring tonight.

[kencombs]

I think you need a relay to send 12v to the coil when the starter is activated, not a direct connection.  On older Fords and some Mopars there was a starter relay that had two small posts, one to engage the relay and one to to coil.  With your starter you could use a common head light relay to do that.  Or, if your connections are available, you can use the post that is only hot when the starter is running.  Again a pic is worth a thousand words.

[59bisquik]

This is the starter I am using. Just running a 14ga wire down to the solenoid terminal to activate the starter. This wire and the start wire to the coil are on the same terminal on the ignition switch.

[kencombs]

Yeah, I see your problem.  You definitely need a means to send 12v to the coil when starter activated, but with no continuity from coil to starter solenoid pull in coil when not in start position.

 

A relay is the right answer IMO.  I think Mopars in the 80s/90s used such.  Or you can just use a simple headlight relay from the parts store. 

 

Or, replace the Mopar ECU with a GM HEI module and the wiring is really simplified, not need for the resistor or bypass wiring.  Better/hotter spark and dwell control too.  GM on a Mopar:  blasphemy I know but in this case it may be better.

 

Somewhere on this site is a how to on that.  Some guys have used the slant 6 electronic distributor, with mods of course, to run there flatties and used the GM module.  That's  my plan at the moment for my '56 1/2T.

[59bisquik]

Ken,

   Thanks for the help. I am going to go home tonight and double check my wiring again. I also ordered 2 ballast resistors today and some diodes. If I put a diode in the feed to the brown wire, it wont let voltage go back to the switch when in Run mode. Thats the easiest,  but if that doesnt work, a relay as you suggested will be next.

 

As for the slant 6 distributor, I dont think it will work on my setup!

 

Edited April 11, 2018 by 59bisquik

[kencombs]

No, I didn't suggest the 6 distributor, it's just that your distributor's reluctor does the same thing and will drive a GM module without any need for a resistor or relay or special wiring.

[59bisquik]

13 minutes ago, kencombs said:

No, I didn't suggest the 6 distributor, it's just that your distributor's reluctor does the same thing and will drive a GM module without any need for a resistor or relay or special wiring.

Lol... I was just having fun with you! 

[kencombs]

FYI, the relay Mopar used for this function is a Standard Motor Parts SR105.  Should be able to find that at any parts store.  And, it's almost guaranteed to do what you need.  Not so sure about a diode in a potentially high current situation.

[59bisquik]

So you are saying wire the system with a relay like this? I will run down and see if they have this relay.

[kencombs]

That's it!

[59bisquik]

HUGE THANKS TO KEN!!!

I installed the relay as suggested and also added the diode into the start circuit as I originally planned. It fired right up and runs good. Coil stays cool and the resistor is also cool.

Edited April 13, 2018 by 59bisquik

[Adam H P15 D30]

I also agree to go to the GM HEI module. You will get a hotter spark, better dwell control and best of all, you can get rid of that troublesome ballast resistor. 

If not, like most MOPAR people, keep a spare resistor in you glove box. 

 

Adam