Tell me about your ballast resistor failure.

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cruiser said:
Guys: I'm interested in learning how many of you have had a ballast resistor failure in your ride. What happened when it failed? Did everything die, or just the ignition system? How long did your ballast last before it failed. How did you know it failed? Any and all inputs welcomed. Thanks!
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My '74 Valiant suddenly died last month 3 times in a distance of like 2 miles or so. Started back up again but it died 1min after again.
She started right up when the engine was cold.
I think it might be the ballast resistor because... I mean look at it. It also still has the OEM part number so I think it is time to replace it.

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Hate to say it but just because the porcelain is cracked doesn't mean the resistor is bad. Given that, I would probably replace that one just because even if it works it just plain looks bad.
I have to say that this part gets talked about lots, and definitely gets blamed for many things it can't possibly cause. Your engine may well die when it goes bad.
usually I've seen it where you get home, shut them off, and later when you go to get in and go somewhere else the engine won't start. Or more likely it will but will die as soon as you release the key from "START".
I've also seen ignition switches die with same symptoms but not as often as the ballast. (and the ballast never did die as often as it got blamed for in the first place, either )

If it blows, there's no way its gonna start up and you continue down the road a couple miles and die again.
and the one that some wiper motors have, doesn't have anything to do with the ignition.
 
Bewy said:
That is why the fully enclosed/sealed BRs are better. A good thump or bump can break the brittle former the wire is wound on. The Nichrome wire also becomes brittle over time from so many heating/cooling cycles.
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So why did Ma Mopar keep the .5 OHM Coil side of the dual ballast resistor open when they first developed the electronic ignition

Then at some point in the mid 70s switched the Coil side of the dual ballast resistor to 1.2 OHM and sealed it

Same Mopar Part # Dual Ballast Resistor
First is .5 OHM Coil Side Open

Second is 1.2 OHM Coil Side Sealed

No Jobber or Aftermarket sells a Dual Ballast Resistor with an .5 OHM Coil Side Resistor





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I personally never had one fail, even before I got my car from my grandfather in 1985 my grandfather told be the story of when it died on him.

He was on a road trip and was about a hour out and that put him pretty much thirty minutes from anything, car died. He ether was good at troubleshooting or had a reason to suspect it was the ballast. He took a gum wrapper (at that time they were foil) folded it up and stuck it between the terminals. It worked for the 30 miles or so he needed to go to get to a parts store. Years later and after i got the car I found a receipt for it in the paperwork, 1971.


Alan
 
bee1971 said:
So why did Ma Mopar keep the .5 OHM Coil side of the dual ballast resistor open when they first developed the electronic ignition

Then at some point in the mid 70s switched the Coil side of the dual ballast resistor to 1.2 OHM and sealed it
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Good question.
If we knew what year, there's probably a bulletin.
My initial guess would be lean burn, but you say its the same p/n, which would certainly be changed with a new design.
 
I don’t ever remember any other ballast resistor other than the common dual ballast resistor back in the day. The half ohm was points and the 1.2 was electronic. The ignition systems were designed as “systems”, so changing parts can be problematic. What is really important is the current through the coil rather than the voltage applied. However, the current is hard to measure without more sophisticated equipment, so everyone usually talks about voltage.

If you see a damaged part, that is usually a good place to start troubleshooting. I don’t know how many times I have come up with a complicated theory for a failure, only to find a blown fuse later….
 
What year did they switch from a dual ballast to a single, and what did they change in the rest of the wiring loom to allow this?
 
Any increase in the compensating ballast's resistance must be after 1976
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volaredon said:
What year did they switch from a dual ballast to a single, and what did they change in the rest of the wiring loom to allow this?
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I'm pretty sure it came in with the electronic ignition.
The wiring difference is basic. Input tied (Ign1 - blue), output to ignition module and coil.
PD452.jpg



Alan
 
Yes , I have an original 3656199 Dual Ballast Resistor in my stash for electronic ignition
Came off a factory 1973 Dodge Charger

It also is .5 OHM on the coil side of the Dual Ballast Resistor

Then that part # was replaced or superseded with the Dual Ballast Resistor that I have pictured

Same part #s , different OHM Ratings on the coil side of the Dual Ballast Resistor clearly in pictures

.5 OHM open
Normal Side in that diagram below

"On one side is the half-ohm ballast resistor that is the same as in a breaker-point sys-
tem. It maintains constant primary current with variations in engine speed."

1.2 OHM sealed later on , you mentioned 1976

Thanx



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The Nichrome wire gets brittle from the hot/cold cycles it goes through in operation. An analogy is a fuse that is run close to it's rated value. The wire gets hot & it eventually breaks....it does not blow from a current surge. It fails from metal fatigue.

The Nichrome wire is wound on a former to help support it; cavity is then filled with ceramic paste for further protection against vibration/failure. Why some are filled & some not....
Do not know. QC issue?
 
Dana67Dart said:
56 years and 324,000 miles, still going strong.
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Only reason I changed the one on Vixen was when I changed to electronic ignition. I took the original one off. Still have it in my organizer. It's still good.
 
volaredon said:
Hate to say it but just because the porcelain is cracked doesn't mean the resistor is bad. Given that, I would probably replace that one just because even if it works it just plain looks bad.
I have to say that this part gets talked about lots, and definitely gets blamed for many things it can't possibly cause. Your engine may well die when it goes bad.
usually I've seen it where you get home, shut them off, and later when you go to get in and go somewhere else the engine won't start. Or more likely it will but will die as soon as you release the key from "START".
I've also seen ignition switches die with same symptoms but not as often as the ballast. (and the ballast never did die as often as it got blamed for in the first place, either )

If it blows, there's no way its gonna start up and you continue down the road a couple miles and die again.
and the one that some wiper motors have, doesn't have anything to do with the ignition.
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Well the connector pin thing (I have no idea what it is called) is a bit loose due to the crack so I can move it a little bit which might cause a sudden interruption.
I can't post the video I've made...
 
Maybe we should swap ours out for the ballast resistors that GM and Ford uses. Theirs never seem to fail.
 
SlantedMark4 said:
Well the connector pin thing (I have no idea what it is called) is a bit loose due to the crack so I can move it a little bit which might cause a sudden interruption.
I can't post the video I've made...
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I've finally found motivation to check it.

Ohms were a bit high at 5.9 to 1.9-2.2, the replacement is 5.5 to 1.8. The old one was at 17.7 once instead of 5 but this might have been a faulty measurement.
The difference from old to new is low but I've changed it anyway cuz the old one was a bit... crumbly and already 50 years old.
(No I didn't pull the plug like I'd start up a lawnmower. It was already wobbly when I've inspected it last week).

I'm now gonna order two of those ignition switches you guys mentioned, just in case.


Ah yes, OEM part number is 3656199, replacement is an SMP-RU12. I've ordered 2 similar resistors, both read exactly the same if anyone wanna know.

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Mike69cuda said:
I used to carry extras in the glove box in my youth. They failed pretty frequently in the 70s.

When they fail, the car will start, but as soon as you let off the key it will die.
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I never had one fail on my own cars. But did change a few on friends cars.
Once was due to a bad alt.
One had some other part fail and it took it out, and fuseable link. I can't remember what parts it was.
Was a,sacrafial lamb I guess
 
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