Anyone ever get a ballast resistor that was assembled backwards from the factory?

[troyintahoe]

I was working on my rescued roadrunner today. It has been cutting out abouve 3,000 rpm's. I got a timing light on it today and noticed the light was cutting out above 3,000 rpm. Started checking with the Ohm meter. Coil was not putting out proper.

Discovered my ballast resistor was assembled from the factory backwards!

I cut the dowels off of each of the two prong plugs for the resistor. Plugged them in backwards and bingo! My harness had never been tampered with, so I guess the only possibility was the resistor was built backwards, from the factory.

If you plugged into the resistor either way with the little dowel in the slot the correct way, It would not work properly.

It was an O'rilley part, buy the way. Crazy......................

Anyone else ever have this happen, or am I the only one? Troy

 

[Meep-Meep]

A resistor doesn't care which direction it's hooked up. Only thing I can think of is if you have two different resistor values and the wrong resistor was being used for the function, then that will affect the voltage. Maybe that's what you're saying?

 

[72 Charger SE]

I would question whether there was a mistake from the factory on that ballast resistor wiring, seeing as the car is now over 30 years old. Surely SOMEBODY would have figured it out before now, hopefully the dealer service department when the car ran like crap NEW.

More likely is someone messed with the wiring in some way that is not obvious at first glance. Even more likely is your ballast resistor has gone bad and now you are running the car on the start side of the resistor, and somehow are lucky enough to start it using the bad run side.

Have you tried a new ballast resistor? They don't last forever. I've seen a couple go bad over the years, one on my Charger, and one on my truck when my dad owned it. I always carried a spare after the truck fried one, although we were able to get back to civilization using a jumper wire at the resistor.

 

[troyintahoe]

Ballast

This is a brand new ballast resistor I bought from O'riley's.

The original looked hammered, so I replaced it about a year ago. I just got the car running well enough for a test drive.

No matter how I plugged it in, the car would run out of spark at around 3,000 rpm. Now that I cut the dowels, and plugged them in upside down, the car runs like a champ. The original harness looks untouched. ????? Troy

 

[72 Charger SE]

My best guess would be something wired wrong then. Or possibly something else in the run side of the ignition circuit that is adding resistance and reducing voltage.

Unless you know first hand the history of your car, don't assume that anything is unmolested or done right. I had a car once that the only things that were done right, the previous owner had receipts to prove that someone other than he did the work.

 

[troyintahoe]

Ballast

Thanks for the imput. I will do some more searching and testing as I have time. Didn't seem right to me either, but I thought maybe the ballast was put toghther backwards.

I have no clue on the history of this car. It hadn't ran in ten years, before I got ahold of it. Troy

 

[69 Runner]

Resistors are not polarity sensitive. It couldn't have been built "backwards". It could, however, be a totally incorrect VALUE and cause voltage to drop across it more than intended

 

[LonleyDuster]

I think he means upside down. It's a four pole resistor? Actually two resistors on the same insulator. On my A body the top resistor is for the coil, the bottom for low speed on the wipers, I think. The resistor insulator is "keyed" to bolt to the firewall only one way. He is saying that the manufacter put the wrong value resistor on the top and bottom.

With the wrong value on top, you get about 3.5 volts to the coil. Barely enough to idle, but thats it.

Yes!! I have had one like this! From O'reilly's. It only took me two weekends of troubleshooting to figure it out. (awesome "aha" moment). They won't get me with that one anymore.

 

[daredevil]

I think he means upside down. It's a four pole resistor? Actually two resistors on the same insulator. On my A body the top resistor is for the coil, the bottom for low speed on the wipers, I think. The resistor insulator is "keyed" to bolt to the firewall only one way. He is saying that the manufacter put the wrong value resistor on the top and bottom.

With the wrong value on top, you get about 3.5 volts to the coil. Barely enough to idle, but thats it.

Yes!! I have had one like this! From O'reilly's. It only took me two weekends of troubleshooting to figure it out. (awesome "aha" moment). They won't get me with that one anymore.

thats good info to know

 

[scotts74birds]

Rang out a new on in the box. The top resistor is 1.5 ohms, bottom is 5.5 ohms. Dont have a good schematic in front of me to tell you which is for the coil. What Lonelyduster said makes perfect sense.

 

[troyintahoe]

Ballast resistor

Yes! It was upside down. I guess I just labelled the thread wrong.


So, if your car is stumbling after relacing the ballast resistor, make sure and look for this. This was a brand new resistor from Oreily's/ Kragen Auto Parts. Troy

P.S. My car is running great now........................