new ballast resistor died in 10 minutes

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rigger3006

rigger3006

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installed new voltage regulator and new ballast resistor at same time, engine started dying after 10 min run time, cooled it down, same thing again, put 10 yr old resistor back on and it runs fine. I think I read somewhere after this they are supposed to be done separately, something about burning in the new regulator first? any thoughts or experience with this or maybe it was just a bum resistor?
 
ballast resistor was off ebay, supposedly NOS, in mopar box, yep probably gonna switch to more foolproof system not sure which way to go though
 
The Vreg circuit is independent of the ignition, other than both get power from the key switch. Changing one thing at a time is always smart. If Vreg didn't work, your battery wouldn't stay charged.

To trouble-shoot the ballast, measure the voltage at coil+ (w/ blk lead on BATT-). The ballast should drop it from BATT+ to ~8 V when running. If you have a dual ballast, you also need to check the wire going to the ECU, but it should also be a bit less than BATT+. Insure your ECU has a good ground to the case (a rusty screw isn't).
 
In 1977, my mother gave me her 1968 Dart. Just to be safe, I replaced the original, nine year old Ballast Resistor, with a new one - not Mopar, but Canadian Tire. I drove about four blocks, and it died. I put the original back in, and drove it, until I sold the Dart, in 1982.
 
Use a voltmeter to check the battery voltage at fast idle and warmed up. It should read in the 13.7-14.2 voltt range. If it is a lot higher, then that would stress the ballast (and everything else). Any such overvoltage condition needs to corrected ASAP. I bring this up as you replaced thr VR for some reason and you could have charging system issues that remain unresolved. Unless you measure the charging battery voltage while running at fast idle, or kinow how to observe the ammeter and work from that, then you don't know if the charging circuit is right.

Also, be aware that the stock ballast resistors cam in 2 different resistances. So you might have the wrong NOS one.

Was this a /6 or V8 or what? And is this the stock coil? Year and model car?
 
318 in 72 demon, 4 pin resistor, did the change over strictly for cosmetic reasons, msd blaster 2 coil
 
Since it is a 4 pin, did you observe the orientation of the resistor? The resistance in the 2 halves is different. There is a nub or gap in the back that should only allow it to mount one way. If the high resistance half was accidentally put in series with the coil (instead of in series with one of the wires to the ECU module), then that half would get too hot.

For 1972, do you have a Mopar ECU and distributor? I ask since you put in a 4 pin ballast.
 
chrome ecu andmopar distributor, resistor was mounted correctly, actually I may have had my firecore 50 distributor in at that time, cant remember! with the firecore engine runs out of steam at 5600 rpm , the mopar distributor she"ll rev to 7000 so Im sticking with it and gonna put the firecore in my truck
 
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