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View Full Version : Removing ballast resistor - starter connection



sith33
06-05-2023, 04:38 PM
Howdy all - just want to double check something. 86 D50 2.0. I'm thinking of swapping to a newer coil with an integrated resistor. On one side of the resistor, there's a black-red wire that goes to the starter. On the other side, there's a black-white coming from the ignition, which is jumped to the coil itself (and the B/W to the distributor).

When removing the resistor, do you just tie all of those together? So coil (+) ends up with two B/W, and B/R, coil (-) ends up with white/blue?

SubGothius
06-05-2023, 10:55 PM
The black+red-stripe wire only gets power when cranking the starter, and should be connected to the ballast resistor terminal that's also jumped directly to the coil (+) terminal. This arrangement bypasses the ballast resistor during cranking to give the spark a bit more oomph for initial startup.

The black+white-stripe wires get power whenever the key is in the Run position. This feeds power to the coil through the ballast resistor, which reduces the voltage to the coil during normal running to prevent burning out other ignition components prematurely.

The blue wire to the ICM (or older-style points) in the distributor should connect to the coil (-) terminal, where the white wire for the tachometer is also connected.

You may also have an RF noise-suppressing capacitor (tiny black plastic box or metal cylinder) with two wires, one connected to the ballast Run terminal (w/ the black+white wires) and the other to ground.

I like the Herko B108 coil I got for my '87 a few years ago:
https://www.ebay.com/itm/381825243549

Here's how I have that wired up, but note I dis/reassembled the mounting bracket to flip the coil around for easier/tidier wire routing:

http://www.mightyram50.net/vbulletin/attachment.php?attachmentid=27863&stc=1

sith33
06-06-2023, 07:43 AM
Thanks - that makes more sense, and agrees with the wiring diagram. I think mine is just hooked up wrong.

So, for a coil with an integrated resistor, it seems safe to just attach all the BW/BR leads to the positive and go for it.

SubGothius
06-06-2023, 04:07 PM
Yeah, sounds like a PO just jumped the coil (+) terminal to the wrong end of the ballast resistor.

With an integrated ballast, you could prolly just skip connecting the B/R wire altogether, not sure if it would do any harm to hook it up to the coil (+) terminal anyway tho', might contact the mfr./vendor to ask about that.