66 Mustang Ignition Resistor Wire Bypass

[@BlisterBang]

Thanks for the video! I have some minor corrections and explanations to add: The ignition wire (labeled "C" for "Coil" on schematics) is hot in both the ON and START positions of the ignition switch. When you switch to START the starter relay energizes the relay "I" post to bypass (or short) the resistance wire. This maximizes the voltage supplied to the coil. IOW, the points/coil supply becomes directly connected to the battery. When you release the switch to the ON position, the bypass is removed, but current flow is never interrupted because the normal power circuit was never opened by the ignition switch. We can debate whether this circuitry's purpose is to deal with battery voltage drop as the starter spins or to limit current flow through the points (and coil primary) when the engine is running to make it last longer.

[@RobertTSmith-hj5zt]

Thank you for adding this video. I’m adding a new Pertronix coil to my 1966 6 Cylinder and I know I have to bypass that resistor wire for my application as well. This helped clarify a few things for me.

[@ryanmcclendon3309]

Thanks for the video! I’ve watched several of your videos,skipped this one,thinking it didn’t pertain to anything I was doing..wrong! Was searching the symptoms.,and this video was a suggestion. I did a 5.0 swap a few years ago,with the original harness spliced with the mustang 5.0 and couldn’t find what was up with my starting issue. It starts on key release. Changed that resistance wire,perfect now. 🙏👍🏼🤙🏼

[@umangu]

Thanks for this video. The only one on this topic. I haven’t been able to locate the pink wire under my dash. My coil wire on the other side is a different color as well. Mine is red but yours is brown. Also my main disconnect is upside down to yours! Ford made it so hard I am most likely on a use to stock wire to trigger a relay and keep it simple for myself. Worried about messing up other things that are currently working. But thanks for the video anyway!

[@sasquachbigfoot9070]

What a great explanation, thank you. Just did my 1972 F100 pretty much all the same wiring. Wiring color code. I didn’t find bullet connector but assumed it was inside the original electrical tape wrapping and didn’t want to unwrap it, so with a tear in my eye I snipped the wire and ran a new wire all the way and directly to the new distributor that required a full 12v. Thanks again.

[@peteybrian]

Thanks for your explanation Mech. As I'm experimenting with upgrades - I'm learning more and more about terminology/parts names - and becoming more comfortable with the wiring. Fordsix Tech Articles shows us two ways of installing HEI's - but zero videos. Lol!

[@gregschmidt3620]

Great video. Can you clarify if we need to pigtail the resistor wire with a new wire directly to the + coil side ? Also the small brown wire on the solenoid has to be disconnected for it to crank over but will only fire after you let off the key to run position !! Can you give advice on the correct connection for the resistor & brown wire .thanks

[@T.Carrington-fg6fo]

Mech-best video yet on how to wire the EFI, and I get the bypass wire from ignition to harness, BUT (and I may have missed it) WHERE/HOW do I connect the pink wire coming from my Sniper EFI?

[@heathhenderson7217]

Thanks you for explaining this setup

[@TheBest-rg8sq]

Please could you help me with that I have in my car switch Battery positive wire Negative wire And ACC And On 1 And On 2 So the On2 it’s work and cut off when start the engine But the problem is doesn’t give me 12v positive at all and in my car scanner give me check the resistor and it’s PSP switch circuit error and resistance control module faulty Please and one help me with that

[@TroyCarroll509]

Why would you still need the 12V ignition wire hooked up on the starter solenoid when you have already bypassed the resistance wire with a 12V ignition source to the coil. That ignition wire from the ignition switch to the coil should be hot in both the start and run position and the ignition switch gets its power directly from the battery.

[@mechtrician1]

I don’t believe the ignition source is hot in the start position, but maybe it is. I don’t think I checked. But it doesn’t matter, doesn’t hurt having it hooked up.

[@TroyCarroll509]

@@mechtrician1 Yeah I wasn’t sure either so I checked and it is definitely hot in the start and run position. But that’s on my 1973 mustang and yours might be different. I only needed to know because I’ve upgraded my starter and it has the solenoid built onto the starter so I’m going to bypass the firewall solenoid and the primary resistance wire from the ignition and just run a regular wire to the ignition coil with 12 V from the ignition switch. Thanks for your response though. I really appreciate it.

[@stevodakine1]

I know with the early Mopar, when you get rid of your points you have to bypass the ballast resistor, it won’t run with it.

[@speedantiquities3641]

Ok stock 67 stock points distributor - how do I test resistance wire is working. You can not have a constant 12v to the coil correct? Or what component require you to use a resistor wire... I just replaced that portion of the harness with a cj pony kit oil pressure, temp, coil. Coil wire is thicker, but is it a resistor wire?

[@TroyCarroll509]

@@speedantiquities3641 you would have to test the resistance of that thicker wire from one point to the other in order to check to determine if it has a resistance. If it’s just a regular wire it will just show zero ohms or close to that. The reason for the resistor wire is to drop the voltage from 12 V to between 6 to 8 V because the stock coil is only capable of handling voltage in that range from 6 to 8 V. Otherwise you could upgrade to a 12 V coil like we did with no resistor wire in between just a standard wire and it should work just fine. That’s why Mopars have the ballast resistor in line rather than a resistance wire in order to drop the voltage to the 6 to 8 V range. But as I said before, you can always upgrade to a 12 V coil, eliminating the necessity for a resistor wire. Have a great day, my friend.