Anyone recognize this plug? It is in the path of the ignition wire to the coil.

[Yellow Truck]

I'm going to pull some new wires as the insulation on the old ignition wire is starting to break down. This is where the wire to the coil ends up under the dash. I've been through my shop manuals and they make no note of this part. Looks like a factory part, moulded onto the wires, with 4 input wires but only 3 outputs.

There is no evidence there ever was a fourth output wired, the thing is moulded for three. What would it be doing inside the plug?

I have not tried to separate the two parts - some of these old things just crumble - and I thought I'd ask before I cut the wires downstream from it.

[Yellow Truck]

I seem to have stumped you all. Got an answer on the Ford-Truck forum for those who might be curious - I looked in my shop manuals but I don't have the wiring, someone pointed me at this:
http://fordification.com/tech/wiring/wiring-1969charging2.jpg

Someone else explained it is 4 to 3 since the coil wire is initially fed from the starter solenoid and then when you release the key it is fed from the resistor wire.

Leads to the next question - does the MSD 6AL and distributor work well with the resistor wire or do I need to change the 12V source.

[jayb]

You don't want the resistor wire triggering the MSD.  Run a switched 12V wire to the small red wire on the MSD.

[chris401]

I'm going to pull some new wires as the insulation on the old ignition wire is starting to break down. This is where the wire to the coil ends up under the dash. I've been through my shop manuals and they make no note of this part. Looks like a factory part, moulded onto the wires, with 4 input wires but only 3 outputs.

There is no evidence there ever was a fourth output wired, the thing is moulded for three. What would it be doing inside the plug?

I have not tried to separate the two parts - some of these old things just crumble - and I thought I'd ask before I cut the wires downstream from it.

If we are on the same page those two wires together are going to the same circuit. More than likely it is like other Fords and the start full 12 volts is on one leg and the other is the resistor wire. Both go to the positive coil terminal.

If it is for the truck pictured those are both 12v start and run wires feeding into a single resistor wire

[Yellow Truck]

You don't want the resistor wire triggering the MSD.  Run a switched 12V wire to the small red wire on the MSD.

Thanks Jay. MSD tech support said it was ok to run it, but I tend not to trust the tech lines. I'm sure they are fine for SBC questions, but I have doubts about anything else.

I get to spend more time under the dash today!

[jayb]

I'm surprised MSD tech support said that.  The very first time I ran an MSD it wouldn't work until I bypassed the resistor wire.  That was a long time ago, so maybe the newer models have changed things...

[Yellow Truck]

I phoned this morning and emailed last night. On the phone the guy had a really hard time expressing himself (great hire for phone support, kind of like hiring a blind chauffeur), but the email that came in after you replied said it had to be bypassed.

Will dive under the dash later today. Studying the wiring diagram I see that the wire labelled 262 runs from that plug to the starter relay. Not knowing how the ignition switch works - if I run a new wire from the ignition key assembly direct to the coil do I dispense with the wire from the starter relay?