I've got a 75 F-250 with a 460 that I'm in the process of swapping out the old Duraspark 1 distributor, green 7 wire ICM and harness for the Duraspark 2 distributor, coil, harness from a 78 F350 that had a 460 and a Motorcraft 6 wire blue ICM. As of now I've got the new distributor in place and verified TDC compression stroke on cylinder number 1and balancer is at 0* and all the plug wires are in the correct positions on the cap. I've Googled and looked all over these forums and I can't find what I'm looking for. I'm trying to figure out what to do with the 3 wires coming from the plug that connects to the 2 wire ICM? What should the white wire from the module connect to and what should the red wire of module be connected to? The way it sits now I can turn the key to the "RUN" position and my coil is reading ~6v which should be correct? The problem is when I crank it over it's not wanting to pop off and when it does pop it sounds like it's running on 2 cylinders and tries to idle at what seems like 100rpm then dies or backfires through the carb. I'm not really good at reading the electrical diagrams with their symbols and I've read enough posts that all that information has scrambled my brain. I just really need to know what to hook up to the red and white wires first. Thanks for any help I can get.

 

 

So I need to tie into the brown wire from the "I" side of the solenoid to the white wire? The pic is small so when I expand it,it goes blurry.

 

Let me see if I can find a better diagram. I know one of the two white or red goes to power and one to ign crank power but can never remember which one. I had the same issue with the pic.

 

 

And you want the box's hot-when-cranking-starter wire connected to the "I" post on the starter relay/solenoid. If you connect it anywhere else which is hot during cranking, you could have a starter run-on condition. That happened to me on my old '68 Cougar. For whatever reason, I connected it to the starter trigger wire/S post, and my starter would sometimes run away, and I'd have to disconnect the battery to stop it.
Once I connected that wire to the I post, the system worked flawlessly.

There is a diode in the solenoid, which prevents back-feeding power, and prevents starter run-on.

 

Thanks for the replies everyone. I've been working on these trucks for 32 years but I struggle with electrical diagrams.

 

So I should be able to make a wire that hooks to the "I" on the solenoid and run it straight to the white wire coming out of the box? I hope that's what I need to do, if that's it I have been WAY overthinking this and just confusing myself even more.

 

It's been close to twenty years since I messed with it, and I put the points setup back on when I sold the car.
With the power wires, you have the Run input, and the Cranking input.
Cranking is what goes to the "I" post, but I don't remember where I connected Run. I don't know if Run is connected to straight 12V+, or if it gets connected to a resistor circuit, and should be receiving less than 12 volts. Maybe the box steps down the Run voltage to the coil?
I'm pretty sure I connected my box's Run wire to the positive wire running to the original coil on the old Cougar, which would be less than 12 volts. It worked perfectly and ran good, but I'm not sure if it was correct.

 

The Blue module does not "need" a resistor in any of it's wires, but it probably would still work if it happened to be connected that way.
The START signal can come from either the "I" wire of the starter relay, OR it can take it from the Red w/blue wire from the ignition switch. If your original cab-side connector has a Red w/blue wire, then use that for the White wire of the module. The Red w/green wire is for the new Red wire.
Your '75 might have used a Blue wire in that connector. If so, that is the equivalent of the Red w/green wire and should be used in lieu of a Red w/green wire.

The Brown "I" wire from the starter relay probably only powers the ignition coil when in START. At least on older trucks the Brown wire terminated at the Red w/green wire behind the engine. Maybe ford tapped into it there, or maybe they tapped into the Red w/blue wire from the ignition switch. Probably simpler for them to do that instead.

Just for filling in the blanks, does your original harness have just the two wires in a 3-wire connector, or does it actually have all three?

Paul

 

It's got all 3 wires coming from the harness plug. I've got it up and running now, the conversion made a big difference.

 

To get this up and running after I converted over to the Duraspark 2 distributor and the Blue ICM I ended up with the Green wire from the main harness to the RED wire coming from the ICM and I ended up running a wire from my "S" post on the starter solenoid to the white wire from the ICM. I checked the voltage at the coil with the engine off and key in "Run" and I've got ~ 6.8V and when the engine is running I've got ~ 7.1V. Everything is working great and it's been almost 2 weeks.

 

I picked up a NOS NAPA/Echlin TP 40 (blue grommet) module as a spare. This note was in the box;

 

I went from 7 wires to 6 wires but it's not just plug and play.