86 F150 straight six TFI to HEI

[tanman]

I’ve posted about my TFI module failing multiple times when it gets too hot. I am planning several changes to the engine and will be starting with the ignition. I will be installing the DUI distributor.

I want to document this for others to learn from my success/ failure.

I have planned out the wiring but I don’t know which wire to “control” the relay. The 12V will come from the factory accessory “yellow” wire next to the brake booster. The fuse and relay will mount to driver inner fender.

[tanman]

[ArdWrknTrk]

I think you should use the red wire going to the ignition coil.
The yellow wire is constant power.
How would you turn off the vehicle?

[tanman]

This wire is my planned 12V supply. This wire was pointed out in another section of this site “ignition simplification” I think. Thanks to Gary.

[tanman]

I can’t clearly see a red wire going to the coil. I assume the coil is that gray thing on the left that looks like a transformer.

[tanman]

If you meant the red wire on the relay... it is my understanding that pin 86 switches power from pin 30 to pin 87. I guess 86 should be ignition but that’s way on the other side.

[Gary Lewis]

I think I'd use the White/Light Blue wire that powered the TFI module & coil to pull in the relay.

[FuzzFace2]

tanman wrote

This wire is my planned 12V supply. This wire was pointed out in another section of this site “ignition simplification” I think. Thanks to Gary.

Only thing I would worry using that wire if you dont use one Gary pointed out,
Does it still have power when the key is in the ACC.
If so I would not use it as the HEI will be powered up other than when the key is off.
Dave ----

[ArdWrknTrk]

Ooops.  No I meant the red wire that would power the module in a DSII system.

It was my understanding that the basic harness is the same for both DSII & EEC trucks, so I thought the plug with white and red wires would be present.

That wire should have power in both start and run, but not accy.
As Gary points out you could always use the EEC coil power wire as well.

[Weberman]

On my set up, I bought a super cheap DSII and cut the wires off as close I can to still have a plug in harness. But that is what I did, took the red wire that goes to the module as it has it in crank and run like stated. I actually took it and made it go to a relay, that controls my engine run accessories, like my fuel pump, HEI module, the coil, electric choke, etc. But the TFI coil should have full 12v so you can run it off of there.