Where does this set of wires go?

[DanMcG]

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I'm trying to help someone figure out what these wires do on his 84 half ton. He only has one side of the connector which looks to be coming out of the main harness between the motor and firewall.
on my 85 k10 I have the same connector as shown in the pic which goes thru the firewall ( to the left of my fingers) but once inside I can't find it. it should be just above the heater box but the mice got it packed in tight with insulation and I can't trace it. where does it go? maybe to the ECM or is it ESC?

It looks like purple, green, gray and black wires.
I've looked the wiring diagrams with no luck.
thanks.

 

[Swearbody]

OOOH the dreaded esc. It is a part of the distributor. I have a video on how to delete if you want to see it. You want to remove it asap.

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THere is a hand written diagram around 5:50 in the video. It is probably the most helpful part of the video for understanding the actual plug itself

 

[DanMcG]

Haha Jeff, I just finished reading the post and watching your video, Thank you Sir!

 

[Swearbody]

Haha Jeff, I just finished reading the post and watching your video, Thank you Sir!

Yes sir. Glad I could help.

 

[fast68chevy]

best way to go if it doesnnnt have vacuum advance is to swap a vac advance HEI ditrib in place of it.. but you can keep it and jump the one and three location wires goether to bypass/stop the retard timing function and it would be good to good then.