700r4 transmission plug

[Cdog_96]

Just installed new plug in 700r4 old one was toast. 87 Chevy v10 tbi. Saw the pink/black and the blue wire and I wired those right in, missing original wiring for the purple, any advice on where to look and what it's purpose is? I'm trying to clean up PO shoddy wiring, any help appreciated thanks !

 

[Jgonick]

purple goes to brake switch. It should cut power when brakes are pressed.

 

[Cdog_96]

How crucial is it ? And I see two switches that the brake pedal actuates? And does the purple wire come out of the bulkhead on the firewall?

 

[Jgonick]

does the purple wire come out of the bulkhead on the firewall?

according to wire diagram- yes My truck is an older model and is a little different.

I see two switches that the brake pedal actuates

Educated guess
One is probably brakes, the other is probably part of cruise control-which is usually also used for TCC (what you are looking for)-image

How crucial is it

gives power to TCC to lockup. Do you need it? people have several opinions. In town driving, probably not. Highway driving it would be good to have.