Whats This???

[1great68]

Hey all I have a 85 k10 and was wondering what this is on the ps firewall?

[J Knight]

I think that controls your torque converter lock up.

[1great68]

Well thats nice to know! On my truck that vacuum line dont go to anything! It looks like it supposed to have another little plastic piece on the vacuum line but i cant tell what it is cause it got melted on my exhaust manifold. Is that vacuum line supposed to go to the trans??

[rwhit57]

No that line goes to a vacuum source. It might have had a tee in it supplying vacuum to something else. That switch is used for something else also but I can't remember what it is, the uh umm ok somebody help. Sometimes there are two of those one goes to the tranny lockup and the other is that other thing.

[1great68]

so with that vacuum line not being hooked up is it going to hurt anything???

[joe231]

If you have a lock up torque converter, it won't lock with out vacuum.
Posted via Mobile Device

[gchemist]

First there are two of those "thingys". The driverside one controls the torque converter lockup. It must have a vacuum source. The passengerside one controls timing. If you follow the wiring harness, it goes the ECM behind the glove box. The other wires go to the distributor. Now if you only have one and a 350THC or 700R4, it's for the torque converter lock.

[Junqueboi]

Yeah, it's called a 'Vacuum Tip-In Switch". As the previous poster mentioned, it's part of the ESC. I believe it closes its contacts (or opens them?) when it senses a sudden drop in vacuum this is when the throttle is opened quickly.

As a result, the ESC module retards the timing a bit to prevent detonation. I believe ESC (& this switch was only used on 305-equipped vehicles.

The TCC vacuum switch is on the driver's side of the firewall, very close the the Brake Booster/master cylinder.

[1great68]

Mine had a 305 in it but now has a 350, so the one on the drivers side is the lock-up switch then??? Thanks for all the help!!!

[Junqueboi]

Originally Posted by 1great68

Mine had a 305 in it but now has a 350, so the one on the drivers side is the lock-up switch then??? Thanks for all the help!!!

Right, the one on the driver's side should be the lockup switch. It's also a little bit smaller than the Tip-In switch on the trucks/vans I have seen & worked on. Have fun

[Smoke_Dog]

I had a 305 also! Then I guess it's the same for me also! Do U have and pictures of the otherside, because I have another hose also that I'm inquiring about. Will post picture's tomorrow! Junqueboi, do U have any pictures of what on the back fire wall?
http://67-72chevytrucks.com/vboard/s...d.php?t=504930

Originally Posted by Junqueboi

Right, the one on the driver's side should be the lockup switch. It's also a little bit smaller than the Tip-In switch on the trucks/vans I have seen & worked on. Have fun

[Junqueboi]

Originally Posted by Smoke_Dog

I had a 305 also! Then I guess it's the same for me also! Do U have and pictures of the otherside, because I have another hose also that I'm inquiring about. Will post picture's tomorrow! Junqueboi, do U have any pictures of what on the back fire wall?
http://67-72chevytrucks.com/vboard/s...d.php?t=504930

Hey Smoke_Dog,

I work from home tomorrow & will take a few pics of the other side & post them. It will be late tomorrow afternoon though and they will be crappy cell-phone pics. Pics will be from an '86 C10 or C20 (whichever ones show up better!)

[Smoke_Dog]

OK. I took some pictures also today and I found the other one! it's still connected but the one on the passenger side is also, but there's one hose after it goes in the vaccum hose outlet on the intake at the rear it's not connected is it needed?

Originally Posted by Junqueboi

Hey Smoke_Dog,

I work from home tomorrow & will take a few pics of the other side & post them. It will be late tomorrow afternoon though and they will be crappy cell-phone pics. Pics will be from an '86 C10 or C20 (whichever ones show up better!)

[Smoke_Dog]

Posted updated pictures on my thread! Just incase U wanted to look!!!!

http://67-72chevytrucks.com/vboard/s...d.php?t=504930

[Junqueboi]

Originally Posted by Smoke_Dog

Posted updated pictures on my thread! Just incase U wanted to look!!!!

http://67-72chevytrucks.com/vboard/s...d.php?t=504930

Cool..I'll post pics over there then, LOL...

[camshaftgsxr]

Originally Posted by gchemist

First there are two of those "thingys". The driverside one controls the torque converter lockup. It must have a vacuum source. The passengerside one controls timing. If you follow the wiring harness, it goes the ECM behind the glove box. The other wires go to the distributor. Now if you only have one and a 350THC or 700R4, it's for the torque converter lock.

ive always been wondering what the passenger side one is, thanks

[bowtiemanchevyman]

it a earily version MAP sensor to help get better MGP and emission