What is this??? And where does it go

[82goodlymadechevy]

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Hello I need your guys help yet again. It mounts to that hole on the firewall and you can see the plug dangling there i dont know what it is?or what it is for? if its even necessary? And where does the vaccum line go to on the engine? Thankyou for all the help

 

[PrairieDrifter]

It's part of the torque convertor lockup system for a 700r4. I'm pretty sure it's supplied by manifold vacuum, I'd have to double check though.

Edit- I'm almost positive it's ported vacuum. NOT manifold.

 

[82goodlymadechevy]

thankyou prairie so it wouldnt matter much for a turbo 350 im assuming i could get arid of it in that case?

 

[PrairieDrifter]

thankyou prairie so it wouldnt matter much for a turbo 350 im assuming i could get arid of it in that case?

Yep you wouldn't need it. Does your gear indicator have four or three speeds?

I'm not well versed in them but it could be a th350c with torque converter lockup. I'm not sure how they controlled the lockup on those though. I would imagine it would be similar.

82 would be first year of the 700r4 as far as I know.

 

[BadBowtie]

Don't get rid of it. It is also used for the lock-up signal on a TH350-C transmission!!!

 

[82goodlymadechevy]

sorry for the late response the gear shifter has 3 spots and i didn't see the plug on the side of the tranny for the 350c version i am assuming it has been swapped. wouldn't the plug for the connector be on drivers side? also the torque converter locking up is not a big issue for me it will rarely reach 60 miles an hour all back roads around here

 

[82goodlymadechevy]

I read it could possibly be something with the electronic spark control? Does that sound right? I was going to run it with it off and then hook it up to see if it made a difference

 

[Turbo4whl]

thankyou prairie so it wouldnt matter much for a turbo 350 im assuming i could get arid of it in that case?

If your truck has that vacuum "tip-in" switch, then yes the truck would have, or have had, the Turbo350C.

sorry for the late response the gear shifter has 3 spots and i didn't see the plug on the side of the tranny for the 350c version i am assuming it has been swapped.

You can't see the plug from the bottom. The plug faces up, not on the side. Yes could have been swapped.

 

[Ricko1966]

I read it could possibly be something with the electronic spark control? Does that sound right? I was going to run it with it off and then hook it up to see if it made a difference

The vacuum tip in switch looks similiar but deeper. Look at your distributor see if there is a 4 wire harness on it that goes through the firewall behind the glove box.if that harness is still there and plugged into the distributor you do have an ESC distributor,don't assume you still have one on a truck this old. Look and verify. I just looked at your firewall pic,that is a vacuum switch that unlocks the converter at low vacuum levels

 

[82goodlymadechevy]

Ok perfect no harness going into the glove box and I was wrong it has 4 speeds drive 1 2 3 but I do not see anything electrical on the tranny so im thinking im good thankyou guys for all the help this has been a work in progress to get it up to snuff the PO had wiring everywhere ready to chatch fire at any time a splice here a splice there oh what's these wire nuts doing here haha

 

[Ricko1966]

When it's time if you make your own lockup harness incorporate that vacuum valve it will unlock the converter when ever you are on the throttle hard,uphill,passing etc. If you don't find your factory wiring( and someone could have put a non lockup th350 in it in the past) if you do have a 700r4 and never find your factory wiring,we can walk you through wiring up the lockup.