Alaska; 86’ 4x4

[BJedi76]

Can anyone help me identify my 700r4 transmission?

I'm curious about the lock-up activation circuit.

The Canadian” 350 engine came out of a 80’ California, 1 ton van.

The carb didn’t come with this engine.

I’m just trying to get the best mpg possible.

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[BJedi76]

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I read a reply on another thread, about a circuit that originates from the vacuum thermal switch on the thermostat housing.

obviously mine is not even connected.

exactly how and where do I hook this up?

also: what is the other unit on the housing? it looks like a temp. sending unit.

...and what is the other switch on the “front passenger side” of the intake manifold? do i need it?

 

[1987 GMC Jimmy]

Is the truck a California emissions truck or a Canada truck? Does an orange SES light or a red Choke light come on when you first turn the key? The reason I ask is if it was a California truck, the ECM controls your TCC lockup. If not, the vacuum switch is supposed to be on the firewall. What you took a picture of is the EFE TVS that controls that flapper valve on the passenger side manifold. The other item in your thermostat housing is a broken CTS, as you suspected. There’s something else there, can’t tell if it’s a vacuum tree or some kind of thermal switch, but it’s not ringing any bells. The engine definitely looks like it came out of a model year 1981-86 truck or van. Does it have the electronic carb or did someone swap that out? If it’s not running a computer, you’ll need the vacuum switch to make the lockup circuit work. If we can establish your emissions setup (Canada, Cali, high altitude, or 49 State), that’s what you need to follow rather than trying to make the OBD I stuff on that engine work.

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[BJedi76]

The engine was replaced (not by me.

the engine # is K0320UFC

The carburetor is random too.
#17066559 M4MC

this truck is a Frankenstein...

The choke light doesn’t light up. It’s probably not connected to anything.

i have the vacuum switch on the firewall. i didn’t know what that is. lol. glad to know...

how do i connect it up properly?

 

[1987 GMC Jimmy]

Okay, so that other TVS could be for that. It’s not supposed to lock up until you’re at operating temp so there definitely needs to be a thermal control somewhere. It’ll derive vacuum from the carb and go to the TVS and then the switch. There’s also supposed to be a delay valve in the vacuum circuit. If yours is gone, you may have to improvise because I doubt they’re making those specific ones. If you’re able to pull all the stops on the vacuum stuff, all you gotta do is plug in the connector, and if your brake switch works, and the connector is plugged into the transmission, give it a try.

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