Guess that part!
 

Better yet tell me what it is...

Also, where does the black connector go?

Re: Guess that part!
 

What is it?

Re: Guess that part!
 

That 4 prong plug looks the one that goes down to the drivers side of the transmission for torque converter lockup.

The black plug looks like an oil pressure sensor connector.

Re: Guess that part!
 

Yes. First pic is for trans harness. The white does go to the trans, the red is a "test" connector. The black I don't believe goes to oil sender. I think the oil sender connector is a single prong.

Re: Guess that part!
 

I still would like to know what the vac switch on the firewall is for. There is another that I'm doing away with that is part of the ESC system.

Re: Guess that part!
 

The black [round connector] looks like the oil pressure SWITCH that is on the block (drivers side)-not to be confused with the oil pressure sender/switch for the guages/idiot light. Used for the power feed to the electric choke, no oil pressure, choke won't get 12v, once oil pressure achieved, switch closes sending 12volt to the choke, it is also what triggers the CHOKE light.

The bottom vacuum device is for the transmission, overdrive, forget what it exactly does, might be over drive override, or overdrive cancel. If you got a factory wiring diagram with the separate transmission callouts, you'll locate it quickly.

Alex.

Re: Guess that part!
 

To me the black plug looks like it goes to the low pressure switch for the A/C

Re: Guess that part!
 

Vacuum Switch for the torque converter lockup inhibit.

The white 4 position square Weatherpack is usually an early TH700R4 or TH350C lockup control harness connector.

A few WAGS on the black plug... Not knowing the (*&#%$^( model year makes these more than a challenge.
If the wires in and out of the round black plug are GREEN then it's the LPCO for AC. If they are BLUE then it's the Oil pressure switch just above the oil filter for the CHOKE. The ESC system uses a round black plug to the Knock Sensor on the oil pan rail next to the LH motor mount.

It's kind of a (*&^%() to figure out what these are when we don't know what year the truck is... Just put it in your signature if you don't like typing it over and over.

Re: Guess that part!
 

Sorry! It's a 1986 w/ TH350C. I believe the oil press switch is correct. The vac switch on the firewall hasn't ever had a vac hose connected. Would that be fed from full man. or ported? Do I even need it?

Re: Guess that part!
 

He is right.