Vacuum Port?

Does anyone know what this port is supposed to be used for?

 

Hm...interesting. my 02 doesn't have that? Is that from a 96-00 model?

 

01

 

I will take a guess this motor probably came from a different vehicle,

 

That would be the source point for a vacuum ADD actuator.

 

Don’t think so.

The what what? lol What is an ADD actuator?

 

It has something to do with my front differential I’m guessing? It was capped off when I bought the truck a few months ago. It’s a 2001 4wd.

 

Automatic Differential Disconnect system, in place of manual locking wheel hubs. You can google it. It essentially allows the front axles/spider and side gears to spin (with the front wheels in 2wd) without spinning or connected to the ring/pinion gears and front drive shaft. When the transfer case is shifted into 4wd the ADD system is "actuated" allowing power transmission to the front wheels. It takes the place of conventional manual (disconnecting) hubs.

Earlier trucks had vacuum powered ADD actuators, later were electric.

Does 4wd work?

 

Thanks. I’ve been doing some googling. I don’t see the large actuator I’ve seen in some pics. 4wd does work.

 

I’m having a pita idle problem and I’ve found zero vacuum leaks and I’ve replaced the iac, tps, and cleaned the throttle body. Saw this little port and wanted to know what it was. No luck with the idle btw.

 

Make sense, I recall reading that the ADD system uses vacuum to lock/unlock.

 

The front diff must have an actuator located on the pass side of the front diff facing the rear. If not and 4wd works then some modification has been done such as swapping in a manual hub differential.

Vacuum actuator. Looking forward, over and beyond the steering rack. Has 2 vacuum lines and a switch to illuminate the dashboard 4wd light.

 

Here is what mine looks like

 

That is an electric ADD actuator. The hose is simply a vent.
The factory swap to electric was right around your year. Forget about the capped off port and move on with life.

 

Perfect. Thanks! Moving on!