Just got through checking out my front Diff. vacuum actuator. It's OK. Anyway, there is a "vacuum Tee" right before it goes to the acutator that has a stub on it with some sort of switch on the end. I think it is a switch because it has a wiring harness connected to it. My question.....What is this for? I've already determined through you guys that my problem with the actuaor not releasing after returning to 2HI is the vacuum switch on the xfer case.....thanks for that one.

Lynn Wagoner
Yukon, OK

Got me? Can you take a picture of it?

Believe you had the 3 buttom case so a 233 and if you mean on the transfer case 2 electrical things on it - the VSS or speed sensor and the 7 pin encoder motor connector. If you mean under hood then the T has a one way little plastic valve and then off to the Transfer and the plastic line to the heater controls.

Thanks for the reply, this thing is right by the battery....I will take a picture for you guys as soon as it warms up a little.

Under the battery tray is the font vac actuator - vac from the 3 port switch on 233 case is activated and that pulls a diaphram in that front actuator that in turn pulls the cable to the front axle coupler engaging the right side CV axle so now 4Hi (or 4Lo) can drive the front end. There is also a sensor with 2 wires on the front coupler to tell the TCCM its position.

OK, here is the picture. The switch in question is the one with the green connector. This vacuum stub goes to a "Tee", one leg to the xfer case vacuum switch and the other side to the vacuum actuator under the battery. Maybe a vacuum sensor for the 4WD computer???




http://img101.imageshack.us/img101/9027/vacuumyy9.th.jpg (http://img101.imageshack.us/my.php?image=vacuumyy9.jpg)