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Virtual Wrench
Virtual Wrench, Master Mechanic
Category: GMC
Satisfied Customers: 14620
Experience:  Over 35 years experience on GMC vehicles.
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2003 s10 4x4. three lines come out of the vacuum switch but

Customer Question

Hi. 2003 s10 4x4. three lines come out of the vacuum switch but one has a "T" and one hose that T's off is not connected to anything. I pulled the hose off the Vacuum actuator and blew in it and air comes out of this hose that is just bobbed off and open. Is it suppose to be connected to something some place? My symptoms are the 4x4 wont engage because the vacuum actuator does not get enough pressure to pull the cable activating the diff. It gets some but not enough to pull the link.
Submitted: 1 year ago.
Category: GMC
Expert:  Virtual Wrench replied 1 year ago.


If you look at the diagram below it shows where that hose goes to. If i understand you it goes to a vent but not sure.

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Customer: replied 1 year ago.
I have the diagram. That is no help. What I learned, of all places is, that the T is where the transfer case vent and the main line vent come together. I tracked the vacuum back to the source, replaces all the lines, the vacuum switch on the trans, the vacuum actuator and the diff is not locking in even with the cable pulled tight. Is there a solenoid down in the diff that is related to the cable pull from the actuator? I'm convinced at this point it's not a vacuum problem. It's something in the diff. Any suggestions??
Expert:  Virtual Wrench replied 1 year ago.


There is a fork inside the axle housing that is related to the cable pull. It's what engages the axle. These break all the time. You are going to have to get in there to inspect it and i highly suspect that it is the fault.