When I push four low button I can hear the transfer case motor working but the hubs don't lock in (they don't lock in four high either). I have learned that there is a vacuum operated switch on the transmission or transfer case that operates the hubs. Can anyone tell me where that switch is located and if I'm on the right track or not? Should I be more focused on the hubs themselves? Any help would be appreciated.

 

If its a s-10 check the tcase switch and the vac actuator for the front diff, I dont think we can do anything with our "hubs" but replace them when they go bad.

 

the vac actuator should be under the battery tray.

 

And the transfer case switch is on the sdriver side top of the transfer case closest to the frame, you get like 2" of wrench swing room so I hope you have some patience.

 

I aagree, if it's an s-10, it's got full time hubs so to speak. If your lights on the dash mounted switch are lighting up when you press 4hi or 4lo, then I probally would think it's the front axle vacumn actuator located under the battery.

 

thanks for the info, the lights do light up on ;the switch and you can hear a clunk when four low engages so I know the transfer case motor is doing its job so i will start w/ the vacuum actuator under the battery.

thanks again, I will post my success or lack of.

 

Easiest way to tell. Put it in 4lo. Put the truck in park. Reach under and grap the front dirveshaft. If you can turn it, your t-case didn't lock in. I you cannt turn it then the problem most liekly lies in the vacuum system. There is a vacuum switch on the t-case (location given in above post). There are three hoses. One provides vacuum, one is a vent, and one runs up to the vacuum actuator under the battery tray. To test the actuator, disconnect the vacuum line, push the diaphram in with your finger, place your thumb over the vacuum line hose fitting and let the diaphrame go. If the diaphrame moves, the actualtor has a leak and needs to be repalced. If the actuator holds pressure, then you have either a vacuum leak in one of the hoses (supply to t-case, or supply to actuator). Or the cable from teh actuator to the front diff is stuck.

 

I pulled the actuator. It does have a leak and it also had some redish brownish liquid in it. My initial thought was tranny fluid but it didn't smell like it and it was much browner than dex III. I am now on the hunt for this actuator.

 

There is a small tear in the vacuum actuator, so that needs replaced. The fluid that was in it apparently was tranny fluid which in turn means that the transfer case vacuum switch is leaking which also needs to be replaced. The local gm dealer wants $98.00 for the actuator. I found some on ebay for 56.00 w/shipping. I got the transfer case switch for 14.00. So I am asuming that once both are replaced my problem will be solved.


Thanks to all of you who pointed me in the right direction. Hope I can return the favor sometime.

 

Maybe, you need to pull the fill plug on your t-case. If it guises tranny fluid you ahve a leaking front t-case seal. you will have to drop the t-case out to replace the seal. $5 part. Get some RTV and make a new gasket betweent eh adapter and t-case.

I would also check the vacuum line going into the cab of the truck. Look for the hose aroudn the center of the firewall, cheat towards the drivers side some. It runs to a tee right behind the distriburator. The vacuum comes off teh back of the intake by the distriburaotr, feeds that tee, which then feeds the t-case and HVAC system. If you ahve fluid in the vacuum line, then you more then likley have fludi in hte HVAC sysem. Hopefully, the fluid is only in the vaccum line to the actuator. But you have to check.