Ok so to start out my truck is a 2000 Oldsmobile Bravada with the NV136 (I think) fully automatic transfer case. It doesn't have 4LO. Well my 4wd hasn't worked for almost a year and has been STUCK in 2wd for just as long and a few days ago I decided to go through a car wash (Which I hadn't been through for about a year as well because of lights mounted on roof) to clean off the salt from the roads and after coming out of the carwash I pulled to the end of their driveway to pull onto the street and then peeled out onto the street. When I did this I felt it try to shift into 4wd and then it started making a loud clunking sound like it was only half engaged and the teeth on the gears were "slipping?" Can anyone else give me insight as to what my problem might be? Could the underbody flush from the car wash caused something to work for a few seconds? If so Does that mean it would be a wiring problem? I have searched and found basically nothing. AND YES I KNOW HOW TO SEARCH!

 

Ok so I lifted my truck off of all 4 wheels and then started it up and put it in drive to see what would happen. Well my truck shifted into 4wd and the front driveshaft was spinning but my axle wasn't and there was no clunking sounds so I figure that means it has something to do with my axle spinning on its own. On olds bravada's the front axle is always engaged and doesn't have a vacuum switch under the battery tray or have a cable running to the front axle. My right front tire will spin but will resist and it is easy to spin for about 3/4 of the way around and then it is stiff and I have to put almost all my body weight into it to get it to spin past that stiff section and I weigh 180lb. My drivers side wheel will spin completely freely and it shouldn't because my front axle is engaged full time. When an axle is engaged and you spin one tire in the forward direction then the other tire will spin in the reverse or opposite direction. Can someone please help me out?

 

well first thing is to look at front axle on the pass. side and see if theres a actuator or not, will have a cable going to a extension housing on the front axle below the oil pan. as for the water, its got to be the tccm. take the pass side kick panel off, look for a metal box with a orange plug its right behind the panel. if u see rust anywhere of anysort u are in the rigth area. at your own risk remove and unplug look for bad pins and corrosion very common for water to find its way in here. ull need to clean or replace pins in plug or module may need to be replaced. either a yard or dorman products makes them new, look into tccm for blazers and dorman products on you tube they have a video up on the whole process. if you need furthur info there is a diy section with swartwikk's awesome breakdown on this entire system including the tccm.

 

My system Is A LOT more simple than the 3 button or 4 button on the jimmy or blazers. My truck has NO cable or actuator for the front axle because on 98 - 01 Oldsmobile Bravada's with the SmartTrak have full time engaged front axles so the front axle is always engaged. I lifted my truck off of all 4 tires and the transfer case is engaged and front drive shaft is spinning so it has to be something with my front axle/differential. What does the front drive shaft connect to on/in the differential?