Hey guys new to the forum. I have a 99 old bravada and as usual it has AWD problems. I picked it up on a great deal from my bosses parents for 3500$ immaculate condition with only 80,000 miles on it. Unfortunately, I am having issues now. Under acceleration there is a clunking like a CV joint is binding. It got worse when I recently replace a front tire. I am a capable mechanic, in fact I repair heavy equipment for a living, but I cannot seem to find a definitive answer as to the cause of the problem, nor a definitive answer on how to disable the AWD so this does not happen again. I live in sunny california and have absolutely no use for the AWD.
I posted this in the new members section also so I apologize to the moderators for cross posting. Also, I was unsure if this belonged in drivetrain, or transmission section.

 

Noise from a CV is typically noticed when turning and usually starts off as a heavy clicking that is heard rather than felt.

The front driveshaft can cause a clunking sound when the joints go bad. If you crawl under the truck with it parked and try to move the driveshaft, there should be no play in it. If there is play in the front, you can put a new u-joint in it. If it has play in the CV style joint in the back, the shaft will need to be replaced. Typical wear is on the rear CV style joint.

To disable the front axle, you can remove the front driveshaft. The trick though is keeping the fluid in the transfer case as the seal is to the yoke portion of the front driveshaft. It has been a long time since I have had one apart, but if there is a snap-ring on the stub shaft out of the front of the transfer case, then you could try disassembling the rearmost yoke from the front driveshaft and then installing it into the transfer case.

As far as the other post goes, please post a new introduction thread. You can even link to this thread for more exposure, but we like to keep tech questions in the appropriate sections and out of the introductions section. This section is actually where I had thought to move your other post to, but saw this post prior to making that move.

 

swartllk,
I had read somewhere to not pull the front driveline as the transfer case is a split power case? so if i pull the front drive line I will eventually lose power to the rear as well. My initial reaction was to pull the front driveline also, but after seeing that I was worried. My plan today is to manually shift it to put it up on the lift at work and manually shift it out of awd and then disconnect the encoder motors from the TC and front diff, but I read this will cause the AWD light to be on which will probably drive my wife insane.

 

Prior to 1998, the transfer case was a dedicated torque split and removing the front driveshaft would cause damage to the clutch pack. The NV236 transfer case uses a preloaded clutch pack on the front output which causes the front output to spin all of the time, but retains a solid link between the transmission output and the rear axle output. Removal of the front driveshaft, while not ideal as designed, should cause no adverse effects on the transfer case.

Look at it this way, the NV236 (2 speed, auto4wd transfer case found in other s-series trucks) has the same front axle output configuration, but runs around in 2wd with the front axle itself disconnected internally.

Unless there is a problem somewhere, the transfer case is always in 2wd (or as close as it can get) unless slip is detected in the rear wheels. Disconnecting the shift motor will cause a 'service awd' light on the dash as you mentioned.

Regardless, if the problem is with the front driveshaft, defeating the awd by any other means other than pulling/replacing the front driveshaft itself would not remedy the clunk you are experiencing. If replacing the front driveshaft is economically feasible, that would produce the least amount of side effects for sure.

 

fantastic information, thank you. I intend for this to be a temporary solution, but in the long run I wish to convert it to push button 4wd with a tc from an s10/blazer, have you seen this done and if it has been done here can you shoot me the link, I looked but there are so many results from search engines now days, it is hard to find what you are looking for.

 

It would be much easier from a feasibility standpoint to change over to the manual shift transfer case (NV231). This was still offered in some 2nd gen S-series trucks, but is somewhat rare.

Regardless of the 2-speed selectable transfer case chosen, I cannot think of any way around reprogramming things in the truck to account for the lack of certain inputs and the presence of new inputs if you were to go to a push button transfer case. There are certain things that happen with the NV233 & NV236 that are different than the NV136.

For example, with the 2-speed selectable transfer cases, when in 4LO, a circuit is completed telling the PCM that 4LO is selected, allowing it to change up the transmission shift schedules due to the gearing change. I am not sure if this logic is there in a PCM from a vehicle equipped with the NV136 transfer case.

Wiring will likely be different as well.

 

understood, but if I use a manual t-case, it wont have that option

ok some quick questions, on the s10 t-case, is there 1 decoder motor or 2?
and, is there a single sensor for each motor, or multiple?

the reason I ask is, (and not trying to toot my horn) I'm a bit of an electrical guru, and I'm thinking, I could controll all 3 functions of an electric t-case using the switches, and 3 2 way relays, which are available at autozone for about 8$ each

BTW, I was able to pull my front drive shaft with no issues, t-case has a male spline sticking out, which appears to have a seal around it. drive shaft does not seal inside the tranny like on the rear where the yoke goes inside of a rubber seal.

 

ok, so it looks like 1 decoder motor, so there must be 3 sensors, 2wd,4wd,and 4L i wonder if could use a reversing switch, and then indicator lights hooked to the sensors to tell me when I am in a specific range/gear