My truck does not have a carrier bearing. The driveshaft comes out of the transfer case and goes into the rear diff so I am not sure about movement. I am going to pull my rear driveshaft out this weekend and check everything real good and if I do not find anything I'm going to put it in 4 wheel high and drive it without the rear driveshaft and see if anything changes. If I do not come up with something obvious I am going to take it in. I think it is something with the transmission control module not telling the system what and when to do it. I will keep you informed.

 

Ok, this weekend I put my truck on stands and spent hours looking under it. I checked engine mounts , trans mount. I pulled the driveshaft and checked the u-joints very closely. I checked numerous bolts for being tight and any play where it shouldn't be. I came up with nothing. I pulled a small boat yesterday and now noticed a patterned hesitation that makes the tach needle jump 100-200 rpm's. The engine will surge a little then drop back to normal. It does this in a very predictable pattern when the rpm's are between 1500 and 1800 or so. I am now thinking it is a throttle position sensor but I do not have a engine light on. I am going to price one today and I if is reasonable I am just going to change it and see what happens.

 

It's interesting, I'm now thinking, like you, that the 'shudder' may be engine driven. I actually hooked up my go pro on the crossbeam, looking at the carrier bearing and went for a little drive. Saw zero movement. Nada. That's not to say that there isn't a problem there, I just can't pick it up on the GoPro. I also can't find anything wrong with the u joints, the bearing, nothing. All seams nice and tight... ?

Going to be reaching out to the dealership this morning, and getting a definitive answer on why they said the drive shaft was bad...

Until then, I'm going to be looking into cleaning the TB, checking the MAF, and looking into the TPS as well. My tach has always kind of 'clicked' back and forth at certain RPM ranges. Usually by no more than 50 rpm or so, and I can't actually feel anything, but it could be an indicator of something else, you know?

 

I work for a Cat dealer and have numerous techs that have worked at truck dealerships and a few of them said to check the TB. It could have carbon built up and sticking at low acceleration or limited throttle. Going to check it this evening. I think we are getting close.

 

The throttle body cleaning will only help with the idle. Once the butterfly opens some (foot on the gas), a dirty throttle body has no impact on performance. Since these trucks have no idle control valve, they rely on the small gap between the butterfly and throttle body to control idle.

 

Any updates Hamrick? I haven't been able to put a lot of time on this, work has kept me pretty busy...

 

I pulled my throttle body off and cleaned it throughly with no change. I am going to take it in next week and see what they say.

 

Roger that, thanks for the update. Interestingly, I pulled my boat out this weekend. As such, I disable MDS and kept the truck in TOW mode. Not a hiccup. Really beginning to think I need a transmission relearn, or there's some other issue. Can't find anything to support a bad drive shaft. Still, the saga continues...

 

maybe a torque converter issue? Tow haul mode changes the shifting pattern so that may be related.

 

I had a friend hook his scanner up to my truck today and it has one code under the transmission. P1DB6-00 Vehicle Speed signal Performance. Not much out there on this code. I am reading everything from possibly the Speed Sensor to ABS to the TCM.