I have a 96 Dodge Diesel 4x4 and it is speratically NOT shifting in to overdrive. This is what I've done so far.
New: Main computer
Cylinoid
Transducer

And still the problem cont. It will shift fine then just when you think you've fixed it it does it again. I've had 3 different places put it on the scope and they all say it's not the transmission but no one seems to be able to pin point the problem. I've spent a small fortune so far in the last 6 weeks and need any help anyone can give me. When it is not shifting it is real sluggish from a stop and the RPM's will be 2,000 @ 45-50 MPH.
So please if anyone can HELP HELP HELP me I would appreciate it.

 

hello, first things first i wopuld start with a tps. especially since you have rulled out the computer. buy an oem one form cummins or borg warner aftermarket has the factory one in the box. sometimes they are a little cheaper, but not much. hope this helps.

 

Try using the search function and look for threads on the TPS (throttle position sensor). I think you will find all of the information you are looking for. It has been discussed many, many times so there is alot of good information available.

 

....not only TPS, but there are servicable bushings in the linkage where the TPS mounts. I often find on the older units that even after shop A installs the TPS it can vary up to .5 volt due to play in the shaft.

 

Thanks to everyone for their advise I am going to try a TPS and will let you know how it goes. This Forum is Extremely helpful.

 

Pretty expensive "diag-throw-sis". You could round up a scanner or use a dvom to see what it's voltage reading is at idle. .85 to 1.0 usually gets the job done.

 

If it's extremely sluggish from a stop and won't shift into OD I'd do the following:
Get it scanned for a limp mode condition- if the PCM sees something out of whack it will try to protect the tranny by starting out in 2nd gear or even 3rd gear.
Maybe it's just that your line pressure has been increased (shift kit or the like) and you need a resistor.
The TPS is also a possible culprit.
To rule out any internal problem with the OD unit you can install 2 manual switches to activate OD manually and to apply lockup. (Installation instructions are on this site somewhere)
I hope you get it sorted out..

AlpineRAM

 

Alpine - I thought the '96 trucks did not have a "limp" mode (but I could be wrong - I have a '95). As stated the TPS is pretty expensive so that is why I suggested a search of the existing threads. There is already a lot of information available here that will help to diagnose the problem if it is the TPS.

Also if it is real sluggish from a stop you could try manually moving the shift lever to 1st to see if it will downshift. This could be a problem with the adjustment of the throttle valve cable.

 

Sidewinder has a point, I watched a friend of mine on his 96 go nuts before he looked at the tvcable. After he adjusted that his problems were cured.

 

I have the 91 and the 97. The 97 manual says coolant temperature sensor can prevent 3-4 shift as well as TPS. There are a bunch of other possibilities internal to valve body that are listed in the manual. One way you can eliminate these is by grounding overdrive solenoid (computer side isolated, check on this to be sure, I am going by memory) with a seperate toggle switch "jury-rigged" once you are up to speed in 3rd gear. This forces a OD shift regardless of sensors, as long as 3rd gear achieved. I believe the valve body prevents the OD shift unless it knows you are in 3rd gear in the 727 front portion of the tranny. The OD unit is on the tailshaft as an afterthought.

 

thanks for all the help!!!!!!!! Replaced the TPS and so far for two weeks has been running like a champ. You guys have saved my *#% again!!!