I have a '99 Ram 2500 24 valve Diesel. It seems for no apparent reason or tell-tale signs of trouble, my tranny decided to not up shift out of 1st unless I let off the gas pedal. The fluid is clean (changed filter & gasket last month). I read in this forum how some people have had problems and changed the VSS sensor. I did this but it did not change anything. No DTC codes, clean ground connections, even reset APPS without change. It just decided to do this this morning for no reason............ HELP.........is there any experienced proffesional trans techs out there that can give me technical assistance???? I am a master auto technician myself, but trannys is not one of my areas of expertise.

 

Mine did basically the same thing about a week ago.
But only on the 1st shift after a start-up.
A new Trans Speed Sensor (about $23.00 from my local auto parts store) cured my problem.
Look in my gallery for a picture of the sensor (located on the driver's side near the cross member) and the box with the part number.

https://www.dieseltruckresource.com/...29PICT0136.JPG

https://www.dieseltruckresource.com/...29PICT0134.JPG

Hope this helps

 

Mine also did the exact same thing,only on startup.
And I also just had to replace the speed sensor near the rear of the tranny for 23.99. It took about 2 minutes.

But I did run my scanner and there was a code...although the scanner called the faulty part a longer name than speed sensor.

 

The 99 trucks must be scanned to find any codes. Auto Zone does it for free.
It could be a sticking valve, but most likely is the gov. pressure sensor and or transducer. They are on the valvebody.

 

I found out what was the matter with my trans upshift problem. For those of you out there who have tried the Speed sensor, Governor soleniod & Transducer and it still did not work!!! Look for a busted front band strut. This is the part that the front band adjustment screw rest against inside the tranny. You can see the end of the adjustment screw it if you look up and around the valve body. you should be able to see the cast iron part twisted to one side, Thus no front band engagement. Unfortunately it's not a quick fix.

 

With the front band not working, it is skipping 2 nd gear and goint directly to third when you lift the throttle!!

 

I'll have to check that out, although I have the same problem my issue is 2nd to 3rd. Everytime I think I have it solved it comes back. New output shaft speed sensor, new gov pressure solenoid, new gov pressure sensor, new transmission relay, nothing has worked so far. I'm stumped, at least it is only an occasional issue though.

My dad had heard that maybe there is a new flash for the computer for early '99's? Mines was made in January of 99. I went to the dealer to inquire about it and the guy at the desk had no idea and his staff had already went home so no one else to ask at the time. Anyone heard of this?