Engine/Transmission (1994 - 1998) '96 Auto Shift Problem

[charlessmith]

I've got a 96 2WD Ram 3500. This is a new acquisition, and it sometimes has a problem shifting from 2 to 3. The problem is very intermittent, usually only showing up after the truck has been sitting for a while. When it happens, I can sometimes drive a half mile in 2nd, getting to 2500 RPM under very light throttle with no upshift to 3rd. Eventually, when I lift clear off the throttle for 2 or 3 seconds it will decide to upshift. Once it's upshifted to 3rd the first time, it usually won't happen again for a while. Usually after the truck has been sitting for an hour or better.



Enterprise Engine in Thornville Ohio has been working on this, and the most recent step was to install a Goerend torque converter and valve body, which included new governor electronics. I'd wanted to do the TC and body change anyway. It has seemed to me that it might have been a shuttle valve sticking in the valve body or something.



After the change, the problem is still there. Their diagnosis says the throttle position sensor and other signal generators are operating correctly.



We are about down to the Powertrain Control Module. They believe the PCM can play with the governor control pressure to affect shifting like this.



Several questions -

* I also have a 97 Ram diesel automatic. Will the 96 and 97 PCMs interchange if I swap them to see if the problem moves (or goes away)?

The salvage yard interchange book says they are different ...

* Does anybody know where I can get a 96 Diesel Automatic PCM short of buying a new one from the dealer?

* Suggestions are very welcome!



Thanks.

 

[JFaughn]

I would think a good shop would use a professional scanner , monitor the system , also put some jumper wires at trans , so if while watching scanner to see if a signal is sent from computer , received at trans , narrowing down where the problem is , swapping parts is an indicator of the lack of diagnostic abilities .
It could be something as simple as a small piece of something in the trans keeping things from working right .
Then using use computers to test , is looking for trouble , no way to tell if your introducing new problems .
A 2nd tool of a good shop is using a scope for trouble shooting sensors , specially some thing like a speed sensor & throttle position sensor , some times very small glitches that only a fast tester like a scope will catch .

 

[charlessmith]

I think the problem is figured out. Not the PCM at all. Thanks to Dave Goerend for diagnistic help. I'll try to relate this so it makes sense ... The lip seal on the front clutch isn't always sealing, usually after sitting a bit. With a pressure gauge on some port, it was only reading 30 psi while exhibiting the "I don't want to shift to 3rd" problem, when shifting normally it should have been 100+ psi.

Thanks everybody for thinking about it. Enterprise was using a scanner, and was seeing a signal from the PCM saying "I want to be in 2nd". That was the thing that raised a question on the PCM. I apologize for giving everybody a Dick and Jane level description of this.

 

[BigPapa]

This is the same thing I was told on my '95 47RH. Here's the thread:



https://www.turbodieselregister.com...-95-auto-won-t-shift-up-into-second-gear.html



I didn't know if the leaking seal would matter on the 47RE so I didn't speak up. Good to know.



Scott

 

[WBerry]

96 auto shift problem

so are you replacing this seal?if so what are they charging to do this?is enterprise doing the job? i see you have a suncoastconvertor and v/b in 1 truck and gorendsbros t/v & v/b in the other. which works better?thanks. bill

 

[TBurow]

there is an updated seal which has a wider lip to seal a ridge that was not properly machined in the drum. i just rebuilt my 47re and the seal kit included both the old style seal and updated seal.

 

[Skydiver]

My 96 3500 did not want to shift when cold until I had the transmission power flushed which included running a preflush additive for 100 miles. Shifts on time now.

The transmission has 176k and still tows a 12k lb 5ver 6 times or around 1000k miles a year. I change out only the pan fluid about 5 qts. once a year. I always ease up on the pedal during TC lock-up.