Engine/Transmission (1994 - 1998) Erratic Shifting

[PSInt]

I have a 96 4X4 Automatic. I overhauled the transmission and installed a Suncoast Converter, Valve Body, and HD Overhaul Kit. It shifted like a race car for about 6 months. When fuel prices went through the roof I parked it for a month or two. Finally I got used to the outrageous diesel fuel prices and dedcided to drive it for awhile. Now I have a problem of very erratic shifting. Sometimes it shifts just fine, and sometimes it won't shift from second to third unless I let up on the accelerator All other shifting is normal. There is no slipping at all. For awhile I thought maybe the trans temp was affecting it but the more I drive it I'm finding there doesn't seem to be a pattern. Just works when it wants to. I checked the throttle pressure cable, adjusted it like the factory manual specified. I thought it was fixed and after about 3 or 4 stops it went back to it's old ways, no 2-3 shift. I'm open to suggestions

 

[tp0d]

well, thats a tough one...



I would first say to check as many electrical connections as possible, clean with TV tuner cleaner, and clean the battery terminals with a wire brush. Check all grounds, and go over all the transmission connections realll close.



if you cant find a bad connection, its possible you may have an issue with the gov pressure sensor. was that part of the VB rebuild you did?



good luck



-j

 

[PSInt]

The valve body is a modified unit I bought from Suncoast. When the transmission was first built it worked GREAT ! Nice crisp shifts ! Even now, when it decides to shift right it feels good..... no slipping, leaps when it shifts. It's just that about 60% of the time the 2-3 shift won't happen unless I let up off the accelerator. It's sometimes worse during the first 15 minutes of operation, except sometimes it shifts normally cold, once or twice, then starts acting up. I can't establish a pattern... . Nothing makes sense

 

[JPittinger]

Clean the TPS (throttle position sensor). Or get rid of it like I did and replace it with an in-cab resistor (pot). Search for TPS and you'll be up all night. -JJ

 

[Howard Durand]

I don't think the TPS has anything to do with the 2-3 shifting but, this being a 96, I can't say for sure. I think it has the 47RE transmission and utilizes more electronic control than the 47H so checking all electrical cables and connections is a good idea.

Try adjusting the TV cable so that at full throttle, there is about 1/16" to 1/8" of travel left in the valve lever.

Has the throttle cable recall been done on this truck?

 

[PSInt]

Is the shifting controlled by the computer on this transmission ? I was under the impression that this was essentially a 727 with an overdrive.

The throttle cable was replaced prior to the recall (previous owner), however the recall has not been done. I was under the impression that the recall was only for the throttle cable. Does the recall also replace the throttle pressure cable to the transmission ???

 

[JPittinger]

47RH=hydraulic, 47RE=electric. I agree with Howard, don't know if the TPS controls the 2-3 shift either, but it sure is easy to find out. Got 5 min to spare? Pull 2 screws, flood with electric cleaner, reinstall, and let us know what happens.



Before I rebuilt my RH, I installed gauges on the test ports and ran them into the cab. You can see what the pressures in the valve body are upto at various throttle positions and in different gears. It became clear that my VB was worn (after 200k one of the slide valves was sticking) and I happily purchased a new one from Dave Goerend. If you really want to know what's going on, the test ports are there to help.

-JJ

 

[Joe G.]

If you really want to know what's going on, the test ports are there to help.

-JJ

AMEN!!! The shift points are controlled by governor pressure so you want to know what that is plus what the other test ports are telling you. This pressure is controlled by a solenoid on the 47RE.

 

[PSInt]

Making Progress (I Think)

Today I removed the TPS. I looked at my factory manual (Imagine that ) to see if there was anything special to watch for. The manual had an installation tip. Said something about TSP being spring loaded and had to be rotated during installation. Mine was not spring loaded, that is until I douched it liberally with electrical contact cleaner. Once all the goo was removed it would spring back like it was supposed to. Things were starting to fall into place . the manual said it had to be adjusted but I didn't see any adjustment to it (probably gas engines). Drove it to work tonight and it worked much better, although not completely flawless. 2-3 shift would hang, and after I made it shift once, it would operate normally until I would shut it down. After a restart it seemed to shift normally after the first time I forced it to shift by letting up on the accelerator. Still not completely fixed but making progress. Going to test the TPS tomorrow if I get time. I'm sure Chrysler is very proud of a TPS and I doubt if it's available in the aftermarket. Autozone didn't show it.

Updates coming as they happen

 

[Joe G.]

If the TPS is the problem you should be aware that the "official" adjustment procedure doesn't work. There have been quite a few threads on this forum about the TPS and how to set it up to adjust it properly. You may have to open it up to clean it properly. There are also some theads on how to replace it completely. Look up stuff by Howard Durand and ridesamule on the TPS.

 

[PSInt]

It's back on the truck now. I didn't see any easy to get it apart for cleaning. Do you have the combination ? I agree that would be best.

 

[Joe G.]

Not all that easy. Most who have done it used a dremel tool. Did you look at any of the threads about the TPS? One big problem is that if you do manage to get it to work the most adjustment will get it to barely work. The '96 seems to be the worse year for TPS problems.

 

[PSInt]

I think I must be living right (sure). I drove it home from work tonight..... Working like a new one !!! Let's hope it stays that way ! Even if it acts up again I know which direction to go. I didn't even have to drill it out (yet). Thanks to all who gave me the good advice

 

[PSInt]

I should have known

Well, it lasted a whole day. This time I drilled two holes in the back to give it a GOOD cleaning. Douched it out REALLY good, blew it dry... put it back on the truck and now not only is my 2-3 still hosed, it won't go into OD. Best deal I found on a new TSP is just over $200. at NAPA. Must be gold inside that little thing. Luckily I have another car to drive. :-laf It'll give me some time to shop for a better deal. Anybody have a good source ??

 

[Swamp Donkey]

Keep workin on this one PSInt..... I am having the same sort of issues! LOL

 

[Howard Durand]

I am still using the potentiometer replacement for my TPS which is designed after an experiment posted by Ridesamule.

I can see no reason to ever go back to the factory TPS. OD engagement is predictable for each setting of the pot and the only downside is loss of the kickdown feature and auto downshift under load. I solved that with a foot operated "dimmer" switch. The pot can be mounted inside the cab or under the hood. Inside is better for keeping things clean. Search for posts by Ridesamule and his experience with the pot. I believe his truck is a 96 as well.

 

[JPittinger]

I replaced with the pot too. 15$ for a nice 1-turn from mcmastercarr.com (my all time favorite misc parts website) mounted below and to the left of the steering wheel. I hardly ever mess with it since its set where I like it. Its also nice that the TC doesn't disengage everytime I let up on the go pedal.



Just for future reference, is sounds like the TPS is affecting the 2-3 shift on a 47RE?

 

[PSInt]

The TPS seems to be having quite an affect on my truck. The original problem was with 2-3 shift. Cleaned it externally and freed up the moving parts. Fixed my 2-3 shift for a day. Next day problem was back... . hanging in second until I let up on the fuel, then it shifts to third. Drilled 2 holes and sprayed out the inside and now the 2-3 problem is still there AND I have no overdrive. TPS from Dodge, $225. , NAPA $208. 00 and Cummins wants an engine S/N before they can tell me anything. I have a friend that used to work at a Dodge Dealership. He's going to see what he can get it for. May end up with a POT but I'm going to exhaust all the avenues first. What's all this talk about flashing it ? I'm having a hard time understanding why only my 2-3 shift is screwed up... and of course now the OD, but I induced that.

 

[Mr. Ken]

I think Rock Auto .com has em for about $160, ships very fast. When I was checking I was told they are all the same. Also I read in the TDR mag article, wrapping the wire from the Alternator can help too. maybe

 

[Howard Durand]

PSInt,

Before spending a bunch of money on a new TPS, check the one you have with an ohm meter to see if it is working at all then find out if the dealer can re-program your PCM.

Also, the 96 and later vehicles seem to be more susceptible to electrical noise getting into the TPS circuit. I think they use the same wire and voltage source for more sensors than just the TPS. According to my service manual, the 94 uses a dedicated 5 volt supply for the TPS.

The best cure for noise is to install a couple of filter capacitors. One between the signal wire and ground and another between the 5 volt wire and ground. These will smooth out spikes getting into the cable from other sources.



Assuming that everything was working properly before the transmission upgrades, the next consideration would be to make sure nothing is wrong inside the transmission. Both electrically and mechanically.