Greetings everyone. I usually read but this time I need some help. I've started to have shifting problems. I've got a 95, 3500 auto. The only mod is a #6 tst plate. From a standstill the truck will shift okay up thru 2nd. It would normally shift into 3rd at about 42,43 mph and then OD at about 55. Recently it started to have trouble going into 3rd. Road speed would go up to 55 and tach at about 2200 and it wouldnt shift. I discovered that if I let my foot off the pedale a little it would then shift and then go into OD normally. Playing with it I also discovered that if I let off the pedal a little at about 45 it would shift into 3rd. I have 110k on the truck and about 45k on this transmission. The dealer replaced the old one under waranty. Could this be a TPS problem? I did check the fluid which was clean and not burned and the level is good.
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Engine/Transmission (1994 - 1998) Transmission Problems
- Thread starter PKemp
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You might want to check the Throttle Valve cable that goes down to the trans from the injection pump. My cable was stuck at the full throttle position (rusted) giving high/hard shifts. The lever at the trans should move freely.
Joe
Joe
more info
Need to look at this a little closer. If your rpm is around 2200 at 55 then you may be IN third. That is about what my truck does. You may be confusing OD and lockup. A lot of the stock transmissions shift to second just after the wheels start to roll good and with the loose factory converter it almost isn't noticeable. Try it with OD cancelled. You should feel two shifts and then lockup. Mine ('98) with OD cancelled commands lockup around 35. With OD on, light throttle, OD is commanded RIGHT after the 2-3 shift and lockup is around 42 or so. If you are actually not getting OD or lockup then it could be a TPS problem.
Email me your phone number and I'll give you a call and see if I can help.
James
DTT installer/builder
Need to look at this a little closer. If your rpm is around 2200 at 55 then you may be IN third. That is about what my truck does. You may be confusing OD and lockup. A lot of the stock transmissions shift to second just after the wheels start to roll good and with the loose factory converter it almost isn't noticeable. Try it with OD cancelled. You should feel two shifts and then lockup. Mine ('98) with OD cancelled commands lockup around 35. With OD on, light throttle, OD is commanded RIGHT after the 2-3 shift and lockup is around 42 or so. If you are actually not getting OD or lockup then it could be a TPS problem.
Email me your phone number and I'll give you a call and see if I can help.
James
DTT installer/builder
Well, I didnt have much time to investigate but I did find a fairly straight stretch of road and from a dead stop, turned off the overdrive and stepped away like normal. With the OD off it seems to shift like it should. Minus the OD of course. It tops out at a little over 2k rpms and 55 mph. I turned around and tried it with the OD on and the problem pops back up.
I havent checked the throttle cable to make sure its adjusted right yet but i'll do that next. I'm borrowing a digital voltmeter tomorrow to check the tps voltage. I'll let you know asap.
Thanks for the help..... Pat
Pat,
Your '95 has a 47RH instead of the 47RE like the later ('96 and up) trucks. The main difference is the mechanical governor instead of an electronic like the later ones. Your problem may be related to pressure. You really need the service manual to do the tests right. The governor pressure should be about 1 PSI per MPH. For example 15 MPH should be about 15 PSI. The pressure should increase smoothly as the truck goes faster. If it does not then you may have a governor problem.
Line pressure for an unmodified 47RH should be about 60 PSI and increase to about 95 PSI with the transmission in gear and the transmission throttle lever moved from full forward to full rearward position.
The TPS does not get involved until the 3-4 shift and torque convertor lockup. The 2-3 shift is pressure controlled.
As Piersol mentioned, if the line pressure is lower than it should be the lip seal may be leaking.
Your '95 has a 47RH instead of the 47RE like the later ('96 and up) trucks. The main difference is the mechanical governor instead of an electronic like the later ones. Your problem may be related to pressure. You really need the service manual to do the tests right. The governor pressure should be about 1 PSI per MPH. For example 15 MPH should be about 15 PSI. The pressure should increase smoothly as the truck goes faster. If it does not then you may have a governor problem.
Line pressure for an unmodified 47RH should be about 60 PSI and increase to about 95 PSI with the transmission in gear and the transmission throttle lever moved from full forward to full rearward position.
The TPS does not get involved until the 3-4 shift and torque convertor lockup. The 2-3 shift is pressure controlled.
As Piersol mentioned, if the line pressure is lower than it should be the lip seal may be leaking.
Welll... The problem seems to be the 3 - 4 shift, not on the bottom end..... and then into overdrive. 3 to lockup doesnt want to work unless you let off the gas a little and then it shifts and overdrive follows. If you keep your foot in it you'll top out at 55 with no lockup and no OD. Let off the pedal and then it will shift.
???
Pat
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4th is OD. It should NOT lockup in 3rd unless OD is locked out. The shift sequence if OD is not locked out is 3 - 4 (OD), then TCC lockup. If OD is locked out then TCC lockup should occur about 35 to 40 or so. TCC lockup is alway supposed to be the last thing. If it shifts when the TCC is locked up the shift will be pretty hard. Try cleaning the TPS with some electronic contact cleaner and see if that helps. Just hose it down where the shaft comes out of the TPS and work the trottle back and forth.
I realize I'm having some problems distinguishing were this is happening so let me back up.
Its the last two "shifts". Which ones these are I'm not sure about the names. Its just that if you keep your foot down, like hitting an interstate on ramp and merging into traffic. It won't "shift" thru the last 2 points, it will just wind up to 2k rpms and about 55 mph and stay there unless you let off the pedal a little. Then it will "shift" and you can accelerate up to 78mph and 2200 rpms. Thats tops for this truck.
If you turn off the OD, It "shifts" very solidly up to 2k rpms and 55 mph just like a new trans. OD on feels "soft", OD off feels more solid.
I have cleaned out the TPS with gallons of QC spray contact cleaner with no improvement.
... ... . Pat
Its the last two "shifts". Which ones these are I'm not sure about the names. Its just that if you keep your foot down, like hitting an interstate on ramp and merging into traffic. It won't "shift" thru the last 2 points, it will just wind up to 2k rpms and about 55 mph and stay there unless you let off the pedal a little. Then it will "shift" and you can accelerate up to 78mph and 2200 rpms. Thats tops for this truck.
If you turn off the OD, It "shifts" very solidly up to 2k rpms and 55 mph just like a new trans. OD on feels "soft", OD off feels more solid.
I have cleaned out the TPS with gallons of QC spray contact cleaner with no improvement.
... ... . Pat
Just to get clear about what should be happening. These transmissions are three speed with OD acting as 4th. If OD is off, the shift sequence will be 1-2 2-3 lockup. If OD is on, 1-2 2-3 3-OD lockup. Lockup has a softer feel than any of the shifts.
Your top RPM seems to be a little low too. When mine was stock it would get to 2800 before the governor defueled.
Since you seem to be able to get it to shift if you lift, you might try to adjust the kick down cable. At full throttle there should be about 1/8" movement left before the throttle lever on the transmission hits the stop.
The adjustment is simple but hard to understand from reading the instructions. You need a small C-clamp to hold the button so you can move the adjustment easy. The kick down cable is the one with the pointed end near the bottom of the shift linkage. There is a cube looking part where it goes thru the mounting bracket. On the back of the cube is a bulge. This is NOT the button. It contains the spring for the button which is the flat side on the other side of the cube. Press and hold the button with the C-clamp so you can make the adjustment.
Your top RPM seems to be a little low too. When mine was stock it would get to 2800 before the governor defueled.
Since you seem to be able to get it to shift if you lift, you might try to adjust the kick down cable. At full throttle there should be about 1/8" movement left before the throttle lever on the transmission hits the stop.
The adjustment is simple but hard to understand from reading the instructions. You need a small C-clamp to hold the button so you can move the adjustment easy. The kick down cable is the one with the pointed end near the bottom of the shift linkage. There is a cube looking part where it goes thru the mounting bracket. On the back of the cube is a bulge. This is NOT the button. It contains the spring for the button which is the flat side on the other side of the cube. Press and hold the button with the C-clamp so you can make the adjustment.
Well Ive had a chance to check the throttle cable adjustment and the TPS voltage so far.
I have the new throttle cable assembly (recall) installed. Its right at 5" at the idle position. I believe thats what its supposed to be.
I checked the tps supply voltage and it is 5 volts. The voltage at idle position was . 486 volts. I did the "oval out the holes" trick and managed to get . 821 volts and no more. I had someone slowly step on the throttle and it went smoothly up to 3. 02 volts with no spikes or jumps. Couldn't get any more out of it. I cleaned it up and took it back out on the road. Absolutely no change at all. Could it be because of the low TPS voltage?
Alas and Alack... . I am lost... I should get a chance to check your transmission "button" suggestion this weekend. There are no apparant leaks in the trans. The filter and fluids were changed about 8k miles ago. It looks and smells clean. The dealer replaced all the transmission lines with the solid screw in type months ago.
P. S. What is and where is the "lip seal"????
I have the new throttle cable assembly (recall) installed. Its right at 5" at the idle position. I believe thats what its supposed to be.
I checked the tps supply voltage and it is 5 volts. The voltage at idle position was . 486 volts. I did the "oval out the holes" trick and managed to get . 821 volts and no more. I had someone slowly step on the throttle and it went smoothly up to 3. 02 volts with no spikes or jumps. Couldn't get any more out of it. I cleaned it up and took it back out on the road. Absolutely no change at all. Could it be because of the low TPS voltage?
Alas and Alack... . I am lost... I should get a chance to check your transmission "button" suggestion this weekend. There are no apparant leaks in the trans. The filter and fluids were changed about 8k miles ago. It looks and smells clean. The dealer replaced all the transmission lines with the solid screw in type months ago.
P. S. What is and where is the "lip seal"????
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If the kick down cable adjustment doesn't fix it, then I think you have a pressure problem. If you do then the transmission is wearing out.
The front clutch pack has a piston inside of it to apply the clutches. The seal around the piston is called a lip seal. The original type of lip seal is prone to leaking. There is a replacement for it that has more "lip" and is not as likely to leak. If the lip seal leaks it causes a drop in pressure Then there is not enough pressure to apply the clutches properly and they wear. Replacing the lip seal requires a transmission tear down. Might as well overhaul it if that is necessary.
If adjustments don't fix your problem then you will need an overhaul before too much longer. A pressure check will let you know if your pressure is lower than it should be.
Since you need to lift to get it to shift properly I suspect low pressure. That was the first symptom I had with the stock transmission when I had problems with it.
The front clutch pack has a piston inside of it to apply the clutches. The seal around the piston is called a lip seal. The original type of lip seal is prone to leaking. There is a replacement for it that has more "lip" and is not as likely to leak. If the lip seal leaks it causes a drop in pressure Then there is not enough pressure to apply the clutches properly and they wear. Replacing the lip seal requires a transmission tear down. Might as well overhaul it if that is necessary.
If adjustments don't fix your problem then you will need an overhaul before too much longer. A pressure check will let you know if your pressure is lower than it should be.
Since you need to lift to get it to shift properly I suspect low pressure. That was the first symptom I had with the stock transmission when I had problems with it.
PatI don't think you are in danger of walking any time soon, but if the pressure is low it's just a matter of time.
There is some risk here of starting a transmission war, but I like DTT. Their web site is: http://www.dieseltrans.com/
There is some risk here of starting a transmission war, but I like DTT. Their web site is: http://www.dieseltrans.com/
I don't know if this has any bearing on your case but I recently checked the 5" dimension specified by the manual for the throttle cable setting.
The cable had been replaced under recall and I wasn't satisfied with the way the transmission was acting. I found the measurement to be about 1/4" off.
I adjusted it to the proper dimension and took it on a test drive.
It didn't seem to make any difference.
Later, I unplugged the main cable connector to the PCM to check the wiring for another project I have in mind.
After I replaced it, the transmission started shifting more like it should have been doing.
I don't know for sure if unplugging the PCM reset the computer so that it recognized the change or if it just makes better contact now.
The low voltage readings you are getting from the TPS makes me wonder about some resistance in the connections.
By the way, that 5" dimension is measured laterallly between the face of the bracket and a vertical line which passes through the center of the pin. I think the dealer just measured point to point between the bracket and the pin.
The cable had been replaced under recall and I wasn't satisfied with the way the transmission was acting. I found the measurement to be about 1/4" off.
I adjusted it to the proper dimension and took it on a test drive.
It didn't seem to make any difference.
Later, I unplugged the main cable connector to the PCM to check the wiring for another project I have in mind.
After I replaced it, the transmission started shifting more like it should have been doing.
I don't know for sure if unplugging the PCM reset the computer so that it recognized the change or if it just makes better contact now.
The low voltage readings you are getting from the TPS makes me wonder about some resistance in the connections.
By the way, that 5" dimension is measured laterallly between the face of the bracket and a vertical line which passes through the center of the pin. I think the dealer just measured point to point between the bracket and the pin.
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Howard..... I did check between the outside of the flat and the center of the ball for the 5" just like it says in the procedure and if its not exactly 5" its darn close so I can't see the diff.
I will check the PCM connector if I can find it.
Joe... . I will look into those trannys also, thanks... these dodge trannys are a real problem. I have a friend who has given up on them also and is looking for a new heavy duty trans. Hes on his 4th in 117k miles.
..... Pat
I will check the PCM connector if I can find it.
Joe... . I will look into those trannys also, thanks... these dodge trannys are a real problem. I have a friend who has given up on them also and is looking for a new heavy duty trans. Hes on his 4th in 117k miles.
..... Pat
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could it be that you need to take the tps wires out of the harness and put them into their own loom?... ... it fixed my problem.....
https://www.turbodieselregister.com/forums/showthread.php?threadid=50793&highlight=tps
https://www.turbodieselregister.com/forums/showthread.php?threadid=50793&highlight=tps
That reading of 0. 486 volts on the TPS at idle position doesn't sound very good. It should be between 0. 8 and 1. 2
Mine reads 0. 82 and works fine.
The question is, why didn't anything change after you were able to get it up to 0. 821?
It appears you have a pretty good voltmeter to be able to get a reading to three decimal points.
Since you are getting a good reading on the 5 volt signal I wouldn't think a digital voltmeter would make it any better.
If you could monitor the TPS voltages while the engine is running you might be able to see if electrical noise is getting into the circuit which could make operation erratic.
If that is the case it can be cured by connecting a 400 microfarad, 35 volt electrolytic capacitor between the signal wire and the ground wire as close to the PCM as possible.
As I said before, changes I made didn't have any effect until I unplugged the PCM then plugged it back in.
If all that did was reset the PCM, you could do the same thing by disconnecting the batteries for a minute or so.
On the other hand, even though the PCM plug and socket appear to be quite high quality it is possible for the anti corrosion grease to dry out in time and if any corrosion did occur, poor contact could cause a loss of voltage. Moving the plug out and back in should reestablish good contact.
The PCM connector is fairly large (about 60 wires going to it) and is on the passenger side firewall behind the air cleaner. One hex head bolt holds it in place.
Just to be safe, you should probably disconnect the batteries before unplugging the PCM. I didn't but probably should have.
Pull and wiggle the connector as you loosen the bolt until it comes out.
I didn't try to clean mine when I got it out, I just shoved it back in and tightened up the bolt.
I apologise for my long winded reply. Hope it helps.
Howard
Mine reads 0. 82 and works fine.
The question is, why didn't anything change after you were able to get it up to 0. 821?
It appears you have a pretty good voltmeter to be able to get a reading to three decimal points.
Since you are getting a good reading on the 5 volt signal I wouldn't think a digital voltmeter would make it any better.
If you could monitor the TPS voltages while the engine is running you might be able to see if electrical noise is getting into the circuit which could make operation erratic.
If that is the case it can be cured by connecting a 400 microfarad, 35 volt electrolytic capacitor between the signal wire and the ground wire as close to the PCM as possible.
As I said before, changes I made didn't have any effect until I unplugged the PCM then plugged it back in.
If all that did was reset the PCM, you could do the same thing by disconnecting the batteries for a minute or so.
On the other hand, even though the PCM plug and socket appear to be quite high quality it is possible for the anti corrosion grease to dry out in time and if any corrosion did occur, poor contact could cause a loss of voltage. Moving the plug out and back in should reestablish good contact.
The PCM connector is fairly large (about 60 wires going to it) and is on the passenger side firewall behind the air cleaner. One hex head bolt holds it in place.
Just to be safe, you should probably disconnect the batteries before unplugging the PCM. I didn't but probably should have.
Pull and wiggle the connector as you loosen the bolt until it comes out.
I didn't try to clean mine when I got it out, I just shoved it back in and tightened up the bolt.
I apologise for my long winded reply. Hope it helps.
Howard
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I did pull the TPS wires out of the loom and put them into their own like previous Posts had suggested and that didnt change anything either. But the voltage is low. I do have a really good digital voltmeter. I'll see if I can find some wires long enough to run it into the cab so We can see what its doing while driving. Im also looking for another TPS, my dealer doesnt have any but can order one for $220. 00 "pay up front before ordering!!!!!" Ye-gads!!!!
I couldn't find a transmission service/repair manual for a 47RH anywhere, even the dealer didn't have one, so I ordered one from ATGS. Its gonna be a few days before I can do the pressure checks and linkage adjustment checks. I have found some high pressure hose and a gauge though so I can bring it in the cab to see what its doing while driving.
This is turning into an over-the-road experimental test bed here. All the better if it helps someone else later. I'm keeping track of everything, and writing it down so I can give you'all a good report when this is done.
Ill holler as soon as I have something new to report... . Thanks Everyone... ...
I couldn't find a transmission service/repair manual for a 47RH anywhere, even the dealer didn't have one, so I ordered one from ATGS. Its gonna be a few days before I can do the pressure checks and linkage adjustment checks. I have found some high pressure hose and a gauge though so I can bring it in the cab to see what its doing while driving.
This is turning into an over-the-road experimental test bed here. All the better if it helps someone else later. I'm keeping track of everything, and writing it down so I can give you'all a good report when this is done.
Ill holler as soon as I have something new to report... . Thanks Everyone... ...
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Issue 128 – Digital Version
Digital Magazines
FREE!
TDR Test Drive - Digital Edition
Renew
Subscribe
Gift Subscriptions
Back Issues
Subscription Status
Address Change Form
Buyer's Guides
Ram Diagnostic Trouble Codes
The Perfect Collection
The Perfect Collection Vol. II
TSB Updates
Dodge/Cummins Historical Overview
Cameron Collection
What Makes Us Tick?
Product Showcase
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