Engine/Transmission (1994 - 1998) No shift

[Learpilot]

Lately, when my truck is cold, it does not want to shift from 2nd to 3rd gear. It seams that I had this problem a long time ago while still under warranty and the dealer replaced the torque converter. Has anyone experienced this problem? Is a failure imminent?

 

[SFPADGETT]

There is a temp sensor in the pan, and will not allow upshifts till it warms up, but ususally only the 3-4 lock up . Old fluid seems to make it worse, we change spring/fall (about 20,000 miles) on our service trucks. Welcome to TDR

 

[CBrabec]

is there anyway to bypass the temp sensor to fool it to think its up to operating temp even though its cold out? My truck has been doing the delay shifting this winter and is a PITA at times, espically when I let the truck warm up for 10 minuets or so and get on the freeway and the truck won't shift into over drive until the truck is at full operating temp.

 

[SFPADGETT]

You can, but I don't recommend it. It is there for a reason, which is to delay the shift until the transmission is up to temp, to "help" keep from causing damage to the transmission. I would first clean the contacts (wires) on the sensor plug in harness and see if that helps. You can look in the FSM (factory service manual) for the location and ohm rating of the swith, if you choose to bypass it. Being delayed a few minutes is WAY cheaper than replacing the transmission.

Remember that the diesel will warm up faster when under load and moving, not so much when parked and at idle.

 

[cerberusiam]

The 1-2 and 2-3 shifts are not influenced or controlled by the temp sensor. Its all hydraulic until OD is in play. Slow shifts cold are usually band adjustment and\or gov solenoid/transducer issues. Check the band adjustments first then think about the internal parts if the trans is an RE.

IIRC, the temp sensor can just be bypassed with a jumper wire so it reads good all the time. Will somewhat depend on year but pretty sure all the 12V stuff is the same, just a minimal reading needed for OD.

 

[CBrabec]

IIRC, the temp sensor can just be bypassed with a jumper wire so it reads good all the time. Will somewhat depend on year but pretty sure all the 12V stuff is the same, just a minimal reading needed for OD.

Which of the wires do I splice into to jump it? Also would a 1 amp OHM be enough to tie into for the power source.

 

[cerberusiam]

Which of the wires do I splice into to jump it? Also would a 1 amp OHM be enough to tie into for the power source.

I think if you just unplug the harness and make up a jumper wire with spade or round ends that fit th eplug you should be fine. I think those are a 5 volt minimal amperage circuit and the sensor is either open or closed.

 

[cerberusiam]

Which of the wires do I splice into to jump it? Also would a 1 amp OHM be enough to tie into for the power source.

I think if you just unplug the harness and make up a jumper wire with spade or round ends that fit th eplug you should be fine. I think those are a 5 volt minimal amperage circuit and the sensor is either open or closed.

 

[Learpilot]

Thanks for the replies. Sounds like maybe a band adjustment might be the answer. Another issue that I am having is reverse. When the truck is cold, and until I have cycled in out of reverse a few times, the transmission slips into reverse. If I get impatient and give a little to much throttle, it bangs into reverse. I think 3rd and reverse are on the same band. I understand that the adjustment procedure is to torque to 72 in lbs then back off. I am not clear on how many turns to back off. Can somebody advise please?

 

[cerberusiam]

Reverse is the rear band and direct clutches applied at the same time and forward clutches off. The front band is off in reverse. If this only happens when it is cold, idle the truck in neutral for several minutes before trying to engage any gears ot get the fluid circulating. If that doesn't help, you have soome internal wear issues that are causing low pressure cold.

The front band adjustment will depend on whether you have a 47RH or 47RE. All the RH's were generally 2 1/2 turns back off. The RE's were 1 3/4 to 1 7/8. On a worn trans you might have to drop 1/2 turn to keep the timing close.

 

[Learpilot]

Thanks cerberusium. My truck is a 96 so it should be the 47RE. I have to admit that I am a little confuses on the band adjustment. I have seen at leat 3 different adjustment specs on this and other forums. One guy on the Cummins forum claims that the service manual is wrong because 96 was the first year for the 47RE and Dodge forgot to change the spec. He says that theory is proven by the fact that Dodge did change the spec for 97 to 1 7/8 turns front and 3 turns rear. What do you think.

 

[cerberusiam]

MY 96 was the switch over year for the RH to RE, both transmissions were used in the 96 trucks hence the difference in the specs. The manuals were all printed before the 96 trucks started hitting the lots so they gave the specs for RH. When the RE started showing up there was an addendum to the manuals on the spec change on adjustments, it just did not get to every manual and owner.

You need to verify which trans you have to know which adjustment to use.

 

[Learpilot]

It looks as though I have a 47RE. I really don't know how to tell the difference except I read somewhere that the RE has 8 wires going into the case and the RH has only 3. Mine has 8 (or so). Do you agree that this is a proper method of determining the model? If you agree, I will use the 97 spec.
What is your opinion on what type fluid to use? Thank you for your help.

 

[cerberusiam]

Yeah, if you have an 8 wire harness its a RE unit.

The 97 spec seems to be the most reasonable to start with. If it is too tight you will feel it on the 2-3 shift as it will bind. Some of the builders will recommend 2-2 1/4 turns but that is on a new build. With some wear you might need it tighter. The front servo may have more wear in one spot rather than the other that will mess with the timing as will direct clutch pack wear. The biggest thing to look for will be your shift quality.

I use ATF+4 in all my transmissions. About as good as you can get.

 

[Learpilot]

Thanks cerberusium. I'll let you know how it all works out.

 

[BigPapa]

Just relaying my experience with a 47RH.

It started out doing what yours is doing, delayed 2-3 shift. I talked to a friend that's been building Dodge trannies for 30 years. He told me I had a seal leaking pressure internally, I think he called it a "lip seal" or "front lip seal", and that I would start eventually lose reverse. The delay got worse and finally one day, I had no reverse.

May not be related to your problem and may not have happened to the 47RE. Don't know.

 

[Learpilot]

Well, got the bands adjusted up, new filter and fluid refilled and the test drive went well. Thanks to all that helped! Next project is try to get the front rotors off so they can be turned and replace leaking left rear axle seal.

 

[Learpilot]

I guess only time will tell. Thanks for the input BigPapa. Middle TN, I get back there several times a year, Cookeville specifically. Beautiful country!