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47RH Problems ( big surprise )

Discussion in 'Ram Trucks' started by KC9MDQ, Dec 3, 2010.

  1. KC9MDQ

    KC9MDQ Member
    Messages: 35

    Howdy all . We have a 1995 Ram 2500 with the diesel and the 47RH trans . I just had the trans rebuilt about 4,000 miles ago , ( the truck has 266,000 + miles on it ) and suddenly , out of the blue , no overdrive ! Shifting from first through third is fine and it seems that the torque converter clutch is locking up , but pressing the overdrive disable button makes absolutely NO difference in the behavior of the truck . I know the obvious answer is check the switch , does anyone else have any thoughts ?
    For what it's worth , the L.E.D. in the switch turns on and off as normal .
  2. plowguy43

    plowguy43 PlowSite Fanatic
    Messages: 5,264

    I'm willing to bet its a sensor on the tranny. I can't remember which one though.

    Go here: dodgetalk.com , there is tons of info there.
  3. mnglocker

    mnglocker Senior Member
    Messages: 922

    There's a speed sensor near the tail on the of tranny on the lower drivers side that gets all buggered up with break in crap when you rebuild them. Take the sensor out and clean it up with a little non-chlorinated brake cleaner, reinstall and top off your transmission fluid with ATF+4.

    DAFFMOBILEWASH PlowSite.com Addict
    Messages: 1,581

    Could also be the temperature sensor on the trans cooler line acting up. Why not go see the mechanics who did the rebuild ???
  5. KC9MDQ

    KC9MDQ Member
    Messages: 35

    The Mech is closed on weekends, and my day job is from six am to five pm ,the mechanic closes at four thirty . I would have asked him to stay late ( he has before ) but I have ENTIRELY too many things to do this weekend , big family christmas today about 50 miles away , ( travelling with another vehicle ) , I plan to dink around with it tomorrow . On top of everything else , it snowed three inches overnight ! Fortunately , I operate on a " you call , I push " basis , and only have one customer who never calls unless there is five inches or more of accumulation . I already informed him earlier in the week that I couldn't come out until Sunday , so everything is good there.
    I will let everyone know what I figure out . Thanks for the help , I really appreciate it .

    DIESELCHEROKEE Junior Member
    Messages: 1

    I have a 94 - same truck !

    Have had these issues in the past myself !

    Check the speed sensor (mechanical on your transfer case connection - this sends a message about the speed you are travelling at - to your computer- allowing the tranny to go into O/D)

    2.) check that the trans temp sensor on the output line to the computer is hooked up and plugged in - when it's cold - if this sensor does not gain enough heat - your truck will not go into overdrive - perhaps the tranny shop ? didn't hook it up due to the fact that OEM replacement lines are NLA from Dodge for the 94/95 tranny - which have a pre-formed female port for the switch to screw into - if that's the case, you can buy enough brass hdwe/fittings - this must be as close to the tranny as possible so that heat is not lost prematurely from Home Depot/Lowes or your local hrdwe store - to cobble the same in your output line to the tranny cooler - if you find the temp sensor there hanging - I have tie- wrapped it against the line so that it gains heat and also duct taped around the switch once it's tie-wrapped to insulate against heat loss once the tranny is at operating temp (obviously a longer time when temps drop) If your switch is MIA - you'll need one plugged into the harness or you'll never get O/D with a 94/95 set-up - 96 and newer is different - no external temp switch!

    3) lastly the TPS swich on your P7100 injection pump may be faulty (black switch held on with 2-3 small bolts/screws - a new one can be purchased at Auto Zone/Advanced Auto ?

    My guess, knowing that you had you tranny done 4000 miles ago when it was warmer - it's the temp switch issue being your problem !

    Hope this helps you ! - Barry

    DAFFMOBILEWASH PlowSite.com Addict
    Messages: 1,581

    Hey Barry, I have a 95 which is late going from 1-2.... All the rest is good other than OD is a tad early and NO kick down. Do you think it is a issue with the kick down cable??? Also once and a while the pressure needed to press the acellerator differs too. You can be driving and all of a sudden the pressure changes. Changing from hard to push to very EZ....

    My 93's had a issue with the kick down cables sizing up once and a while too. Not sure if the 95 is much the same.
  8. mnglocker

    mnglocker Senior Member
    Messages: 922

    The 95' technically has a Throttle Valve Cable, and it sounds like it's out of adjustment.

    Take and relax the cable, then have someone hold the accelerator pedal to the floor and take all the slack out of the T.V. Cable.
  9. KC9MDQ

    KC9MDQ Member
    Messages: 35

    Well here's an update . We are 99% certain that the problem is the aforementioned temp sensor . The trans is only buggy when very cold out . I couldn't really find much reference to it in the Haynes manual ( big surprise ) , so . . . . . . . it SHOULD be on the driver's side of the trans almost to the tail shaft ?
    Does anyone have a part number so I might order one from the parts store ? I am reasonably certain I can figure out the removal / installation process .
  10. mnglocker

    mnglocker Senior Member
    Messages: 922

    The location you're mentioning is the speed sensor. The temp sensor is going to be near the cooler line I/O's. Forward and on the drivers side.

    DAFFMOBILEWASH PlowSite.com Addict
    Messages: 1,581

    Temp sensor is on the trans line running to the front of the truck. Follow the linkage for the gear sector down to the bottom. Has two wires on it and a plug. Looks almost like a temperature sensor or oil pressure sensor. Ez in and out.

    Tv cable was all out of wack. Much better for driving now. The truck will kick down but still shifts late into 2nd. All other gears perfect. At this point I am starting to think it needs the 1st gear reverse band backed off a hair. This in theory reducing the line pressure needed to shift into 2nd....
  12. Get Plowed AK

    Get Plowed AK Member
    Messages: 78

    After building a few Dodge plow truck trannys. Changing all the sensors and whatnot. more common than not, after installing a shift kit or any other line pressure altering holes or checkballs. It would be the overpressure sensor to push the transmission into "Safe Mode" wich will only allow the truck to opperate in 2nd/3rd. Shutting down and starting again will solve this issue for the time being. However an inline resistor will need to be installed on a wire exiting pcm. maybe different but thats always been my troubles.
  13. justme-

    justme- 2000 Club Member
    Messages: 2,138

    FWIW, the RH has no real electronics in it, pressures and shifting is purely mechanical based on the governor- the RE starting in 96 has electronic gov.

    I've been told there is no safe mode in the RH or limp mode- when the RE has some issue the gov get's no power witch keeps it from shifting into 1st as 2nd is the default.

    DO NOT back the band adjustment off to change the shift characteristics- the band adjustment is to create the proper tension and proper engagement in the bands- set them correctly or you will induce increased wear to them and poor performance.

    These transmission have the propensity for the TV cable arm on the transmission to bind up from salt and rust- it needs to be cleaned/lubed/de-rusted/etc and ensure the TV cable is PROPERLY adjusted and that is moved correctly. If the cable binds at the arm the shift points (especially 1st to 2nd and 2nd to 3rd) will be late because the TV cable is altering the line pressure in the TB which moves shift points based on what engine speed/drivetrain speed it "thinks" the truck has.
    Happens to mine almost every year and some penetrant on the pivot for the TV arm followed by some elbow grease and white lith solves it.

    lack of OD can be from several things- the switch on the dash is a momentary that sends a ground pulse to the PCM which stores the state of the OD- if the PCM loses power for any reason (key off, engine speed sensor faulty, ground bad) it will loose that state defaulting to od on. When in doubt change the switch for the light, but the light is replaceable if you have the incling- just a grain-o-wheat bulb. Depending on your driving habits and your gearing you really should be driving with OD off unless you're driving fast enough for it to stay engaged- normal city driving will cause the od to engage at about 40 and disengage frequently, which causes undue wear since the line pressure and such are lower than they really should be plus the od is only engaged by a spring....
  14. damian

    damian Senior Member
    Messages: 330

    if you have a factory service manual or alldata and you look carefully,you will find resistance values vs temperature for the temp sensor,i have situations where we could not get a temp sensor or the line was not available that it went in.we got a resistor matching a 70degree value wired it in place of the sensor and off you go,just cancell od yourself until warm up.

    DAFFMOBILEWASH PlowSite.com Addict
    Messages: 1,581

    So, here is where I stand. Have removed every cable and rod, inspected for non fluid travel and out of adjustment issues. The TV rod is where I think the issue is. As I shorten the rod the idle increases rapidly. I don't think the rod is pulling enough on the injection pump to create full throttle. So is there a seperate ajustment screw for the idle???

    Truck also seems to be running very fumey and not the greatest on fuel. It is getting closer but still not up to my standards.
  16. mnglocker

    mnglocker Senior Member
    Messages: 922

    Do the 3 turns of the key trick and pull the codes and tell us what you got.
  17. plowguy43

    plowguy43 PlowSite Fanatic
    Messages: 5,264

    This thread should be a sticky, there is a ton of info about this tranny in here!
  18. KC9MDQ

    KC9MDQ Member
    Messages: 35

    Well , this Saturday I changed the trans temp sensor in the line. What a world of difference it made ! ! ! The truck has NEVER driven this well , not even the day I drove it off the lot ! Thank you SO MUCH everyone , for your suggestions and advice. I drove it to Appleton and back ( about 250 miles for me ) and she used less than a half tank ! With the TQ solidly locking it made a huge difference in fuel mileage , good thing with what #2 diesel costs these days ! Agaim , THANK YOU EVERYONE ! ! !