Question for the Transmission gurus

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5 miles into my trip to the Texas Rally, my transmission decides to give me troubles. Problem is, the trany downshifts into 3rd gear(at least it seems like third). I know it's not just the T/C unlocking. One thing that I did notice, when I started it up to leave the trans temp light stayed on. I killed the engine and restarted it, and the light went away. I know it wans't hot because it had been sitting for 3 hours. The temp light does not come on when it downshifts, I thought to watch for that. I got under the truck and checked all the electrical connections and they are fine. Fluid level is fine and color looks good. Any suggestions?
BTW, It's a 94 with the 47RH transmission.

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"Big Red" 1994 Ram 2500 Laramie SLT, 12 valve, 2WD, Auto. 139,000 miles. I am my own warranty station Ranch Hand steel brush guard, Scotty Air, silencer ring put back in(wifey said so), Flowmaster muffler, chrome turn down pipe out the side, Velvet ride shackles. My Truck Site

 

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I dont know about the transmission guru thing , but i would try checking out the temp sensor.
Since you indicated the trans is not overheating by the feel and the temp indicator light is comming on i would check suggest the temp sensor.
The temp sensor is located on the front cooler line that comes out of the transmission by the shifter linkage and goes up to the heat exchanger on the passenger side of the vehicle.
Bill

 

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Is there a particular way to check that sensor or should I just replace it? It would only do this when pulling the trailer, otherwise it is fine.

 

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gitchesum,

I just replaced my sensor because it was leaking. It's pretty cheap as I recall and easy to replace so might as well go ahead and replace it. If it still does it then you know that the sensor is not the problem.

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Joe George
Eureka, CA

'95 2500 CC auto 4X4,3. 54,Combo EGT/boost guage,custom switch panel,PacBrake,TST #5,BD valve body,Automatic motorhome steps on both sides,Foldacover hard bed cover,Cummins chrome kit,Black steel grill guard,Front hitch receiver

 

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From what I understand (correct me if I'm wrong)if the temp sensor registers too hot it would kick you out of OD as a "safety feature" for those who can't read idiot lights. That may be why it kicked down and would be consistant with the light coming on.

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'94, 2500, 4X4, SLT, 3. 54 gears, Prime Loc, Silencer ring in the tool box, DeeZee bright tread running boards, side box boards and mud flaps. Alpine CD player. I cleared 100K mi while the board was down. Jardine Performance 4" exhaust (sounds just like a Pete, it's great)

 

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I changed the temp sensor and it seems to have corrected the problem. I haven't tried to pull anything yet. The only concern I had was, the light would ont come on when it would downshift. It only came on right after I started it. Everything seems OK now. Thanks for all the help.
BTW, there was some transmission fluid in the electrical connection. Maybe that was causing the problem too.

[This message has been edited by gitchesum (edited 09-25-2000). ]

 

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OK all you transmission experts,
My buddy bought a '98 12V 4X4 Quad cab Auto with about 85K on it. Lately he has noticed that the Auto trans will NOT shift into 4th when he has the OD off. With the OD on it 'seems' to shift normally although the shifts seem almost non-existant. I was expecting to see an RPM drop between 1-2, 2-3, 3-4 but it seems to hold the same RPM as the speed goes up.
He can only get the speed up to about 63 MPH unless he has the OD on. I've read all the posts I can find on this subject and I have a
question about the trans-temp sensor... How do you tell if it is defective? Is it a normally closed or normally open switch? Electronics I have no problem with... . I've NEVER owned an Auto Transmission. #ad

Any help or ideas would be appreciated.

Thanks,
Mick2500
<font color=blue>

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2001. 5 2500 ETH/DEE, QuadCab, 4X4, SB, LSD, 3. 54, SLT+, Sport, Intense Blue PC/Agate, Tow Package, Camper Package, 'DC' Bed Cover, Sliding rear window. Totally STOCK!!
On Order 4/28/00
Arrived 9/14/00 !! #ad




[This message has been edited by Mick2500 (edited 10-26-2000). ]

 

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The transmission is a three speed with an OD for fourth. So if you lock out the OD it won't shift to fourth unless it's busted.

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Joe George
Eureka, CA

'95 2500 CC auto 4X4,3. 54,Combo EGT/boost guage,custom switch panel,PacBrake,TST #5,BD valve body,Automatic motorhome steps on both sides,Foldacover hard bed cover,Cummins chrome kit,Black steel grill guard,Front hitch receiver

 

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Thanks George BUT I went and read the specs on Dave Fritz's page and the transmission is listed as a 4 speed with an overdrive lockup TC.

Mick2500

[This message has been edited by Mick2500 (edited 10-27-2000). ]

 

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Originally posted by Mick2500:
Thanks George BUT I went and read the specs on Dave Fritz's page and the transmission is listed as a 4 speed with an overdrive lockup TC.

Mick2500

[This message has been edited by Mick2500 (edited 10-27-2000). ]

Howdy,Mick-- the transmission itself really is a 3-speed. the TC will "lock" (electrically triggered, based on a computer decision, or an over-ride switch, commonly called a "mystery switch")
the overdrive unit is a small,separate transmission, mounted to the rear of the "real" transmission housing. it's a 2speed--"direct" 1:1 (just like 3rd) and O/D 0. 78:1
That's the 4th gear. . when the OD unit upshifts.
If he has the O/D OFF lite lit up, there's no 4th available. . the O/D unit stays in 1:1, and you have 3-lock as the highest gear.

In a stock transmission, the slip-shifts are very soft, nearly imperceptible, and with very little dip of rpms. it will feel like 4 gears when O/D is locked out... 1st "slip" up to about 4-8mph,2nd "slip" up to about low to mid 20's, 3rd "slip" to about 30mph, then 3rd "lock". That's as far as you get until you "click" the little O/D button, which makes 4slip and 4lock both become available.
4-lock is good up to about 100mph @ ~ 2500rpm w/3. 54's... any faster would require one of the following:
taller tires and Abbot adjustment computer doohickey
lower ratio rear gears, like 3. 23 or something (never heard available in a big Dana)
or a governor spring kit to get past 2500rpm

 

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Mick2500,

If you read the specs in the Dodge service manual you will see that it is like Rich says. THREE speed with OD to provide a 4th gear. The TC lock up doesn't change the gear ratio. It just stops the TC slipage so the result seems to be another gear. The OD lock out prevents it from shifting to the "4th" gear.

 

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Rich and Joe,

Thanks a bunch for the 'slush box' education. #ad
I'm forwarding this to my friend so he can see your responses. Sounds like his transmission is operating normally! Just didn't seem normal till I had your excellent descriptions of how it 'should' work.
I'm currently without my service manual. They sent what they 'thought' was a 2001 but it is the 'old' 2001 manual and does not cover the 'new' 2001. #ad


Mick2500
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2001. 5 2500 ETH/DEE, QuadCab, 4X4, SB, LSD, 3. 54, SLT+, Sport, Intense Blue PC/Agate, Tow Package, Camper Package, 'DC' Bed Cover, Sliding rear window. Totally STOCK!!
On Order 4/28/00
Arrived 9/14/00 !! #ad


[This message has been edited by Mick2500 (edited 10-28-2000). ]

 

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rich m,

Great description! You've put me at ease, also. I bought my CTD used and have been waiting for trans failure because of soft shifts and no RPM drop. Gotta tell you, you've made my day!


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'95 2500 SLT LB 2WD, auto 3. 54, 67,000--Westech gauges, Prime-loc, Brite box, Back-off Box, Line X, Flowmaster muffler, Borgeson steering shaft