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Discussion Starter #1
Vehicle - 2000 Dodge Ram 2500 4x4 / 5.9L8 / Automatic Transmission / 202k miles

My transmission shifts through gears 1-4 seamlessly but when it hits the 5th gear the engine revs up and the transmission drops back to 4th gear. It's acting as though there is not sufficient oil pressure to maintain or hold the 5th gear.

By the way, there are no codes coming up.

Is it possible that this can be an electrical problem as I'm being told or is the transmission on its way out? Can someone please advise as to the nature of what this problem can be and a possible solution?

Thanks in advance.
 

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Admin - David Mack
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You didn't say which trans is in the truck but I'm guessing it's the 47RE. One common but weird problem is the throttle position sensor (TPS) signal from the ECM to the PCM. Check out the Technical Service Bulletin - TSB 18-02-99. Bad connects or a bad battery can cause some odd problems in all the Dodge Rams new and old. The 2Gen are bot the smoothest around so double check the connection around the ECM and PCM.

When was the last time the filter and AFT was changed? While the pan is off, did they or you can do a band adjustment and upgrade the gov pressure solenoid & switch. With that kind of mileage, it should help.

Without knowing more, I cannot think of anything else off hand.
 

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Discussion Starter #3 (Edited)
Thank you for your reply.

With the problems you suggested, will these give any CODES?

The oil and filter were changed yesterday. We also added a bottle of LUCAS treatment, but that didn't solve the problem.

I'm glad that the suggestions you made didn't include the transmission needed to rebuild.

Where can I get Technical Service Bulletin - TSB 18-02-99 please?
 

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Discussion Starter #7
Yes you are correct this tranny has 4 gears. It shifts 1-3 seemlessly and then when trying to get the 4th gear the engine get erratic and then drops back to 3rd gear. As long as I drive below 40mph the truck rides smoothly. Only when shifting to 4th gear there is an issue.
 

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It's acting as though there is not sufficient oil pressure to maintain or hold the 5th gear.
Well you can test that, Here are the test ports.

May also be an issue with the od solenoid.
 

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Discussion Starter #9
I just tested the TPS on a SnapOn Solus Ultra diagnostic unit and the maximum voltage I'm getting is 3.56VDC when the accelerator pedal is fully depressed and 0.57VDC when accelerator pedal is at rest. Is this the correct volts?? I though maximum should've been 4.5-4.7VDC.
 

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Discussion Starter #10
Guys thank you all for your helpful replies. I was hoping I could drive my truck at 40mph since that's all the tranny would give me until I could afford a rebuild but now my engine died and I'm getting CODES P1688 and P0251. Is there anyway that driving my truck with this tranny issue would've cause me to lose my pump?

I know this is not the Engine section of the forum, but since the two seems related that just added it here. I could post it in the other forum if needed or the MODS can move it for me.

Thanks again
 

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Check your codes/truck id!

Vehicle - 2000 Dodge Ram 2500 4x4 / 5.9L8
P0251 CP3 Pump Regulator Control
P1688: INTERNAL FUEL INJECTION PUMP FAILURE
These are diesel codes! Did you post the wrong info because your truck id says gas?
 

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Discussion Starter #13
Would someone please help me to understand this:

Above you see where my transmission would not hold 4th gear. I had this problem for about two months. Just as I was about to replace my transmission with a rebuilt one costing $1800 because no diagnostic codes were coming up, I lost all engine power and was getting codes P0251, P1689 and P1688. Now I know those codes refer to my fuel pump. So I replaced the fuel injection and lift pumps and all codes went away. To top it off, I don't have the transmission problem anymore.

Could someone please explain to me how this could be?? Is my transmission bad or not or was it an electrical issue with my transmission that manifested itself through the failed fuel injection pump and after the failed fuel pump replace problems were solved??
 

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Discussion Starter #14
Guys I really need some advice here....

My transmission was just newly rebuilt using all new parts including a new torque converter and my truck still has this problem. What could the problem possibly be with the transmission dropping from 4th gear to 3rd gear.
 

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If it were my Ram, I'd solve the known error codes and go from there. My only thought would be the computer is limiting the trans, a limp mode, because of the engine's error codes. It may well be that there's not one thing wrong with the transmission. Sorry, my knowledge on diesel engines and transmissions is kinda basic and I maybe as full of shit on this but that's my best guess here. You could try clearing the codes and see if errors come back. Disconnect the batteries, put them on a charger, wait at least 30-minutes before hooking them back-up, and then see what the truck does after that.

:imo
 

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It is hunting between 3rd & 4th gear basically the torque convertor is locking and unlocking. Some use the BD diesel noise filter which works.
Check out this guys page he has found a permanent fix rerouting the ground cable that is near the alternator.

http://www.kentsoil.com/dodgebug1.htm
 
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