Zman, I tried that last week and it didnt work, so I took it to autozone to run their code checker and nothing came up.

Heyyou, I did check it in neutral with the ebrake on. I might take it in to get the tranny fluid changed or at least drain it so its not overfilled. I will try the straight road test tonight, I can do it during the day, I live 30min from Washington DC and the traffic almost never dies down here >

 

I have 35's "315's" on mine.. and at 70 I'm only bout 1750 .. 3.55 gears.. but i have a 5 speed

 

Just got back in from the drive test and the results are what I expected, no 3 to 4 change. I didnt get above 60mph but in my experience the OD kicks in before that. Soooo no OD light in the dash and no 3 to 4 gear change leads me to believe the OD isnt working. It shifted fine from 1 to 2, 2 to 3, and the tcc worked (small change of rpm) Is there a fuse that could be burned out? I hope thats what it is but I will feel like an idiot

 

In the power dis box under the hood there is a relay in spot C. In the dash it's a 10 amp in spot 9. this is for a 96 so please double check.

 

I just got back in from messing with the truck. I looked at the fuses and they all look fine, but I havent tested the relays (not sure if theres a relay for OD). I ripped off the instrument cluster and to my surprise there was no bulb for the O/D OFF indicator. So i just took the one from my washer fluid low light and the light works now when I press the button on the end of the shift column. After putting it all back together I still have the same problem. When it should be shifting into 4th gear it doesnt, and when I press the O/D button, regardless if it is turning the light on or off, the rpms actually go up a few hundred rpms sometimes and then down a few hundred rpms. I'm probably going to take it to take it to a transmission shop and see what they say.

 

Ok, I'm pretty old school here, but is it possible with the 3:55 gears, that the engine is under too much of a load (lack of vacuum?) to make the shift into O/D ??
Like I said, I'm old school, so this idea may be totally useless! LOL

 

I currently have the same exact issue on my truck. Reason is because I have a 2000 PCM in a 1999 Truck. 2000 PCM is looking for 2000 transmission sensor outputs, because its getting 1999 sensor outputs the PCM doesnt allow or isnt compatible enough to send a signal for the Torque Converter Clutch or Overdrive to engage.

Did you buy the truck when it was new? Are you certain that the PCM is the original? Did your Truck ever shift into OD and just recently start not to? PCM has to be fore the exact model year of your vehicle. If its not the same model year, that right there could be your issue. Otherwise if not, there could be some bad sensors inside your tranny. The electronic parts in the tranny related to TCC and OD are

Main Internal Wiring Harness W/ External 8 Pin Plug attatched, Overdrive & Lock-Up Solenoids, Governor Pressure Transducer, Governor Pressure Solenoid.

Available through Ebay ( http://cgi.ebay.com/ebaymotors/SOLEN...Q5fAccessories )

If it's not the PCM or Electronics, then something physically may be wrong inside your transmission. I would give you a link to the 2001 dodge ram service manual for assistance troubleshooting but i cant find the link.

Hopefully if someone knows what the link is they will post it.

One thing that stands out to me on this issue is that your if your TCC isnt working, a part that fails rarely by the way, your issue is probably something electrical. Check that PCM, Wiring Harness, and electronics in the tranny. 2001 Service manual says that you can test the electronics in the tranny using a continuity tester.That shouldn't be too hard if you pull the valvebody, the harness you can check visually for cuts in the line or debris in the connector, and the PCM you might have to call the dealer about. May have to go down there to have them cross reference the numbers printed on the thing and to check the version but from what I know, those are the options.

 

you definately dont have stock gears! at 70mph my truck runs a 3k rpm. i dont have overdrive either. but mine is due to the fact that i have a 2001 truck with a 1998 transmission, so there are a couple internal sensors not working because of that. make sure whenever you drive your truck to press the button to shut your overdrive off cause if you dont you could cook your transmission due to overheating cause of the way its trying to shift into overdrive but cant because of the sensors.

 

wait...i just replaced my t-case (98 case) and i have no speedo hense no O/D....tranny shifts mint up through the three gears, i have O/D on (no light) and have no TCC lockup when im traveling 2200 rpms to work in 3rd gear.....am i hurting my tranny??

the speed sensors from my 95 bad case and 98 case had the same part numbers on the spindle gear, piece that sensor goes in, and the sensors, but the hook up connection was different...so i have the 95 sensor in it.....but everything had the same part number stamped on it......wonder what could be my issue.....had speedo before the change, should i buy a new sensor?



sorry im not trying to hijack the thread.

 

I do have tcc lockup and when I toggle the od switch I get a small reaction in rpms so I believe there is a connection. I bought the truck a couple weeks ago so I'm not sure of its history. I asked the previous owner for any information and he didn't do any of the work on the truck as he bought it in its current state. Ill be going to a tranny shop to see what they say and get back to you. Thanks for the info.