47re no overdrive signal

[Jeremy175]

I recently bought a 2001 4wd Cummins with an automatic transmission. The transmission was slipping in 2nd gear, but all the other gears worked great including overdrive. I swapped a 2wd transmission from a 1997 into the 2001 and now I do not have overdrive. I drove the truck before the swap, so I know all the gears worked. The swap consisted of installing the 4wd overdrive housing with transfer case on the 2wd transmission, and I had to swap the neutral safety switch due to the plugs being different. I have checked pin 6 (brown wire) at the transmission plug and it has a constant 13-14 volts when driving the truck. The pcm isn't sending the signal to the overdrive solenoid. Where do I go from here? Is the 97 transmission temperature sensor different from 01?

 

[Timd32]

IMO they do not appear to interchange the 2001 looks like a 2000ohm, the older 1000ohm. Book reads like you can't do that as you have it now. Does not say you cant swap some stuff around. The connectors look physically different some else familar with that might chime in.

Reccomend you pick up an ATSG 47RE book they have some basic diagrams and explain some of the internals on the various types.

 

[Jeremy175]

I'll see if I can order that book online. Where exactly is the temperature sensor? I know it's in the pan, but where at in the pan? Someone said it's actually the transducer beside the governor control pressure solenoid, is that correct?

 

[Timd32]

Yep its on the side of the Gov Pressure Body that fits flat on the Valve Body.

Lot of folks upgrade to the GM version of that assembly, it looks to have a 4 flat pins stacked vertically.

I dont know if you can take the one and put it in a older trans, or you should get the GM style and new harness, then reuse your old one.

It's the Gov Pressure Sensor and Temp sensor in one part.

 

[Jeremy175]

You are a lifesaver!!!! I just ohmed the trans temp sensor in the 97 transmission and it reads 1k ohms then I ohmed the trans temp sensor in the 01 transmission and it reads 2k ohms. That has to be what is holding me out of overdrive!

 

[Timd32]

It looks like they have different clips to hold them in, not sure if they will plug and play in that block.

The overall kit is a little pricey, as is everything for a 47RE at times, you might have to swap some stuff over to make the 2 play nice.

https://www.thoroughbreddiesel.com/...EGq2tP9DgHCKpOIAGOK4My__3VBka5shoCa5AQAvD_BwE

 

[Jeremy175]

I tore my old transmission apart and the harness can be swapped over, then I will be able to plug in the newer transducer which will read 2k ohms instead of 1k ohms. I am thinking of tricking the pcm at the moment with a 2k ohm resistor to try and make sure this is my issue. I feel pretty sure it is, but I would hate to swap everything over and still not have overdrive. Do you think the difference in the sensor resistances is most likely my issue?

 

[Timd32]

Right now its thinks its too cold for OD, so 2k would work IMO. The higher resistance the hotter it thinks it is.

Just remember it uses that dual sensor for the overall gov. pressue sensor, so when you do it just make sure thats in a good spot and you dont lose that signal. Other then that I dont see the difference in the pressure signal side of that part noted anywhere.

 

[Jeremy175]

That's right I forgot about the transducer reading pressure too. And I wasn't sure if the lower resistance was cold or hot. Make sense now, because I haven't had a trans temp light come on if it were reading hot. I really appreciate your help!!!!!!

 

[Timd32]

Never a problem, someone else would have jumped in and helped, if you stick around you will find some great folks on here.

I just happen to be working on my 47RE recently so some of it is easier for me to find.

Good luck, if you get it all.figured out post the final results of what you had to do to get it all figured out.

 

[Jeremy175]

If I have enough time tomorrow after work I am going to swap the harness/transducer over and see what it does. I will post the results

 

[Jeremy175]

So, I swapped transducers and the wiring harness inside the transmission and that fixed overdrive and lockup. Thanks for the hep!

 

[Timd32]

Sounds good. Enjoy your new ride.