Swapped 5R55S for 5R55W, should I swap pcm as well?

[Grant S]

I have a 2003 Explorer Xlt with the 4.6L V8, a few weeks ago the trans started to go out so I found a 2002 Explorer with a rebuilt trans with around 60K miles on it (verified with receipts) that the engine had self destructed on. I swapped them and have been driving it the past 2 weeks without issue. Now just a few days ago I realized that the trans from the 2002 is a 5R55W, where as the one I took out of the 2003 was a 5R55S. My question is, should the pcm also be swapped from the 2002 to the 2003 so it matches the 5R55W? Or would the pcm's be programed the same and the transmission is simply operated by sensor/pressure readings (if that makes any sense)? Any insight is greatly appreciated!

 

[imp]

I have a 2003 Explorer Xlt with the 4.6L V8, a few weeks ago the trans started to go out so I found a 2002 Explorer with a rebuilt trans with around 60K miles on it (verified with receipts) that the engine had self destructed on. I swapped them and have been driving it the past 2 weeks without issue. Now just a few days ago I realized that the trans from the 2002 is a 5R55W, where as the one I took out of the 2003 was a 5R55S. My question is, should the pcm also be swapped from the 2002 to the 2003 so it matches the 5R55W? Or would the pcm's be programed the same and the transmission is simply operated by sensor/pressure readings (if that makes any sense)? Any insight is greatly appreciated!

@Grant S
Are you positive the 2002 was a W? The difference is gear ratios, and I'm surprised driving with the S has not caused transmission codes to be thrown. No "OD OFF" light flashing? If there are no such issues, I would drive it and not worry about it. imp
@Grant S
EDIT: One other thing. The PCM in your vehicle is configured at the factory with the VIN, along with the ABS module. If you change the PCM, the new one will have the VIN of a different vehicle, and the ABS light will be illuminated constantly, creating the code VIN mismatch.

 

[Grant S]

@Grant S
Are you positive the 2002 was a W? The difference is gear ratios, and I'm surprised driving with the S has not caused transmission codes to be thrown. No "OD OFF" light flashing? If there are no such issues, I would drive it and not worry about it. imp
@Grant S
EDIT: One other thing. The PCM in your vehicle is configured at the factory with the VIN, along with the ABS module. If you change the PCM, the new one will have the VIN of a different vehicle, and the ABS light will be illuminated constantly, creating the code VIN mismatch.

The only info I had to determine the model of each of them was a Google search. The tag from the 2002 was a 1L2p-DE. And the tag from the 2003 was a 2l2p-DA. There is no flashing overdrive light, and the only code showing was for insufficient egr flow. So a pcm swap doesn't sound like a wise move, would it be possible to have the 2003 pcm flashed for a 5R55W? Or would there be no point to it? I just don't fully understand how these transmissions operate and am wondering if it is going to damage something if the computer is telling it to shift at a certain point thinking that the 5R55S is in there when it is not.

 

[imp]

@Grant S "would it be possible to have the 2003 pcm flashed for a 5R55W?"

Sorry, I just don't know. But as a guess, the program, the software in the PCM controlling the transmission function is very likely a proprietary thing, which if possible to work with, only a Ford dealer could do it, and even then I'm thinking probably not. imp

 

[Grant S]

Okay, well I appreciate the input anyway. I guess I got the idea that the program might need to be changed from youtube videos of guys swapping solenoid packs saying the transmission needs to relearn the shift points or something. I may attempt to rebuild the 5R55S in the event that the W fails. I didn't have to turn it in for a core or anything so I would only be out the new parts that I put into it should I screw up...

 

[rewind1]

I have a 2003 Explorer Xlt with the 4.6L V8, a few weeks ago the trans started to go out so I found a 2002 Explorer with a rebuilt trans with around 60K miles on it (verified with receipts) that the engine had self destructed on. I swapped them and have been driving it the past 2 weeks without issue. Now just a few days ago I realized that the trans from the 2002 is a 5R55W, where as the one I took out of the 2003 was a 5R55S. My question is, should the pcm also be swapped from the 2002 to the 2003 so it matches the 5R55W? Or would the pcm's be programed the same and the transmission is simply operated by sensor/pressure readings (if that makes any sense)? Any insight is greatly appreciated!

Hi @Grant S , I doing the same swap on my 2002 4.0L...

When you swapped the 2003's S tranny out for the W from the 2002, which harness did you use? Did you use the one that came with the W or did you use the harness from your original S? Did have to make any modifications?

What did you decide to do on the PCM? How has it been running the past 9 months?

 

[Grant S]

I used the original harness that was in the vehicle, did not have to make any modifications too it, everything matched right up. Left the PCM untouched as well, have not had any issues with it yet.....

 

[rewind1]

I used the original harness that was in the vehicle, did not have to make any modifications too it, everything matched right up. Left the PCM untouched as well, have not had any issues with it yet.....

Thanks very much for the reply.
I assume by "the vehicle" you are referring to the 2003 that you are driving.
I guess maybe that is my problem. I kept the harnesses with the trannys when i swapped and one connector doesnt fit. The firewall plug goes right in, but the smaller 8 pin just next to it has the little plastic wings in a slightly different spot so it wont fit.
I was worried about doing damage if I used the wrong harness but given your success, I guess i can tackle swapping it this week.
Thanks again!

 

[GWF]

Hi @Grant S , I doing the same swap on my 2002 4.0L...

When you swapped the 2003's S tranny out for the W from the 2002, which harness did you use? Did you use the one that came with the W or did you use the harness from your original S? Did have to make any modifications?

What did you decide to do on the PCM? How has it been running the past 9 months?

The 2003 harness I have but it doesn't plug in at the pcm so I used the 2002 so since I don't have the 2003 pcm I think I'll have to do some more searching one guy said I have to put the some of the older transmission to the newer housing but I'm not sure about that

 

[mhcody44]

How did the swap work out? Having some of the same issues and looking at changing 2002 explorer 5r55w with donor 2004 5r55s. know it is an old thread