Started having transmission issues with weird shifting into 4th gear and would seeming be in neutral and rev really high, suddenly it got stuck into 5th gear and wouldn’t shift out, regardless of speed (tried select shifting as well, nothing) and extremely harsh shifting between P/R/N/D with wrench light. I also noticed my transmission cooler fans go into high during this time even though temp isn’t above normal. I read the codes and it came up as shift solenoid C electrical circuit as well as a misfire code. I figured it was likely a lead frame issue. So I replaced the lead frame, fired up good, ran a PCM test, followed the steps to relearn the transmission. Was fine for about 15 miles and boom, exact same issue, stuck in 5th. This time code is coming up as output shaft speed sensor circuit no signal. While in the truck, if I clear the code with FORScan the problem completely goes away and shifts normally for a few minutes and then comes back. Cold starts are also fine but once transmission temp gets to operating temp, it throws the code and goes into limp mode. Looks like the speed sensors are on the lead frame that I just replaced. I took it took it to the dealer and of course they “can’t read the codes” because of the whipple tune on it. Picking it back up tomorrow. Wanted to see if you guys had any ideas I can try before taking it to a performance shop. I’m thinking maybe an electrical issue of some type? Was planning on checking and cleaning all the connections leading to/from the transmission. Any help would be great!

Thanks !

Specs: 2017 F150 5.0, 6r80 transmission, 2.9L whipple super charger

 

Since you have codes for electrical issues, I'd say you have electrical issues. It probably isn't the leadframe, but the wiring between the PCM and the leadframe. A bit of electrical diagnosis should find the problem.

 

Cool. Just got it back. Going to buy some electrical connector cleaner and go through the hiring harness between the two and see if I can spot the problem. Will post update after i finish that step. Thanks!

 

That seems like a major waste of time. You need a VOM, a wiring harness, and some knowledge of how to diagnose wiring issues. Looking at it is almost always a waste of time.

 

I’m wondering if I have the same issue. Same year , trans, and motor , trans decides to shift down to 3rd on its on and sometimes it seems like it shifts to neutral. Then back to normal. Lights on the dash for the transmission (PNDM12) will disappear and come back. Codes, P0706, p0707, p1702, and p1921. I just had lead frame changed. And I hope that fixed it. But I’m kinda doubtful.

 

Not sure if you are still having issues, but you might check out this. The 5.0L have camshaft sensors on same circuit as transmission range line. Link gives some troubleshooting steps.

https://www.techshopmag.com/diagnosi...07-p1702-p1921/