The Dreaded Transmission Chirp

[931RamNoob]

2016 2500 4x4 6.4L. I purchased it used in ‘23. The dealer had just had the transmission rebuilt. Went into limp mode halfway into the 4hr drive home. Solenoid failed. Took it back. The trans shop did a warranty repair and supposedly upgraded to a heavy duty solenoid. Everything has been good until now (well out of warranty). When it downshifts from 6th to 5th or 5th to 4th I get the chirp, and sometimes it’s an extended chirp with a hard shift when it finally “connects.” It doesn’t matter whether I’m towing or not. It was an intermittent issue in the winter, but now it’s constant. The only work-around I’ve found was setting the manual shift to 4th, but now that’s even starting to feel suspect. I love my truck. Where do I go from here? Is there a heavy duty version? I thought it would have that with the “Heavy Duty” badges on it. Never had a code come up.

 

[mtofell]

Sounds a lot like the ever problematic valve body that plagues the 66RFE. I believe there are upgraded/aftermarket ones out there and that it's a pretty quick swap. My 66RFE has failed twice (38K, 90K) and is holding at 138K. In my experience, codes are VERY rare when these trannies have problems.

My first failure occurred when I was in stop/go traffic on the freeway towing/hauling nothing. Traffic took off, I pushed the gas, engine revved, and I moved at about 6mph. I limped it along to an exit, had to go uphill a bit to get off the freeway.... slipping and banging the whole time. I finally found a parking lot to pull into and lost all forward gears. Had to back into the parking spot and as I came to rest I got a CEL. Great, thanks for the warning

I actually hammered it on purpose because it was under factory warranty and I wanted a new tranny. Nope.... rebuild and it failed again at 90K (thankfully covered under extended warranty) From what I learned talking to the dealer and looking at the replaced parts list, the valve body was largely to blame both times.

 

[buckeyexx]

Not sure what would be heavy duty about the solenoid pack. I do agree you more than likely need the valvebody replaced. You can get a new or remanufactured updated valvebody that has been built with some upgraded internals like springs and plate.

 

[samsdad02]

I'll be doing this at first signs of an issue. https://nextgendiesel.com/products/...4&_sid=dd86d31f6&_ss=r&variant=41427015958701

 

[Ribtipram]

Just went through the same thing. Clutches went bad. I was having the 5 and 6th to down shift problem. I ended up with a trans replacement and a couple more clutch disk in the 66rfe problem area. Trans was toast. Check your fluid, if it's got any dirt on a rag it's your Clutches. Wasn't hard to change the trans but make sure you do the trans relearn before driving it or you will be doing it again shortly. I wasn't that mad because I got 189k out of it with towing a boat and a 37ft fifthwheel.

 

[Ribtipram]

I also drove with it limited to 4th for awhile. You can only do that for so long.