Gear Ratio Error in 4th, 3rd and 2nd

[jgruberman]

Yesterday out of nowhere I threw a CEL P0732(Gear Ratio Error in 2nd) and the truck went into limp mode. I did a one time reset and of course it came back. I also got P0734("" in 4th) and P0733("" in 3rd) today after driving it gently a bit.

I have a tuned truck, and do a decent amount of boat towing to add context to the workload on the transmission, additionally it's a 68RFE. The truck has about 145k miles on it.

Hopefully someone knows some info on here that might help me get some insight and determine what my next steps might be. It may just be bring it to a shop but I'd like to try and figure out some info about what's going on first... thanks in advance to anyone who can help...

 

[Timd32]

Someone else might jump on this one with some hands on experience.

I'm working on my PhD in copy paste, but I do try to read about the things before I just screen shot and dump these things on there.

Simple common point is Fluid Level Low, also one has a broken or cracked filter, with improper seal on filter.

I feel I have read that before on these the filter housing can break. Again just a WAG, someone can correct that, I seem to recall you have to just becareful to get the filter seated properly.

So you could do some real simple checks.

Then it's all looking at common points off the screen grabs, or wait for help to arrive. There are some pretty slick 68RFE folks lurking, just need to lure them out with some bad info to correct...... I'm thinking let's not start with the Failed Spline on the Reverse Annulus Gear to Input Carrier.....

 

[jgruberman]

Thank you for the info! I did check fluid and unfortunately, it's fine. I'm starting to think there is something wrong with the clutch itself only because of the intermittent slipping(I assume that's what Incorrect Gear Ratio means) in gears 2-4.

Most of my driving lately is taking my 22' pontoon boat back and forth to the lake, but wondering if between the constant towing, the truck tune on a stock transmission, and being at 145k miles that something has just "given up"....

 

[Timd32]

I could not do it, but look at the above stuff and manually check the common issues, then can kinda get a rough idea.

I tried and the screen shot deal just does not work for that long of a post.

Unless you know you broke it there are some items there you can address for sure. Then you just need to figure out if any of those can be eliminated.

Just for the entertainment value check out Precision Transmission. I love watching his tear downs. They are in Amarillo, TX. He might have some info on the 68RFE. I wish I had a pen and paper and wrote down all the stuff he listed on the 47RE videos, he has some good tricks buried in the videos.

Seems like a really cool shop and lots of knowledge there. Only 10hr round trip from Dallas. Alot of people actually seem to get a hotel room for a day or so when getting stuff worked on their.

https://youtube.com/c/PrecisionTransmission

 

[bcbender]

My brother's 1500 had ratio errors among many others trans related and it turned out that his aftermarket replacement transmission filter had split the seam and was sucking air so not getting enough pressure to hold. Aftermarket filters splitting are a known issue on the 545RFE and 68RFE and MOPAR now put a relief check valve in to prevent this phenomena where in a certain situation there is a momentary pressure spike on the suction side. Did you do a trans service recently? Use non MOPAR filter?

 

[Blackbrush]

Your 68 is toast. RevMax..... Been there and done that. I drive an Aisin now and have never been happier.

 

[jgruberman]

My brother's 1500 had ratio errors among many others trans related and it turned out that his aftermarket replacement transmission filter had split the seam and was sucking air so not getting enough pressure to hold. Aftermarket filters splitting are a known issue on the 545RFE and 68RFE and MOPAR now put a relief check valve in to prevent this phenomena where in a certain situation there is a momentary pressure spike on the suction side. Did you do a trans service recently? Use non MOPAR filter?

Since owning the truck, I haven't touched the transmission unfortunately so nothing aftermarket or filter work done

Your 68 is toast. RevMax..... Been there and done that. I drive an Aisin now and have never been happier.

RevMax? How much did your Aisin cost to get installed? I have a local shop quoting $4500 for a rebuild including upgraded parts for the tow/tune

 

[Blackbrush]

I put a RevMax in my '14 and it has been great with 140k on it now.
I bought a '20 HO.... 49k on it and has been amazing.

 

[bcbender]

How much did your Aisin cost to get installed?

Probably about 60~70k and came with a new body / engine..

Dont believe you can go from 68RFE --> AS69RC w/o changing trucks but maybe some else knows better.

 

[Cummins12V98]

"Dont believe you can go from 68RFE --> AS69RC w/o changing trucks but maybe some else knows better."

You may be right but I am betting a lot of $$$ would get it done!

 

[jgruberman]

Well I ended up having it towed to a shop(their cost) and they asked me a handful of questions when I first called. He asked what I did with it, how much extra power I'm getting with my tune and recommended he rebuild it with some beefier parts. He mentioned some I'd read about(I forget what they were) and said it would cost $4500 for the entire job. Based on what I'd read, coupled with Google Reviews(4.7/5 stars with 240 reviews) and how the conversation went, I was comfortable letting them tow it. He said they pay for it for a rebuild job, so that's a nice bonus.

Is this reasonable cost for what I assume will end up being a rebuild?

 

[Ozymandias]

The 68 can be beefed up to match almost any HP/TQ rating.
The Aisin not so much.

So make it match your Engine and enjoy.