Get your Clutch Volume Indexes Right Here!

[nondem]

You folks may remember this thread I posted a while back about reading my Clutch Volume Indexes. This is to help me decide if the trannny has enough life left in it to warrant replacing the solenoids to fix the now very-occasional missed 1-2 shift.:
https://wranglertjforum.com/threads/reading-cvi-with-a-10-elm-327-dongle.65704/

So, it took me a while to get around to testing this and IT WORKS!!
I got the Clutch Volume Indexes for my 03 42RLE w/135k miles.

The website for this software has the look of one that may go down at any time and I don’t think this app is on the author’s ‘front burner” …but I did save it all for posterity.
https://jee34.weebly.com/

Sooo, as I said above -*It works*- I got my CVI numbers. The app is focused on the CVI data but I did read my VIN. I don’t have a check engine light so I can’t attest that the DTC part works for you peasants that do

I put several hundred miles on the Jeep recently w/o resetting anything so these numbers should be somewhat normalized.

This is the output when i selected “CVI Values”:

CVI Low/Reverse: 43 (Normal is 35-83)
CVI 2nd/4th: 73 (Normal is 20-77)
CVI Overdrive: 119 (Normal is 48-150)
CVI Underdrive: 39 (Normal is 24-70)

The numbers are all mostly in the middle-range except for the 2/4 which is where the solenoid issue has been happening. Not sure if that value being at the upper end is a true indication the clutch-pack for 2/4 is worn and almost at the end of its life(73 vs 77+).
Anyone have a clue?

Anyway - couple of notes for the future person on the same quest trying use this software:

Need a laptop with Bluetooth or a Bluetooth dongle.
I used Windows 11.
A generic ELM327 worked fine for me.
Pair with the ELM327 first.
Run the app as administrator.
Be tolerant of lockups and needing to kill/reopen the app.

 

[flyinfish]

Since the CVI measurement is a numerical volume of fluid and yours is at the high end of spec, I'd say the 2/4 clutch material is near end of life. Why it's the only one nearly out of spec is the mystery.
I included Tech Bulletin #1377 that states when it updates the TCM and other info.

 

[nondem]

Since the CVI measurement is a numerical volume of fluid and yours is at the high end of spec, I'd say the 2/4 clutch material is near end of life. Why it's the only one nearly out of spec is the mystery.
I included Tech Bulletin #1377 that states when it updates the TCM and other info.

Thanks for the added info...that specific document didn't come up in my searches. I think you are right, the pack appears to have more wear.

Although I've not had a single missed shift since putting the transmission cooler on, Very occasionally - in certain situations I notice what I could only describe as a rough engagement of that pack. It makes the shift quickly with no slipping afterwards but I feel a VERY slight buzzing sensation when going to 2nd at a certain speed and power-level. It's the kind of subtle thing you only notice if you are very familiar with a vehicle.
I suspected the solenoid is sticky or similar and that is what I'm feeling...and that is either because the pack is worn or it helped cause the pack to be worn....not sure, but it doesn't matter.

The trans has cherry-red ATF-4 in it and seems fine other than that...we will see how long it actually lasts. I built this Jeep as a weekend/vacation-to-Windrock trailer-toy but I keep driving it to work and such just for the pleasure of it...It puts a smile on my face every time I drive it. So, the miles are starting to accumulate faster....

FYI - for anyone interested: Uncle Tony's Garage (Youtube) has run his jeep over 40k miles w/a loud knock and it's still going....he is mid-rebuild on a 4.0 core he bought to replace it with.

 

[flyinfish]

Here's another Technical Bulletin #990.
Finding the small amount of information out there specifically for the 42RLE isn't easy. After some reading, if you see the CVI value in it's live state and not just a past snapshot then you can confirm it's actually worn media. From what I understand, you can get low values that aren't captured outside of real time and can be caused by line pressure, cross over seepage, etc.
When I had a shift solenoid go bad in my chevy pickup, there was no intermittent, it just didn't shift. Replaced the solenoid and off to the races.
In the future when you eventually rebuild the trans, a shift kit would certainly save clutch media but at the expense of harder shifts.

I find it very interesting just how many sensors there are on vehicles and the multitude of ways they are measured. On top of that the different networks that they communicate together on is fascinating.

 

[flyinfish]

One more Tech Bulletin to save as a 42RLE owner.

Interesting tidbit from the first paragraph of document.

"Beginning at the start of production for the 2003 model year, Chrysler Corporation modified the 42LE (606)
transmission and turned it into a Rear Wheel Drive called the 42RLE.
The majority of the transmission’s internal parts as well as operating strategy is virtually identical as the 42LE
with the exception of the rear drive section and the hypoid style final drive being eliminated. This
transmission is available in both 2WD and 4x4 configurations. The gear ratios and clutch application are also
the same as the 42LE."