3.7L V6 QT1 to QT2 Conversion.

[cmdr jim]

Test results so far. No vibrations up to highway speeds. If anything the drivetrain feels tighter. I did notice the NV140 had more backlash than the NV245. My NV140 has 66000 miles and the NV245 only had 11000 miles, that may be the reason. Also, I did a final drain on the NV245 and what oil drained looked very good.
I tested with the Jeep in gravel, High to High lock works and Low and Low Lock work. The speedometer is correct even in Low Lock. No "Check Engine Light" the first time I used Low Lock, I left the transmission in drive.
The second test I shut off the Jeep then restarted and shifted the transmission to 1st gear, I ended up with a Check Engine Light, Code "P0700". I don't think it went into Limp Mode. I shut it off and put the transfercase into High, tried resetting the fault with HyperTech, but it didn't remove the "Check Engine Light", however the Jeep shifted correctly and I can manually shift through all the gears. More testing I need to understand this.

[Sal-XK]

I think you nailed it man awesome work!

[stites-xk]

Awesome work

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[Ross]

Good job!

[cmdr jim]

I think you nailed it man awesome work!

It does look like it's working, I just need to test some more to see what is happening with the codes in Low. I can tolerate error codes when in Low, as long as it doesn't adversely affect anything else.

I think this is what is taking place when I shift to Low or Low Lock:

First it is going into Permanent Limp-In Mode
"If this occurs while the vehicle is moving, the transmission
remains in the current gear position until the ignition is turned off or the shifter is placed in the "P" position. When
the shifter has been placed in "P" the transmission only allows 2nd gear operation. If this occurs while the vehicle
is not moving, the transmission only allows operation in 2nd gear."

And once I shift the transfercase back into high it goes into Temporary Limp-In Mode
"This mode is the same as the permanent Limp-In Mode except if the condition is no longer present, the system resumes normal operation."

Which would explain why after I receive the "Check Engine Light" and shift the transfercase back to high the transmission operates correctly. By going out of Low and back into High, I've "fixed" the condition that put the TCM into Permanent Limp-In Mode, and placed it into Temporary Limp-In Mode.

Question, how long does the error code stay in the TCM, but operate correctly before the code disappears or does it need to be reset by disconnecting the battery?

[LWM]

Question, how long does the error code stay in the TCM, but operate correctly before the code disappears or does it need to be reset by disconnecting the battery?

In most cases it takes three starts of the motor to clear codes as long as the problem has also been corrected (you cannot just start it and turn it off, you must drive between starts).

[cmdr jim]

In most cases it takes three starts of the motor to clear codes as long as the problem has also been corrected (you cannot just start it and turn it off, you must drive between starts).

Just confirming, that appears right. The "Check Engine Light" is off, keep in mind there were never any shifting problems in "High" during the error.

[cmdr jim]

I think I have come up with a way to eliminate the Low Lock error code completely. It would require another wheel sensor and 4 relays. Spot welding equally spaced targets on the rear driveshaft flange up by the transfercase, and mount the wheel speed sensor to the transfercase to read these targets. Then when in Low or Low Lock switch on the relays with my program to read this wheel sensor, instead of the actual wheel sensors.

[07JeepXK]

Good luck with that. lol thats way beyond my knowledge!

[Matt]

I think I have come up with a way to eliminate the Low Lock error code completely. It would require another wheel sensor and 4 relays. Spot welding equally spaced targets on the rear driveshaft flange up by the transfercase, and mount the wheel speed sensor to the transfercase to read these targets. Then when in Low or Low Lock switch on the relays with my program to read this wheel sensor, instead of the actual wheel sensors.

I think I see what you're trying to do.... but that would only work if the gear reduction in the tcase is the same as the gear reduction in the axle (in other words the axle RPM out of the tcase in Low is equal to the wheel RPM when not in Low)..... or did I misunderstand the concept?