The Ol' Transmission

truckbouy2 · **Posted:** Wed Jun 17, 2020 8:38 am

Been a long run with the hard shift and all, but the Jeep is finally is close to terminal. My wife drove the Jeep and said she pushed the OD button to disengage (fortunately she was going slow) and the back wheels locked up momentarily. Scared her. So we put the Jeep in the "to do" pile. I drove it one day to check this out. So at about 65 mph I pushed th OD button to engage the OD. Locked up the back wheels like when you were a Kid skidding your back tire on your bike. At about 30 mph the wheels started rolling again. Drove it home. It drives fine (except for the hard shift issue) with OD disengaged. When I hit that button and she locked up I figured I'd have parts and oil on the road for a 1/4 mile, but no such luck. I was impressed at the strength of the 545...

truckbouy2 · **Posted:** Thu Jun 18, 2020 9:28 am

Not being as well trained on the 545, anyone out there have an "educated" guess on just what has gone awry. I haven't pulled any codes as it's not worth the cost to have it done. In 50 years of transmission both catastrophic & minor failures, they usually just blow apart (this one remained drivable but without OD) when something like this takes place.

flash7210 · **Posted:** Thu Jun 18, 2020 12:39 pm

because its locking up soon as it tries to shift into OD, that can pretty much be narrowed down to the OD clutch assembly.
and locking up like that is very unusual.
so maybe there is a overrunning 1-way clutch inside that is locked up?

Hexus · **Posted:** Thu Jun 18, 2020 1:44 pm

Usually the only thing that goes wrong with these transmissions is the solenoid pack has an issue. I changed my Solenoid pack 2 times in 263k miles and except for one wiring short that fixed everything.

I would check there first. Also, before you do any work get it to a Transmission shop and have them run a deep scan on the error codes on the Transmission specifically. That will narrow it down quickly.

Hexus · **Posted:** Thu Jun 18, 2020 1:48 pm

Also, if the Transmission cooler isn't pulling it's weight (Clean it first, cheapest) the TCM will lock out the silly 5th gear, and that may be an issue.

Check your fluids and ensure they're way above the full mark on the dipstick since the OEM dipstick is wrong, and you might look into changing fluids and filters and even adding an accessory cooling unit (fairly inexpensive).

Just more thoughts as I was navigating away in my random and rare visits.

truckbouy2 · **Posted:** Thu Jun 18, 2020 2:33 pm

Hex.. When we bought this one it was a Chrysler program Jeep so it had the 8/80,000 warranty. Jeep screwed with this transmission for 2 years. It's had valve bodies, solenoid packs, tcm's, that's right, all plural. It's been drb'd and learned about 6 times. All the EXTERNAL stuff you could possibly do, it was done and that was just for the hard 2-3 shift. Chrysler had no idea what was happening. Then all of a sudden about a week after the 8/80 ran out, "we have to tear it down" to see what's wrong. That's when Chrysler and I were no longer exchanging Christmas cards. The hard shift has been an issue for years but the rear wheel lock up recently started that's why it's in the "to do" pile. I was curious like I said, because I had never had one lock-up and remain drivable with out leaving all the parts on the road. I have a 2014 65 out of a 1500 I'm going install. If I get some down time, I'll gut the 545 to see what's broken. And thanks Flash that was one thing I suspected but you all here are pretty wise and insightful with this stuff.

WWDiesel · **Posted:** Thu Jun 18, 2020 2:35 pm

Hexus wrote:

Usually the only thing that goes wrong with these transmissions is the solenoid pack has an issue. I changed my Solenoid pack 2 times in 263k miles and except for one wiring short that fixed everything.
I would check there first. Also, before you do any work get it to a Transmission shop and have them run a deep scan on the error codes on the Transmission specifically. That will narrow it down quickly.

X2, Very good advice!
More than likely is an electrical/solenoid problem since it only happens when he uses the OD button.
Fix may be just replacing the solenoid pack...

flash7210 · **Posted:** Thu Jun 18, 2020 3:27 pm

another thought

jack up the rear axle (or all 4 wheels it you want to test the transfer case), start the engine, and run it through all the gears.
see if it still locks up when going into OD

edit

another thought
if you jacked all 4 wheels off the ground and engaged 4-low, that will keep the driveshaft and wheel speeds down, reducing any jarring to the driveline if it does lockup or suddenly switch to reverse
(when I do this I put jack stands under the front lower control arms)

truckbouy2 · **Posted:** Fri Jun 19, 2020 8:38 am

WW, if it still was the original solenoind pack I would supect it but this 'ol Jeep has had (2) valve bodies, (2) solenoid packs, (2) tcm's, not including the originals. Wiring has been chased once and replaced once. Cooler and lines replaced once. I think Flash pegged it with od clutch assy. When I get some time after the swap I'll tear it apart and see whats missing inside.

The Ol' Transmission

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