Automatic shifter assembly failure

[Fergshouse]

I have a 2020 Sahara JLU that I bought Dec 2023 with just under 5,000 miles (it was a lease vehicle in pristine condition). I have the 2.0 turbo e-torque engine and automatic transmission. The other day when it was cold, after I started it the PRNDL lights were flashing and it would no go out of park. It took 7 or 8 restarts before it would go out of park and then the CEL was in. Drive it home and took it into the CDJR dealership the next day.

After diagnosing, they said the whole shifter mechanism needs to be replaced. Of course it is out of the basic 3/36 warranty and they said the shifter is not covered under the powertrain warranty as it is not technically part of the powertrain. The other bad news is they said it will be Jan 6th before the parts are in and total cost will be over $1400.

Has anybody else had this happen? Looking through other threads I saw a few mention shifter problems, but not sure how wide spread of an issue this really is. I guess I’m just bitchin’ about it, but definitely not real happy.

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[Phrank]

What codes did it throw?

My Jeep did the exact same thing when the canbus failed. A battery issue would also cause this. A canbus or battery failure would generally have other symptoms, but not necessarily. Before you throw out the big bucks for a shifter assembly, you definitely want to eliminate the cheaper/simpler potential causes.

 

[alphawolff]

The PDRNL lighting up indicates can bus failure. While I have seem the ESM fail on these, it is much more likely to be the connector at the r/f fender liner having connection issues. It is very common. There's multiple threads with write ups on how to fix it.

The DTCs can be checked to see what modules are losing communication. If it's the TCM primarily then it's definitely the connector.

It could also be the can-bus connector, but seriously unlikely on a 2021. That's a 2018/19 MY issue

 

[Phrank]

It could also be the can-bus connector, but seriously unlikely on a 2021. That's a 2018/19 MY issue

I don't want to derail OP's thread, but I'm curious as to why it's more prevalent in the early years - did they use a higher quality canbus in later models, or is it that the part degrades over time meaning that the probability of failure increases with age?

 

[alphawolff]

I don't want to derail OP's thread, but I'm curious as to why it's more prevalent in the early years - did they use a higher quality canbus in later models, or is it that the part degrades over time meaning that the probability of failure increases with age?

I'm not sure. I have replaced nearly 100 on 2017 Pacificas at this point. Very common on for that year and it's the same part used for the JLs. You can literally smack the glovebox area of the dash and everything comes back online. I'd suspect it's a combination of material and age related oxidation.

 

[Fergshouse]

Thank you all for the quick responses. The jeep is still at the dealership, but I’m planning to get it back instead of keeping it there waiting for parts. Will check the things you guys mentioned and post back what I found.

 

[Fergshouse]

So, unfortunately it looks to be the shifter assembly. The batteries load test fins and could not find anything with the canbus system. Nothing loose and no loose fuses. Looks like I’ll move forward with the shifter replacement. Thanks again for the input!

 

[ImLostAgain]

It could also be the can-bus connector, but seriously unlikely on a 2021. That's a 2018/19 MY issue

Forgive me if a Newb question. You are speaking of the 'star connector', green behind the glove box? My understanding is these are just CANBus hubs - similar to old networking hubs that just repeated messages to all connected devices. I *might* be looking at an issue with this part and based on your comments it is not unusual to have issues with it over time? I have a 19 JLU

 

[alphawolff]

Forgive me if a Newb question. You are speaking of the 'star connector', green behind the glove box? My understanding is these are just CANBus hubs - similar to old networking hubs that just repeated messages to all connected devices. I *might* be looking at an issue with this part and based on your comments it is not unusual to have issues with it over time? I have a 19 JLU

I am indeed speaking of that connector. They're called star connectors internally in our parts system. They are indeed just hubs, but they're important in that they each contain a 120 ohm resistor required for can-c communication. There's two per network, 120 each for 60 overall. In vehicles without them the resistors are internal to some module instead


Honestly I have no idea what goes wrong with them, maybe internal corrosion or something. Bad solders? I've never broken one day to see if I can determine the cause, but they're a common issue from 2017-2019 or so. 2017s (pacificas) especially.

 

[ImLostAgain]

I am indeed speaking of that connector. They're called star connectors internally in our parts system. They are indeed just hubs, but they're important in that they each contain a 120 ohm resistor required for can-c communication. There's two per network, 120 each for 60 overall. In vehicles without them the resistors are internal to some module instead


Honestly I have no idea what goes wrong with them, maybe internal corrosion or something. Bad solders? I've never broken one day to see if I can determine the cause, but they're a common issue from 2017-2019 or so. 2017s (pacificas) especially.

Thank you for the quick reply. From what I have read, it seems those parts do fail and can cause random, intermittent CAN - C comms issues. From you comments, MY 18 and 19 seem to see this?

I was a computer hardware technician in a past life (Apple computer in R&D) so have some skill in diagnosis. Not a huge fan of throwing parts at things, and if low cost and low risk with known issues, then it is not always a bad thing .

 

[alphawolff]

Thank you for the quick reply. From what I have read, it seems those parts do fail and can cause random, intermittent CAN - C comms issues. From you comments, MY 18 and 19 seem to see this?

I was a computer hardware technician in a past life (Apple computer in R&D) so have some skill in diagnosis. Not a huge fan of throwing parts at things, and if low cost and low risk with known issues, then it is not always a bad thing .

They're cheap and easy to replace. Generally if I see one from those years come in with 70+ can DTCs I just immediately replace it without giving it a second thought. If the issues return we can go down that rabbit hole

 

[ImLostAgain]

They're cheap and easy to replace. Generally if I see one from those years come in with 70+ can DTCs I just immediately replace it without giving it a second thought. If the issues return we can go down that rabbit hole

Thank you for all the info! It is greatly useful and appreciated.

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