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U0102 SERV 4WD warning

sentfrommyifone

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Joey
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2019 JLUR 2.0L
I'm having some issues with my 2019 JLUR. A few weeks ago I replaced my batteries (genesis 2.0 dual battery system), and after a couple of weeks I got an error at startup that the sway bar disconnect was unavailable, serv 4wd, & collision avoidance was disabled. I had driven an hour from home and had no issues on the drive out. I drove home and have been driving around town for a couple of weeks trying various troubleshooting when I've had time.

So far I've disconnected the accessory battery and the genesis solenoid, effectively taking it out the loop. I had a z-locker that I removed (https://www.zautomotive.com/products/z_lkr_oem). I got one of those bluetooth ODB sensors and tried removing the error codes. U0102 stays and says it's permanent. At one point I also saw a U0168 error code, but it hasn't returned in a while. I also have a Tazer JL mini (have had it for like 5 years, no issues so far). Haven't removed/unmarried it yet, but that might be next.

I did observe something weird waiting to pick up curbside groceries the other morning. While idling, a fan kicked on abruptly at high RPM and about a minute later I got a coolant temp warning. I turned the Jeep off and that probably hasn't resurfaced (but I haven't been idling much since then).

Any ideas of what I should check next? I'd like to avoid the stealership and tend to do my own wrenching for basic stuff. I even resorted to asking chatgpt, it thinks I need to replace the TCCM. But I'm not sure I want to start buying parts based on some AI diagnostics.

I appreciate any advice y'all might have.
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sentfrommyifone

New Member
First Name
Joey
Joined
Oct 22, 2025
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Location
Austin TX
Vehicle(s)
2019 JLUR 2.0L
Wound up taking it to the shop to diagnose. Fuse F40 kept blowing, and the root cause was a pass thru connector at the rear differential was leaking fluid and shorting out the actuator. Replacing the connector cleared the fuse pops, and my error codes.

The coolant problem was that a heater supply hose had broken down.

Just posting in case someone googles their way to this post troubleshooting similar issues down the road.
 
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