New-ish JLU with battery issues

[DoctorRabbi]

Ok, for transparency – the JLU is my wife’s car – not mine. It’s a 2020 (purchased new in Oct 2019) and has 43K miles on the clock. Every service done according to schedule – mostly by me – with the exception of the dealer doing the windshield repairs/replacement, leather on seat replaced when stitching started unravelling and the head unit when Uconnect became inoperative.



Anyway, the car was parked in our garage without being used for 4 days (last week). Prior to this it always started up the first time without issue and never has had any warnings or errors. My wife gets in after her trip to surprise my kid after school and the car just clicks – doesn’t start. She calls me, I come over and jump start it. It starts fine and she uses it without issue the remainder of that day. The next morning, it wouldn’t start again so I stick it on a battery tender. It starts up fine later that day. I removed the tender when it read 14.1V because I figured it was ok. The following morning it doesn’t start again. Now I’m thinking screw this, I’ll just get a new battery and put it in. I know these have two batteries, a smaller aux under the fuse box, and a large agm 12v as the main battery connected in parallel. I figured I’d start with the main one and see if that fixes it. Went to AutoZone and get one of their Optima yellow batteries (since it’s my wife’s car and I don’t want her having issues – but holy crap sticker shock), get home and connect it all up. This is when the fun started.



The car started right up but would not go into gear... the auto box was stuck in Park. No check engine light but a warning on the console that says “service shifter”. W. T. F. Disconnected and reconnected – same thing. Took the battery out and stuck it in a rapid charger to 14.3V (it read 13.7 which was more than enough) and stuck it back in. Same thing. Everything on the interior seemed to work fine, radio, lights, Uconnect ... just the “service shifter” message and no go. I disconnected the main battery, removed it from the vehicle, and tried firing it up (easy way to test the aux battery), and it started right up without issue. But still the service shifter message remained. I really did not want to arrange for a tow, so I disconnected the negative terminal from the firewall so the aux battery would discharge and left it overnight.



This morning, I stuck the main battery back in, connected everything up and it started right up. Even went into gear. The “service shifter” message was gone but it had a cel and a message saying, “auto stop/start disabled – battery charging”. The battery charging message I expected because the aux was discharged but the cel was a pita. The code was u1267 (no can communication). I drove the car a few times for 30+ minutes every time without issue, but the cel never reset. After much troubleshooting I gave up.



I used my trusty old obd scanner to clear the code (cel gone), and though it still has the “auto stop/start disabled – battery charging” message, it seems to be all ok now. I figured the message may be there for a few days but if it doesn’t go away, I’ll replace the aux battery. I’m just really gun-shy now – never had a vehicle (and I’ve owned so many) that has behaved this way before. Yeah - ... if it’s a jeep thing, I don’t want to understand. Just hoping this helps someone else with troubleshooting a similar issue.

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[DWaX]

Replace or permanently bypass the aux battery. Both the oem batteries are notoriously garbage.

WaX

 

[smokeythecat]

Ugh. I don't have an aux battery, but my main OEM battery died after a few months. It was replaced under warranty but it made me jumpy. I'm planning on getting a Genesis dual battery system at some point.

 

[DWaX]

I've had the Genesis dual system on for about 1.5 years, fantastic product and piece of mind.

WaX

 

[mwilk012]

You made things much worse by not replacing the clearly bad aux battery.

 

[Jebiruph]

Ok, for transparency – the JLU is my wife’s car – not mine. It’s a 2020 (purchased new in Oct 2019) and has 43K miles on the clock. Every service done according to schedule – mostly by me – with the exception of the dealer doing the windshield repairs/replacement, leather on seat replaced when stitching started unravelling and the head unit when Uconnect became inoperative.



Anyway, the car was parked in our garage without being used for 4 days (last week). Prior to this it always started up the first time without issue and never has had any warnings or errors. My wife gets in after her trip to surprise my kid after school and the car just clicks – doesn’t start. She calls me, I come over and jump start it. It starts fine and she uses it without issue the remainder of that day. The next morning, it wouldn’t start again so I stick it on a battery tender. It starts up fine later that day. I removed the tender when it read 14.1V because I figured it was ok. The following morning it doesn’t start again. Now I’m thinking screw this, I’ll just get a new battery and put it in. I know these have two batteries, a smaller aux under the fuse box, and a large agm 12v as the main battery connected in parallel. I figured I’d start with the main one and see if that fixes it. Went to AutoZone and get one of their Optima yellow batteries (since it’s my wife’s car and I don’t want her having issues – but holy crap sticker shock), get home and connect it all up. This is when the fun started.



The car started right up but would not go into gear... the auto box was stuck in Park. No check engine light but a warning on the console that says “service shifter”. W. T. F. Disconnected and reconnected – same thing. Took the battery out and stuck it in a rapid charger to 14.3V (it read 13.7 which was more than enough) and stuck it back in. Same thing. Everything on the interior seemed to work fine, radio, lights, Uconnect ... just the “service shifter” message and no go. I disconnected the main battery, removed it from the vehicle, and tried firing it up (easy way to test the aux battery), and it started right up without issue. But still the service shifter message remained. I really did not want to arrange for a tow, so I disconnected the negative terminal from the firewall so the aux battery would discharge and left it overnight.



This morning, I stuck the main battery back in, connected everything up and it started right up. Even went into gear. The “service shifter” message was gone but it had a cel and a message saying, “auto stop/start disabled – battery charging”. The battery charging message I expected because the aux was discharged but the cel was a pita. The code was u1267 (no can communication). I drove the car a few times for 30+ minutes every time without issue, but the cel never reset. After much troubleshooting I gave up.



I used my trusty old obd scanner to clear the code (cel gone), and though it still has the “auto stop/start disabled – battery charging” message, it seems to be all ok now. I figured the message may be there for a few days but if it doesn’t go away, I’ll replace the aux battery. I’m just really gun-shy now – never had a vehicle (and I’ve owned so many) that has behaved this way before. Yeah - ... if it’s a jeep thing, I don’t want to understand. Just hoping this helps someone else with troubleshooting a similar issue.

Sometimes dead batteries will cause a software glitch that requires a power reset (disconnecting both batteries) to clear. That appears to be the case with your shifter issue.

I suspect your u1267 code (no can communication) was generated as the control modules were losing power when you disconnected the aux battery.

The “auto stop/start disabled – battery charging” refers to the main battery, not the aux battery. It's based on the battery sensor's analysis of the main battery.

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