Strange Issues, Rubicon wont start

[hcpcjj]

My 2019 Rubicon Won't Start

2019 Rubicon 4DR. Had been on vacation & did a remote start when I got home just to let it cycle. Started right up. Went to start it this morning, the dash said remote start disabled, start vehicle to reset. Tried to start, message went away. Nothing else happens. Dash is completely blank now. No response at all to the start button. Other symptoms, I can lock the doors, but they won't un-lock with the FOB. If I lock the doors & get out, sometimes they automatically un-lock after 5 seconds. Other times, I get the flashing security armed blinking light on the dash. If I re-enter by using the key, alarm goes off & cannot turn it off with the FOB. I'm in a real pickle. Something else weird, if you hold the start button, after about 15 seconds, the RPM and speedo start pinging in the negative direction. We live on a narrow driveway at the top of a hill. I doubt I can get a car hauler up here to tow it to a dealer. It won't go out of park & the steering wheel is locked so I can't roll it down to the bottom. Any help or suggestions are appreciated. Here's what I've done:



1. Checked voltage on both batteries. Both reading almost 13V.

2. Tried jumping and a battery charger with start mode. No change.

3. Did the auxiliary battery delete by pulling fuse F42 & disconnecting the auxiliary battery ground. No change.

4. Pulled the main fuse array & checked continuity on all.

5. Thoroughly cleaned all battery terminals.

6. Pulled & checked all fuses with a meter.

7. Disconnected both grounds & positive for 15 minutes to allow everything to drain & reset.

8. Replaced battery in FOB (I get a red light on the FOB when I press the unlock button)

9. Tried 2nd FOB

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[mwilk012]

How did you check the aux battery? Main?

It sounds dead. Did you remote start it then never go actually open the door and turn it on, letting it time out on the remote start and shut off on its own?

 

[hcpcjj]

How did you check the aux battery? Main?

It sounds dead. Did you remote start it then never go actually open the door and turn it on, letting it time out on the remote start and shut off on its own?

I did let it time out on its own. Battery charger reports voltage, also verified with a meter. Did not load test, but it zips the snow plow winch up and down quickly.

I did the aux battery delete by pulling the fuse & disconnecting the ground cable for the aux battery. It measured right at 13V from ground to positive with the positive cable disconnected from the main battery.

 

[hcpcjj]

I did let it time out on its own. Battery charger reports voltage, also verified with a meter. Did not load test, but it zips the snow plow winch up and down quickly.

I did the aux battery delete by pulling the fuse & disconnecting the ground cable for the aux battery. It measured right at 13V from ground to positive with the positive cable disconnected from the main battery.

Also, it has no problem blasting the horn when I open the door.

 

[Phantom01231]

How did you check the aux battery? Main?

It sounds dead. Did you remote start it then never go actually open the door and turn it on, letting it time out on the remote start and shut off on its own?

That’s what it sounds like the OP did.

@hcpcjj sounds like you triggered the anti theft. Unlock the doors with the fob then try starting it with the key fob like you would if the fobs battery was low.

 

[hcpcjj]

That’s what it sounds like the OP did.

@hcpcjj sounds like you triggered the anti theft. Unlock the doors with the fob then try starting it with the key fob like you would if the fobs battery was low.

I have tried that with both key fobs. Both with new batteries.

 

[mwilk012]

If true, the testing from this point on gets much more complicated.

If you’re measuring 13V, that’s not right. Batteries simply won’t hold 13V, unless you’re just rounding up from the actual 12.7.

Check the z case fuses, then it’s going to have to get into the communication network to determine if the BCM is receiving a wake up or start signal or not. Do you have a good scanner?

 

[hcpcjj]

I disconnected both grounds last night, put the battery charger on all night directly on the main battery posts. It started this morning. Seems to be running ok, but has a check engine light and says service tire pressure monitoring system. Everyone was saying batteries. It was evidently the main battery since the aux battery wouldn't have been charged with the ground disconnected. Not sure what would have caused this. I did start it with the remote and let it timeout prior to this occurring. Not sure if I should go ahead & replace the main battery or monitor & see if it does it again. I really appreciate all of the good & sound advice.

 

[yokramer]

I disconnected both grounds last night, put the battery charger on all night directly on the main battery posts. It started this morning. Seems to be running ok, but has a check engine light and says service tire pressure monitoring system. Everyone was saying batteries. It was evidently the main battery since the aux battery wouldn't have been charged with the ground disconnected. Not sure what would have caused this. I did start it with the remote and let it timeout prior to this occurring. Not sure if I should go ahead & replace the main battery or monitor & see if it does it again. I really appreciate all of the good & sound advice.

Your aux battery being dead is a drain on your main battery and will kill it prematurely as well. Replace your main, and remove your aux and fuse 42 (or loop the aux positive battery cable back to the main).

 

[shagles]

Just to be extra clear, did you ever try to start it with the FOB pressed to the start button?

 

[hcpcjj]

Yes, multiple times & multiple FOBS. Evidently, charging the battery fixed it.

 

[shane h.]

Get a new H7 AGM main battery.
Get some new fender clips. Search on Amazon.
Remove the old main battery.
Pull the passenger fender. You will break some clips. This is where the new clips come in.
Remove the Aux battery.
Run the positive/hot wire from the Aux battery well up to the area where new main H7 battery will set.
Put the fender back on.
Install the new H7 main battery in the main battery well.
Attach the positive/hot from the Aux battery to the main H7 battery positive lead set.
Remove the ground from the main H7 battery lead set that runs down to the Aux battery well and tape/zip tie it off.
Reattach the positive lead set to the new main H7 battery.
Reattach the negative lead set to the new main H7 battery.

Welcome to never having to worry about an Aux battery again.

I did this on my 2019 in 2021. I have never thrown a light or a code with this setup. I do use a Tazer to keep ESS turned off, but ESS will work if you want it to.

Takes about as long as it took me to type all of this.

 

[hcpcjj]

Thank you. Can I accomplish the same thing by pulling F42 & detaching the ground? I just replaced the aux battery about 9 months ago. The main battery was replaced a little over a year ago with a Die Hard H7 AGM from Advance.

 

[mwilk012]

Yes, multiple times & multiple FOBS. Evidently, charging the battery fixed it.

Yea, because it was dead. Your method of checking doesn’t work.

 

[yokramer]

Thank you. Can I accomplish the same thing by pulling F42 & detaching the ground? I just replaced the aux battery about 9 months ago. The main battery was replaced a little over a year ago with a Die Hard H7 AGM from Advance.

Yes you can just disconnect the ground for it, tape up the end and remove fuse 42.

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