Remote start not working after setting 24 hours - battery voltage all over the place

[mtudb24]

Long story short. Last fall I lost the aux battery. Truck died in my driveway at 8V. Tied the negative ground cable up and pulled fuse 42. Truck ran fine from Oct 2024 to Jan 2025, when my battery voltage went to over 16V and turned on every light on the DIC and multiple messages about traction control not available etc. (Truck is a 2021 bought new in Oct 2020). So I was happy i got 4 plus years out of the aux battery. Figured my main battery was shot.

Replaced it in Jan 2025 with a new Group 94 and everything was great until last Thursday when my remote start didn't work but didn't think anything of it until yesterday when I tired to remote start it again and it didn't work. I gave up on watching my voltage gauge cause it would fluctuate between 13V and 15.3V as members said it was normal operation.

I did do a IBS reset after I put the new main battery in. However, my remote start won't work if I let the truck set overnight. My battery voltage is setting at 11V when I just depress the start button after a failed remote start by the keyfob. if I drive the truck for 20 mins and go into a store for any length of time and come out the remote start works fine.

My LED headlamps with resistors which worked fine are now flickering bad. I did buy a tazer to change that setting but haven't had the time to install it yet.

What are the chances I got a bad battery that I replaced 3 months ago? Or are these LED headlamp bulbs causing an issue? They aren't cheap knock offs and many member including people on the Jeep Wayoflife (ie Eddie) group are running them on the the JL's and JT's with no issues. Or could my alternator be bad or a bad IBS sensor?

Thanks for your recommendations.

Sponsored

 

[ALT2870]

Does it detect the key fob at all? Some of us have had issues when the FOB is cold it won't work until it warms up. (Though sounds like you have a different issue altogether.)

 

[mtudb24]

Does it detect the key fob at all? Some of us have had issues when the FOB is cold it won't work until it warms up. (Though sounds like you have a different issue altogether.)

The truck beeps only once and won't start when I click the remote start button. Doesn't matter if I use either FOB.

 

[ShadowsPapa]

Long story short. Last fall I lost the aux battery. Truck died in my driveway at 8V. Tied the negative ground cable up and pulled fuse 42. Truck ran fine from Oct 2024 to Jan 2025, when my battery voltage went to over 16V and turned on every light on the DIC and multiple messages about traction control not available etc. (Truck is a 2021 bought new in Oct 2020). So I was happy i got 4 plus years out of the aux battery. Figured my main battery was shot.

Replaced it in Jan 2025 with a new Group 94 and everything was great until last Thursday when my remote start didn't work but didn't think anything of it until yesterday when I tired to remote start it again and it didn't work. I gave up on watching my voltage gauge cause it would fluctuate between 13V and 15.3V as members said it was normal operation.

I did do a IBS reset after I put the new main battery in. However, my remote start won't work if I let the truck set overnight. My battery voltage is setting at 11V when I just depress the start button after a failed remote start by the keyfob. if I drive the truck for 20 mins and go into a store for any length of time and come out the remote start works fine.

My LED headlamps with resistors which worked fine are now flickering bad. I did buy a tazer to change that setting but haven't had the time to install it yet.

What are the chances I got a bad battery that I replaced 3 months ago? Or are these LED headlamp bulbs causing an issue? They aren't cheap knock offs and many member including people on the Jeep Wayoflife (ie Eddie) group are running them on the the JL's and JT's with no issues. Or could my alternator be bad or a bad IBS sensor?

Thanks for your recommendations.

Did you fully charge the new battery before installing?
Have you made sure the battery terminals are TIGHT, you can't move or turn them? (it's a common problem)

 

[Mr._Bill]

The truck will easily start with low voltage, but Remote Start stops working when it drops below 12.2 and will start working again as soon as the battery gets a charge.

The new battery is probably okay. It just needs to be fully charged and have the IBS reset. These vehicles have a high parasitic draw, especially with the 8.4" screen. If they are not driven enough to keep the batteries charged, it leads to issues like you are having now.

You could have alternator issues, but a full charge with a AGM charger should get you going again. If you are not driving it daily, a battery maintainer should be connected.

 

[mtudb24]

Did you fully charge the new battery before installing?
Have you made sure the battery terminals are TIGHT, you can't move or turn them? (it's a common problem)

Hey Papa. I did not charge it when i bought it. I put a volt meter a crossed the terminals and it read 12.4V before I left the store which I thought was good. I would have thought if it was low on charge from the get go, I would have run into this issue sooner then 3 months later.

Yes, the terminals are torqued down. No wiggle going on at all.

Maybe I need to take a long trip to fully charge the battery which I have not done in weeks if not the last month. my longest drive has been 30 or so minutes.

 

[Mr._Bill]

Fully charged, with no load, the battery should read 12.8 volts and be able to hold it at that level for quite some time.

 

[mtudb24]

Fully charged, with no load, the battery should read 12.8 volts and be able to hold it at that level for quite some time.

Thanks for the info. There is no lag time when trying to start the Jeep. It fires up right away with no prolonged / slow cranking at all. Watching the Voltage gauge it goes within One second of 11V to 14 once the alternator kicks in. So maybe I do have a bad battery or a battery that isn't fully charged. But then again I would have assumed this condition would have presented itself the day I changed battery back in Jan 2025. I never had any symptoms of the remote start not working or the LED headlamp flickering when I originally changed the battery.

 

[ShadowsPapa]

Hey Papa. I did not charge it when i bought it. I put a volt meter a crossed the terminals and it read 12.4V before I left the store which I thought was good. I would have thought if it was low on charge from the get go, I would have run into this issue sooner then 3 months later.

Yes, the terminals are torqued down. No wiggle going on at all.

Maybe I need to take a long trip to fully charge the battery which I have not done in weeks if not the last month. my longest drive has been 30 or so minutes.

That's way low. All batteries should be charged, on a good AGM charger, before installation. The alternator isn't meant as a battery charger, it's meant to maintain charged batteries. Unless you drive for hours at a time, it will never catch up.

One thing to do would be to "start over" by charging the batteries independently (assuming you still have the auxiliary battery in the mix), and reset the IBS - putting it on fully charged batteries.

 

[mtudb24]

That's way low. All batteries should be charged, on a good AGM charger, before installation. The alternator isn't meant as a battery charger, it's meant to maintain charged batteries. Unless you drive for hours at a time, it will never catch up.

One thing to do would be to "start over" by charging the batteries independently (assuming you still have the auxiliary battery in the mix), and reset the IBS - putting it on fully charged batteries.

Isn't 12.6 the norm for resting voltage of a 12V battery? My aux batt is disconnected, so thats not part of the equation anymore.

 

[ShadowsPapa]

Isn't 12.6 the norm for resting voltage of a 12V battery? My aux batt is disconnected, so thats not part of the equation anymore.

That was the case before AGM batteries. Actually it was closer to 12.64 or something like that according to GM training materials.
AGM batteries should rest, NO LOAD, fully charged, at 12.7-12.8
If they are connected to the Jeep, they are under a small load.
Once a good charger is done with an AGM battery, it will likely read over 13 then settle down once the surface charge is removed to be closer to that 12.7-12.8 area.

Sponsored