More electrical gremlins.

[mtudb24]

Long story short. Bypassed my aux battery and pulled the negative cable and fuse 42 etc back in Oct / Nov 2024 when the aux battery took a dump and stalled the truck in my driveway at 9V. Then my truck went haywire and voltage on the cluster was 16+ volts and changed the main battery around Jan / Feb 2025 and upgraded to a 94R battery size. All was good after that. No issues

Yesterday, I tried to remote start the truck and it wouldn't work. Didn't think anything of it as I parked it on a angle towards the front and thought maybe I was low on gas (this has happened many times). But when I got in and manually started it, there was no low fuel light on. Then I noticed driving at dusk and all of a sudden my headlights were flickering really bad (LED's but changed to LED setting with the Tazer) and my cluster lite up for less then a half second saying service ABS multiple times. It was so fast, the cluster never gave an audible "ding". I could just see the flash of the round ABS light.
I also noticed voltage was 14.6-15.0 and coming to a stop it dropped to 11.6V and engine stuttered but then jumped right back up to 13V. I had the blower motor going (not on AC) but as the voltage on the cluster reached 14.7V or higher, the blower motor would shut off and then turn back on when the voltage went back down.

I have no additional electrical accessories besides the 3 KC's that are tied into the battery and on a toggle switch in the cab. I can't imagine anything drawing a parasitic load.

The remote start worked this morning heading into work but the blower motor was on and off depending on where the voltage was on the cluster.

I know the cluster gauge for Voltage is just a reference, but a 3-4V fluctuation seems excessive and the blower motor turning on and off is something I've never seen happen even when the main or aux battery was going bad.

Maybe its a bad new battery but can't imagine why 4-5 months of flawless operation, I now get this? I did check all connections to the battery to make sure they were tight and also pulled the IBS sensor off to try and reset it. I know that takes multiple cycles to reset with 8 plus hours of setting between ignition cycles.

12.6V is what I get using a multimeter across the battery posts while the truck is setting in the driveway. Are these vehicles that touchy when it comes to voltage? I know AGM batteries are supposed to be between 12.8 and 13.4V at rest. I only drive this vehicle an average of 20 minutes a day but its a 2021 bought in Oct of 2020 and never had an issue until late 2024. Got 4 years out of main battery and aux battery and now my new battery (4 months) and am having issues.

Going on a 4 hour ride tomorrow, so we'll see how that works and if the battery is still at 12.6V at rest when I get back.

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[Lost1wing]

I would disconnect and isolate the battery cables. Charge your battery with an AGM charger. Let it sit for 30 minutes after charging before checking the voltage with your meter. If you see 12.6vdc or less I would look at a new battery.

 

[mtudb24]

I would disconnect and isolate the battery cables. Charge your battery with an AGM charger. Let it sit for 30 minutes after charging before checking the voltage with your meter. If you see 12.6vdc or less I would look at a new battery.

Drove it 2 hours non stop twice today (4 hours total up north and back to get boat out of storage). Dash gauge still ranged from 11.9 at stop light to over 15 while driving and dash lights for Brake, Traction control, Service stability system etc all would flash for a brief nano second which varied from 5 times in 5 minutes to 2 times in 20 minutes.

Got home, truck sat for about 2 hours. For giggles went out and pulled the battery cables and measured the voltage across the battery. 12.86 is what it showed. Drove it 20 minutes to run errands and grab dinner. and voltage never ran above 13.4 and no lights on the dash nor did the blower motor stop running or Headlights flickering.

Maybe its time to build a new one HHAHAHAHAHA

 

[ShadowsPapa]

Drove it 2 hours non stop twice today (4 hours total up north and back to get boat out of storage). Dash gauge still ranged from 11.9 at stop light to over 15 while driving and dash lights for Brake, Traction control, Service stability system etc all would flash for a brief nano second which varied from 5 times in 5 minutes to 2 times in 20 minutes.

Got home, truck sat for about 2 hours. For giggles went out and pulled the battery cables and measured the voltage across the battery. 12.86 is what it showed. Drove it 20 minutes to run errands and grab dinner. and voltage never ran above 13.4 and no lights on the dash nor did the blower motor stop running or Headlights flickering.

Maybe its time to build a new one HHAHAHAHAHA

For those lurking or trying to learn -

Don't drive to charge batteries. An alternator's purpose is to supply electrical needs to a running vehicle and top off a battery after a start - NOT to charge a battery.

IF you have low battery voltage - use good, proper AGM battery charger.

 

[Lost1wing]

Drove it 2 hours non stop twice today (4 hours total up north and back to get boat out of storage). Dash gauge still ranged from 11.9 at stop light to over 15 while driving and dash lights for Brake, Traction control, Service stability system etc all would flash for a brief nano second which varied from 5 times in 5 minutes to 2 times in 20 minutes.

Got home, truck sat for about 2 hours. For giggles went out and pulled the battery cables and measured the voltage across the battery. 12.86 is what it showed. Drove it 20 minutes to run errands and grab dinner. and voltage never ran above 13.4 and no lights on the dash nor did the blower motor stop running or Headlights flickering.

Maybe its time to build a new one HHAHAHAHAHA

I think you would benefit doing an IBS reset and charging your battery to full.

 

[mtudb24]

I think you would benefit doing an IBS reset and charging your battery to full.

Drove up to the cottage this weekend (2 hours), an hour in the trip and the voltage on the gauge went to 15.3+ volts and all the traction control / brake / ABS lights came the dash for a brief nano second probably 20 times for the next hour of driving. Once it goes off once at 15+V, it will go off as low as 14.7V on the cluster. There are no drivability issues except my headlights / fog lights will flash light crazy if its dark enough for them to be on. Just lights on the cluster

Got it to the cottage and pulled the battery cables and charged it with a AGM battery charger. It was at 76% charged according the charger's digital gauge. Took about 1.5 hours to get it to 100%. Pulled the boat to the gas station and dumped it in the water at the marina (about 30 min drive). No issues.

Got up the next morning and tried to remote start the truck, and it wouldn't go (horn and lights just beeped once). Checked the voltage at the battery with a meter and said 12.7V but when i looked at the cluster voltage gauge it was 10.9V.

Taking the battery to the auto parts store I bought it from for a load test tomorrow.

What controls the voltage to the cluster? Is it the IBS sensor? Or the BCM or ???

 

[Lost1wing]

The BCM gets both battery states through CBC (can bus C) directly from the IBS. I would guess that the IP gets the voltage data from the BCM. I have not read that, just a guess.

Did you do an IBS reset? After charging your battery?

The 10.8vdc on the display is showing a voltage drop because something else is being powered. With the display showing 10.8vdc see what the Fluke says. The IBS must be seeing the 10.8vdc, that is why the pcm is commanding the higher voltage from the alternator. If the IBS reported 12.8vdc or more, you most likely would not see a charging voltage of 15vdc.

I would check all connections. Including the ground cable at the right fender ground. Just because your battery connection are tight, it is possible for the clamp to still be loose on the battery post. Give them a good twist. Double check your KC lights. You could disconnect for now until you figure this out.

Did you happen to read any codes? You can use you steering wheel controls and view on your dash with your Tazer.
ABS B- faults and flickering headlights sound like a weak battery.

 

[Lost1wing]

Drove up to the cottage this weekend (2 hours), an hour in the trip and the voltage on the gauge went to 15.3+ volts and all the traction control / brake / ABS lights came the dash for a brief nano second probably 20 times for the next hour of driving. Once it goes off once at 15+V, it will go off as low as 14.7V on the cluster. There are no drivability issues except my headlights / fog lights will flash light crazy if its dark enough for them to be on. Just lights on the cluster

Got it to the cottage and pulled the battery cables and charged it with a AGM battery charger. It was at 76% charged according the charger's digital gauge. Took about 1.5 hours to get it to 100%. Pulled the boat to the gas station and dumped it in the water at the marina (about 30 min drive). No issues.

Got up the next morning and tried to remote start the truck, and it wouldn't go (horn and lights just beeped once). Checked the voltage at the battery with a meter and said 12.7V but when i looked at the cluster voltage gauge it was 10.9V.

Taking the battery to the auto parts store I bought it from for a load test tomorrow.

What controls the voltage to the cluster? Is it the IBS sensor? Or the BCM or ???

The remote start could be some other reason, like a CEL or even a pending code. 12.7 vdc isn't terrible. If you had tried to remote start, you woke up the Jeeps electrical system causing a battery draw. If your lights also came on, thats just even more draw from the battery. 10.8vdc was showing you the voltage drop. If you were to get in, close the door and turn the lights off, your voltage should read higher.

My 5 year old batteries still read 12.2vdc on the display with the engine off. I will see what it says with the lights on.

 

[PuddleJumper]

Long story short. Bypassed my aux battery and pulled the negative cable and fuse 42 etc back in Oct / Nov 2024 when the aux battery took a dump and stalled the truck in my driveway at 9V. Then my truck went haywire and voltage on the cluster was 16+ volts and changed the main battery around Jan / Feb 2025 and upgraded to a 94R battery size. All was good after that. No issues

Yesterday, I tried to remote start the truck and it wouldn't work. Didn't think anything of it as I parked it on a angle towards the front and thought maybe I was low on gas (this has happened many times). But when I got in and manually started it, there was no low fuel light on. Then I noticed driving at dusk and all of a sudden my headlights were flickering really bad (LED's but changed to LED setting with the Tazer) and my cluster lite up for less then a half second saying service ABS multiple times. It was so fast, the cluster never gave an audible "ding". I could just see the flash of the round ABS light.
I also noticed voltage was 14.6-15.0 and coming to a stop it dropped to 11.6V and engine stuttered but then jumped right back up to 13V. I had the blower motor going (not on AC) but as the voltage on the cluster reached 14.7V or higher, the blower motor would shut off and then turn back on when the voltage went back down.

I have no additional electrical accessories besides the 3 KC's that are tied into the battery and on a toggle switch in the cab. I can't imagine anything drawing a parasitic load.

The remote start worked this morning heading into work but the blower motor was on and off depending on where the voltage was on the cluster.

I know the cluster gauge for Voltage is just a reference, but a 3-4V fluctuation seems excessive and the blower motor turning on and off is something I've never seen happen even when the main or aux battery was going bad.

Maybe its a bad new battery but can't imagine why 4-5 months of flawless operation, I now get this? I did check all connections to the battery to make sure they were tight and also pulled the IBS sensor off to try and reset it. I know that takes multiple cycles to reset with 8 plus hours of setting between ignition cycles.

12.6V is what I get using a multimeter across the battery posts while the truck is setting in the driveway. Are these vehicles that touchy when it comes to voltage? I know AGM batteries are supposed to be between 12.8 and 13.4V at rest. I only drive this vehicle an average of 20 minutes a day but its a 2021 bought in Oct of 2020 and never had an issue until late 2024. Got 4 years out of main battery and aux battery and now my new battery (4 months) and am having issues.

Going on a 4 hour ride tomorrow, so we'll see how that works and if the battery is still at 12.6V at rest when I get back.

sounds like you have an intermittent ground fault. I.E a big posi wire is grounding and driving load up, alternator steps up to catch load, posi isolates again and the alternator dumps voltage as the load disappears. I'd check and see that your AUX posi cable isn't live and banging around in there or touching its ground sibling while driving

 

[Lost1wing]

sounds like you have an intermittent ground fault. I.E a big posi wire is grounding and driving load up, alternator steps up to catch load, posi isolates again and the alternator dumps voltage as the load disappears. I'd check and see that your AUX posi cable isn't live and banging around in there or touching its ground sibling while driving

I would check this for sure. I think his battery would be totally dead or worse. He could let the smoke out of the cable insulation.

 

[ShadowsPapa]

My 5 year old batteries still read 12.2vdc on the display with the engine off. I will see what it says with the lights on.

Time to charge 'em - that's only about 50% charged! They should be in the 12.8 territory fully charged, 12.2 is as far down as I'd ever let a battery get. (even an old-school battery)


Did anyone else catch this picture?
How does a Fluke read battery voltage with ONLY the positive lead on the positive terminal of a battery?
What's the Fluke black lead connected to - and if there's nothing on that battery connecting it back to the vehicle, all terminals are removed, how do you read voltage by just holding the red lead on the positive terminal?

Take a look - there's nothing at all connected to the negative battery post - yet he's getting a reading?

 

[Lost1wing]

Time to charge 'em - that's only about 50% charged! They should be in the 12.8 territory fully charged, 12.2 is as far down as I'd ever let a battery get. (even an old-school battery)


Did anyone else catch this picture?
How does a Fluke read battery voltage with ONLY the positive lead on the positive terminal of a battery?
What's the Fluke black lead connected to - and if there's nothing on that battery connecting it back to the vehicle, all terminals are removed, how do you read voltage by just holding the red lead on the positive terminal?

Take a look - there's nothing at all connected to the negative battery post - yet he's getting a reading?

The negative probe is just out of sight. You can see part of it. Most likely he is pulling back on it with the tip just out of view.

 

[ShadowsPapa]

The negative probe is just out of sight. You can see part of it. Most likely he is pulling back on it with the tip just out of view.

It must be wedges against the negative post - otherwise I was wondering if he was some sort of magician or something.
I looked and looked and where the heck is the negative lead! How is this even possible? It's witchcraft, I tell ya!

 

[Lost1wing]

Time to charge 'em - that's only about 50% charged! They should be in the 12.8 territory fully charged, 12.2 is as far down as I'd ever let a battery get. (even an old-school battery)


Did anyone else catch this picture?
How does a Fluke read battery voltage with ONLY the positive lead on the positive terminal of a battery?
What's the Fluke black lead connected to - and if there's nothing on that battery connecting it back to the vehicle, all terminals are removed, how do you read voltage by just holding the red lead on the positive terminal?

Take a look - there's nothing at all connected to the negative battery post - yet he's getting a reading?

I had it plugged in a week ago after my trip. It had sat for over a week. This morning when I checked it was 12.2vdc. Haven't driven it since I pulled the charger off last week. That reading is from a week of sitting on 5 year old batteries. I'll probably plug it in again today when an extension cord frees up.

 

[PuddleJumper]

I would check this for sure. I think his battery would be totally dead or worse. He could let the smoke out of the cable insulation.

Depending on the battery he has it could have safeties in it. Mine has an over volt and under volt shut off. But yeah if I’m right his battery is at least on deaths doorstep

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