Codes after alt., main/auxiliary battery swap.

[outdrluvr28]

Hey gang,

so I have a 2021 JT Willys. 58k miles. Started having idle issues and the dreaded “check engine” light came on so I took it to the dealership (yuck) and had them diagnose it. They came back saying I had the dreaded P0300 multiple misfire code pop up. They kept it for a day only to call me saying it needed new plugs, new alternator and both batteries replaced.

I picked it up and did the alternator/batteries swap myself and gonna have a trusted local shop here replace the plugs.

I was excited the gladiator fired up perfectly after installs, butI now have multiple addition codes. I also get amessage the start/stop is not working, battery power is low AND a scary warning saying to park safely because the vehicle is about to shut off. Anyone ever experience this after doing the batteries and alt swap? Thanks in advance!

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[CrazyCooter]

Aux battery not fully charged? I can't tell you the number of smaller sized powersports batteries I have gotten that were DOA off the shelf
.

 

[outdrluvr28]

Aux battery not fully charged? I can't tell you the number of smaller sized powersports batteries I have gotten that were DOA off the shelf
.

It read 12.63 when sitting out and vehicle turned off with battery installed.

 

[CrazyCooter]

It read 12.63 when sitting out and vehicle turned off with battery installed.

I'd say that's 90%+ and good enough!

I so love my rig whenever I drive it, but all of the electronics give me anxiety!

 

[outdrluvr28]

I'd say that's 90%+ and good enough!

I so love my rig whenever I drive it, but all of the electronics give me anxiety!

Same here! I’ve done so much work to this rig and I miss camping. Stressing about this code issue ??‍

 

[Mr._Bill]

Clear the codes. Disconnect both batteries and the IBS (for at least 10 minutes). Fully charge each battery. Carefully put it all back together, and try again. Check the alternator and cable connections and all the cabling while you're at it.

 

[outdrluvr28]

Clear the codes. Disconnect both batteries and the IBS (for at least 10 minutes). Fully charge each battery. Carefully put it all back together, and try again. Check the alternator and cable connections and all the cabling while you're at it.

Thanks man. What is IBS? Sorry. New to all this. I’ll do what you recommend!

also, is there a way to charge the aux battery without pulling it out?

Do I quick charge or trickle charge the the batteries?

 

[Mr._Bill]

The IBS is the sensor attached to the negative post of the main battery. Pull the cable off the positive post of the main battery. Make sure it doesn't touch anything under the hood. Connect the charger to that cable and the negative terminal to charge just the Aux battery. Charge the main battery using the negative terminal and the positive post. A standard AGM charger that runs the battery through the charging cycles is best. A trickle charger is okay, it will just take a little longer.

 

[ShadowsPapa]

"Trickle chargers" don't exercise the AGM battery the way a real charger will.
When it's just a bit low and there are no other issues, it would be fine, but when there are issues, I'd use a real battery charger made for AGM batteries and nothing less.

If this picture is with the truck running, you have serious issues!
It means you've blown something like one of the high current fuses, or your alternator is crap, etc.
That's not due to a low or bad battery, that's due to a bad alternator, bad install, I'd even lean toward you having blown the high current fuse when doing the replacements.

If you didn't pull the negative cables off the main battery and separate them and keep them from touching anything, then you likely have a blown fuse. You must take them off the IBS, which sits on the main battery negative post, then take the two cables apart. Otherwise things are still hot.

This is the IBS -

but seeing that voltage tells me - you've got further issues than a low battery.

Bottom line -
Alternator is toast
or
you blew the high current fuse by not taking the cables apart, preventing them from touching anything and the hot cable touched ground, blowing the high current fuse.

I'm quite shocked that no one jumped at that 11.7 volts with the truck running. That's not an aux battery being low issue, IMO. The thing is screaming low voltage.
Even with a dead aux battery, there will be power from the main battery to keep it from reading that low. Looks like the whole truck is having to run off the batteries because the charging system isn't working.

(cooling fan circuit is part of that high current fuse)

 

[outdrluvr28]

"Trickle chargers" don't exercise the AGM battery the way a real charger will.
When it's just a bit low and there are no other issues, it would be fine, but when there are issues, I'd use a real battery charger made for AGM batteries and nothing less.

If this picture is with the truck running, you have serious issues!
It means you've blown something like one of the high current fuses, or your alternator is crap, etc.
That's not due to a low or bad battery, that's due to a bad alternator, bad install, I'd even lean toward you having blown the high current fuse when doing the replacements.

If you didn't pull the negative cables off the main battery and separate them and keep them from touching anything, then you likely have a blown fuse. You must take them off the IBS, which sits on the main battery negative post, then take the two cables apart. Otherwise things are still hot.

This is the IBS -

but seeing that voltage tells me - you've got further issues than a low battery.

Bottom line -
Alternator is toast
or
you blew the high current fuse by not taking the cables apart, preventing them from touching anything and the hot cable touched ground, blowing the high current fuse.

I'm quite shocked that no one jumped at that 11.7 volts with the truck running. That's not an aux battery being low issue, IMO. The thing is screaming low voltage.
Even with a dead aux battery, there will be power from the main battery to keep it from reading that low. Looks like the whole truck is having to run off the batteries because the charging system isn't working.

(cooling fan circuit is part of that high current fuse)

Thanks for that response, man. By high current fuse, do you mean the array that’s connected to the end of the pdc? See picture. I assume so as another member told me to check the N5 and two others which are on that array. My only hiccup is I don’t know (haven’t been able to find a how to) check those with my digital meter. I ordered a new array either way just to have a spare in case it is not the problem.

 

[outdrluvr28]

The IBS is the sensor attached to the negative post of the main battery. Pull the cable off the positive post of the main battery. Make sure it doesn't touch anything under the hood. Connect the charger to that cable and the negative terminal to charge just the Aux battery. Charge the main battery using the negative terminal and the positive post. A standard AGM charger that runs the battery through the charging cycles is best. A trickle charger is okay, it will just take a little longer.

Awesome. Thanks man

 

[outdrluvr28]

Just wanted to update- I pulled the fuse array and tested each one. Discovered the N3 is blown. Thanks everyone for your helpful replies! ??????

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