Dead Gladiator. Both batteries replaced. Still dead.

[Buckshot]

2020 Gladiator purchased new in March has 4000 miles.

Monday morning jumped in for drive to office and it was dead. Tried to jump, no luck. Towed to dealership. Update call today - both batteries dead (and tech said both are defective). Batteries replaced and truck starts and runs. But now the computer doesn’t recognize the new batteries and they are trying to solve the problem.

My question to you guys/gals - chances of BOTH batteries being defective at same time? It appears to me that maybe something else is going on.

Thoughts?

Thanks.
B.

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[ShadowsPapa]

2020 Gladiator purchased new in March has 4000 miles.

Monday morning jumped in for drive to office and it was dead. Tried to jump, no luck. Towed to dealership. Update call today - both batteries dead (and tech said both are defective). Batteries replaced and truck starts and runs. But now the computer doesn’t recognize the new batteries and they are trying to solve the problem.

My question to you guys/gals - chances of BOTH batteries being defective at same time? It appears to me that maybe something else is going on.

Thoughts?

Thanks.
B.

Happed to our 2018 Grand Cherokee. The dealership told us at the time (last fall) that they'd seen a rash of bad batteries. Both batteries replaced and life was good again. No other problems, no further problems. One battery can cause the other to fail on these.

So it happened to us, and the dealer said we weren't the only ones.

 

[Mr._Bill]

I'm curious what they mean by the computer doesn't recognize the batteries. The batteries provide voltage to the system, or they don't and it doesn't work. There is a sensor that attaches to the negative post on the primary battery, and some fuse assemblies that could have been damaged. Also, the Uconnect system can take up to 24 hours to fully recover after a reboot (both batteries disconnected).

It is also possible that they accidentally damaged the computer while changing the batteries.

 

[Buckshot]

I'm curious what they mean by the computer doesn't recognize the batteries. The batteries provide voltage to the system, or they don't and it doesn't work. There is a sensor that attaches to the negative post on the primary battery, and some fuse assemblies that could have been damaged. Also, the Uconnect system can take up to 24 hours to fully recover after a reboot (both batteries disconnected).

It is also possible that they accidentally damaged the computer while changing the batteries.

I have same question. But, I wonder if that 24 hour window to reboot is what he’s referring to.

 

[jebiruph]

I wonder if they are referring to the process of the battery sensor learning the new battery. It won't enable stop/start until knows that the main battery is charged.

 

[Deadeye]

Same happened to me last year. Replaced and no further issues.

as to the computer, justlgo for a ride. The data log probably was lost when both batteries failed. After 15 minutes and then powering off for a while, it will be good as new. It sometimes happens when both batteries are disconnected

 

[Buckshot]

Update. Tech called and said all clear and it’s ready to pick up. He explained that there are 138 data points that the computer needs to cycle thru before it recognizes the new batteries. And it normally takes 24 hours/10 miles of driving. Once the reboot is complete they can release the vehicle. I p/u tomorrow. Hopefully it was just bad batteries.

 

[Buckshot]

We’ll, Houston we have a problem.

After getting Gladiator back with two new batteries and 200 miles of driving, Jeep won’t start. Ignition button is stuck on Run. Screen says Jeep not in park (it is), wipers are moving (in off position), and a message that says Check power steering. Obviously a major electrical hiccup.

Called for tow to dealership to see what they discover this time.

we’ll see…..

 

[DanW]

We’ll, Houston we have a problem.

After getting Gladiator back with two new batteries and 200 miles of driving, Jeep won’t start. Ignition button is stuck on Run. Screen says Jeep not in park (it is), wipers are moving (in off position), and a message that says Check power steering. Obviously a major electrical hiccup.

Called for tow to dealership to see what they discover this time.

we’ll see…..

Sounds like something more than bad batteries.

One thing to do is to put your keyfob up to the starter button and press it with the keyfob. That might reset it or get it out of "run". Try it a few different ways if it doesn't work, including holding it right up next to it at different sides of the keyfob while pressing the starter.

Lots of folks ont he JL side of the forum had batteries go bad by 3 years. Mine were fine but I swapped them out anyway. I put an Odyssey pure lead AGM in for the big battery and a (not sure of brand) AGM aux battery from Advance Auto, which was the only direct replacement I could find at the time. Anyway, this combo should last a good bit longer than 3 years.

I honestly think using the ESS puts more stress on them. But I'm no expert.

 

[Buckshot]

Just tried to start and now it’s completely dead. Nothing. Just like the first time, 2 weeks ago. Back to dealer.

 

[Sorbs]

They ended up replacing my PDU in my JL when this happened to me but it may only need reprogramming the keys. It’s frustrating nonetheless.

 

[jebiruph]

Just tried to start and now it’s completely dead. Nothing. Just like the first time, 2 weeks ago. Back to dealer.

Check the voltage at N3 and compare it to the voltage of the other terminals. If it's lower, it's likely that the ESS fuse at N3 is blown, preventing both the aux battery from charging and preventing main battery power from getting to the system electronics.

If this is the case, you should be able to move the cable from N3 to N4 as a temporary fix until the fuse array can be replaced.

 

[Buckshot]

Update.

Service tech from dealership called this morning and asked what exactly it was doing before it died. I explained again. He explained that they can’t find what’s wrong. Will keep looking. Later today he texted this - “Vehicle constantly using 2 amps all the time, and draining batterys. Have to track down draw.”

So the electrical adventure continues.

 

[ShadowsPapa]

2 amps is a big draw. I'd expect they should be able to track down something that large without a lot of trouble.

 

[Buckshot]

It’s interesting, he asked me several times if I had any mods. I told him it’s bone stock. Hell it’s 4 months old with 4300 miles. As of 5pm, they are still searching.

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