Wolf Island Diver
Well-Known Member
First, I have no issues with ESS. For some people it’s a political issue (seems like everything is now ?) I have no political hangup with it. Statistically, over time, it does save fuel. I used it on this truck until my batteries died. The start/stops on the Gladiator are less intrusive than other vehicles I’ve driven which is odd since it’s a diesel. I did noticed that the frequency with which mine worked started decreasing within a few months of ownership, I.e., frequency of “ESS not available” messages increased.
When my batteries died the only symptoms I was having was a week or so of ESS not available messages even after driving for a while and Aux buttons temporarily not available message on startup. The aux switches would become available within a few minutes of running the alternator. When the truck died no starter pack would start the truck. The main battery had started the truck the night before with no issues.
The point is, in my case the system seemed to come off peak performance soon after taking delivery, and muddled through for about a year before dying very suddenly. When the batteries “died” the ECU went nuts. My windshield wipers came on and wouldn’t turn off. Various lights were flashing randomly. Uconnect got into a reboot loop. The DEF recirculation cycle kept starting. Despite all of the these things running and using power, the key Fob wouldn’t work. I disconnected the batteries because my wiper blades were shredding themselves.
The AUX battery was dead and the main battery wouldn’t hold a charge to the extent that it failed their testing.
This is what the service director of my dealership told me after the truck was flat bedded over there. This is a large FCA dealership in Hampton Roads with 2 Jeep-only locations.
Here’s my theory on this: The opinions on mixing dissimilar size and amp hour batteries in parallel varies. Some places, Optima for example, say don’t do it. Others say it doesn’t matter. I did zero practical work with batteries and little of the physics math on battery chemistry taking EE classes years ago. However what little I know and what I’ve read is that at least in theory mixing dissimilar batteries could affect their performance and longevity over the long term. dissimilarly sized dual batteries is suboptimal.
I think this issue with these vehicles is a function of cheap OEM batteries of different sizes and probably issues with how the system is designed. That being said, if you keep your truck on a tender, use better quality batteries, replace them at the first sign of trouble, etc., you probably won’t have an issue. But if anyone thinks they’re getting their batteries replaced under warranty at the first sign of warning messages every few years, they’re probably dreaming.
Personally I’d rather just use a single good quality (and larger) battery and not use ESS on this vehicle. When my batteries died I wasn’t oblivious to the issue. I had talked to the dealership a week prior. They told me that if the Aux switches came back almost immediately, the main battery would most likely pass testing and not be warrantied. My service writer recommended I wait a few more days before bringing it in. In other words, wait until it gets worse. Worse for me was dead. Maybe that’s just stupid advice from a service writer, but I’ve learned some inside info about how FCA has changed the way they handle warranty work and as you can guess, it’s not more consumer friendly. Dealerships no longer apply any ECU TSB unless you ask them or it’s related to symptoms you’re experiencing. This is because FCA won’t pay for it. Warranty coverage is a constant fight now. The night before my batteries died, it was below freezing. Had the DEF heater failed due to lack of power, this would have been a much bigger problem than two batteries and an ECU reflash. The liability with this system isn’t worth it to me.
When my batteries died the only symptoms I was having was a week or so of ESS not available messages even after driving for a while and Aux buttons temporarily not available message on startup. The aux switches would become available within a few minutes of running the alternator. When the truck died no starter pack would start the truck. The main battery had started the truck the night before with no issues.
The point is, in my case the system seemed to come off peak performance soon after taking delivery, and muddled through for about a year before dying very suddenly. When the batteries “died” the ECU went nuts. My windshield wipers came on and wouldn’t turn off. Various lights were flashing randomly. Uconnect got into a reboot loop. The DEF recirculation cycle kept starting. Despite all of the these things running and using power, the key Fob wouldn’t work. I disconnected the batteries because my wiper blades were shredding themselves.
The AUX battery was dead and the main battery wouldn’t hold a charge to the extent that it failed their testing.
This is what the service director of my dealership told me after the truck was flat bedded over there. This is a large FCA dealership in Hampton Roads with 2 Jeep-only locations.
- The ESS system on the Jeeps is the most common issue they deal with on a daily basis. They keep tons of batteries in stock just for this
- All the craziness I saw with the lights and wipers is normal when this happens
- They’ve seen these failures damage various ECMs
- The failure will require a series of dealership reboots, an ECU diagnostic and possible ECU reflash.
- There’s been several TSBs on the system with ECU updates and the ESS system itself has had issues fleet-wide
- The dealership has seen just about every permutation of failure including complete battery failure with no warning.
- In the service directors opinion, in the opinion of the room of service writers I asked and the technicians I asked, the system is a major liability and will leave you stranded. He recommends I remove or at least disconnect the Aux battery and disable ESS and that their dealership at least will never deny a warranty for disconnecting this system or using a Tazer to do so even if they have to lie to FCA. They absolutely hate the system and the dual batteries because of the constant stream of warranty and out of warranty work it requires.
Here’s my theory on this: The opinions on mixing dissimilar size and amp hour batteries in parallel varies. Some places, Optima for example, say don’t do it. Others say it doesn’t matter. I did zero practical work with batteries and little of the physics math on battery chemistry taking EE classes years ago. However what little I know and what I’ve read is that at least in theory mixing dissimilar batteries could affect their performance and longevity over the long term. dissimilarly sized dual batteries is suboptimal.
I think this issue with these vehicles is a function of cheap OEM batteries of different sizes and probably issues with how the system is designed. That being said, if you keep your truck on a tender, use better quality batteries, replace them at the first sign of trouble, etc., you probably won’t have an issue. But if anyone thinks they’re getting their batteries replaced under warranty at the first sign of warning messages every few years, they’re probably dreaming.
Personally I’d rather just use a single good quality (and larger) battery and not use ESS on this vehicle. When my batteries died I wasn’t oblivious to the issue. I had talked to the dealership a week prior. They told me that if the Aux switches came back almost immediately, the main battery would most likely pass testing and not be warrantied. My service writer recommended I wait a few more days before bringing it in. In other words, wait until it gets worse. Worse for me was dead. Maybe that’s just stupid advice from a service writer, but I’ve learned some inside info about how FCA has changed the way they handle warranty work and as you can guess, it’s not more consumer friendly. Dealerships no longer apply any ECU TSB unless you ask them or it’s related to symptoms you’re experiencing. This is because FCA won’t pay for it. Warranty coverage is a constant fight now. The night before my batteries died, it was below freezing. Had the DEF heater failed due to lack of power, this would have been a much bigger problem than two batteries and an ECU reflash. The liability with this system isn’t worth it to me.
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