Yet another ESS thread - not a battery issue

[TravelingJeff]

Ok folks, I'm stumped. 2022 Sahara here, and I've read every single thread I can find about the ESS issues.

We had a fully factory battery setup while we were wintering in Arizona, and the cold knocked out our batteries. Came out to a dead car that wouldn't start. Put it on a charger, was able to get everything running again, but would come out to a dead car about every third day.

This is my first thing where I think things get weird. My Avengers light does NOT come on right away. In fact, for the first 30 minutes or so, ESS functions properly, but after about 30 minutes of driving, the light comes on and it no longer works. If I put it in park, turn if off, turn it back on, then ESS functions fine for about another 30 minutes until the light comes on.

After reading on here, determined it was most likely the Aux battery. Took it to the dealer and they confirmed the AUX was bad, replaced it, and said my main tested fine but was low, so they put it on the charger for me.

ABSOLUTELY NO CHANGE. Everything seemed fine, but after about 30 minutes, boom avengers light. At this point, I decided to do some of my own investigations before going back to the dealer.

I pulled fuse F42 and disconnected the negative wire leading to my aux battery and wrapped up with electrical tape in order to isolate the aux battery from the system. My voltage while driving would NEVER drop out of the 14's, and the avengers light would still come on somewhere around 30 minutes into a drive. This led me to believe my main battery was actually bad, so I replaced it with a DH7 Optima yellow top. As soon as I replaced it, my voltage would start in the 13's, and settle in between 12.4 and 12.9 while driving, so I thought I had FINALLY figured it out.

Then the light came on around 30 minutes in AGAIN, and has continued to do so on all drives. I verified that all of my N fuses were good with my multimeter, and my alternator is smart charging my (only) battery, and F42 is removed, so no checking on the aux battery which is now disconnected.

Is anyone aware of ANYTHING else that could cause this light to come on only after you've been driving for a while? Around the time this started happening, I did have my hood replaced with a rubicon hood. Could something be happening with my hood sensors? They never say the hood is open, but it's the only other thing I can think of at this point.

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[Bob Burd]

Sounds like you have a large parasitic drain. If you have a multimeter with current measurement, that's where I would go next.

 

[Reinen]

I 2nd the parasitic drain. Try to track that down. Is anything plugged into the rear 12v outlet? Thats always on.

You should also replace both Main and Aux at the same time or you will significantly shorten the life of the one replaced battery. They are linked 99% of the time so they should be considered a single battery pair.

 

[VKSheridan]

With the auxiliary battery removed (or at least totally disconnected), running a new Optima and Fuse 42 pulled, has your Jeep been dead or needing a jump start since?

If the answer is yes, I’d be looking for a self-discharging alternator, winch, aftermarket accessory or an ECM sucking juice and putting my ammeter to work.

If the “Avenger Light” that you refer is the lil’ auto start indicator (“A” with a round arrow) AND NOT the “ESS Not Ready” statement in the EVIC, hit the button to turn it off, get a tazer lite and program it off or buy an AUTOSTOP ELIMINATOR.

If the “ESS Not Ready” is your annoyance, look to the lower rear of the R/H wheel well for a multi-pin connector. Disconnect it, spray the pins and sockets with electrical solvent and reconnect. If you have dielectric grease, put some on the connector sealing face to ensure best protection.

There’s a TIB out in the world on that critter that identifies any resistance will misrepresent the state of charge of the batteries (even if the auxiliary battery is totally removed and sitting on your workbench) and the PCM logic translates that as ESS Not Ready.

Please share your findings. We’re all getting good at this for the wrong reasons…..LOL

 

[Jebiruph]

It could be a bad battery sensor, but when the error light turns on while you are driving, it can also be from ESS being disabled because of an issue with the engine. ESS can get disabled before an engine issue hits the threshold that turns on the check engine light.

 

[TravelingJeff]

Sounds like you have a large parasitic drain. If you have a multimeter with current measurement, that's where I would go next.

How can I use a multimeter to find the source of a parasitic drain?

I 2nd the parasitic drain. Try to track that down. Is anything plugged into the rear 12v outlet? Thats always on.

You should also replace both Main and Aux at the same time or you will significantly shorten the life of the one replaced battery. They are linked 99% of the time so they should be considered a single battery pair.

Any tips for tracking it down? Nothing plugged into any of the outlets with the exception of a USB cable for my phone in the front seat, but no phone connected when I'm not in the Jeep. I also have the AUX battery totally removed b/c of the reason you stated.

With the auxiliary battery removed (or at least totally disconnected), running a new Optima and Fuse 42 pulled, has your Jeep been dead or needing a jump start since?

If the answer is yes, I’d be looking for a self-discharging alternator, winch, aftermarket accessory or an ECM sucking juice and putting my ammeter to work.

If the “Avenger Light” that you refer is the lil’ auto start indicator (“A” with a round arrow) AND NOT the “ESS Not Ready” statement in the EVIC, hit the button to turn it off, get a tazer lite and program it off or buy an AUTOSTOP ELIMINATOR.

If the “ESS Not Ready” is your annoyance, look to the lower rear of the R/H wheel well for a multi-pin connector. Disconnect it, spray the pins and sockets with electrical solvent and reconnect. If you have dielectric grease, put some on the connector sealing face to ensure best protection.

There’s a TIB out in the world on that critter that identifies any resistance will misrepresent the state of charge of the batteries (even if the auxiliary battery is totally removed and sitting on your workbench) and the PCM logic translates that as ESS Not Ready.

Please share your findings. We’re all getting good at this for the wrong reasons…..LOL

No it has not totally died or needed a jump since I did all of those things. No winch, and my only aftermarket accessories that draw power would be my headlights, taillights, and bumper mounted off-road lights wired into the factory aux switches.

I am NOT getting the "Ess Not Ready", I AM getting the A with a round arrow. This is my annoyance. ESS works fine for the first 30 minutes of a trip until this light comes on. Pressing the button to turn off ESS manually does not prevent the auto start indicator from coming on about 30 minutes into my drive. I have a Taser, but removed it for troubleshooting this, and don't think it would help considering all it does is "press the button", and the light still comes on whether I turn ESS on or off.

It could be a bad battery sensor, but when the error light turns on while you are driving, it can also from ESS being disabled because of an issue with the engine. ESS can get disabled before an engine issue hits the threshold that turns on the check engine light.

Any advice for how I can tell if something else is wrong with the motor if I have no codes? This is a brand new stock 2022.

 

[VKSheridan]

To check for draw, disconnect everything from the B+ terminal. Put one lead of your ammeter on the battery B+ and the other lead to each isolated wire. The wire pulling the amperage is your parasitic load. Keep in mind, *light* draw is normal for your radio to remember stations, remote start/unlock functionality, UConnect broadcasts etc. Once you’ve identified the hungry wire, refer to the schematic to try to determine who’s living at the feed trough.

 

[TravelingJeff]

To check for draw, disconnect everything from the B+ terminal. Put one lead of your ammeter on the battery B+ and the other lead to each isolated wire. The wire pulling the amperage is your parasitic load. Keep in mind, *light* draw is normal for your radio to remember stations, remote start/unlock functionality, UConnect broadcasts etc. Once you’ve identified the hungry wire, refer to the schematic to try to determine who’s living at the feed trough.

Thanks! I'll spend some time on this and report back.

 

[UncleJimmy]

You tagged me in the other post, here's my response:

I had the same issues, A light would come on sometimes after driving for a while sometimes right away.

Deleting the AUX did not solve it. Dealer thought it was a wheel sensor. They replaced and did not fix the issue.

Found it accidentally while washing/detailing my car. It was one of the hood sensors. You can try cleaning/lubricating maybe (dirt gets in there) or do what I did which is to switch/swap the two hood sensors. Took care of the problem. I still use ESS occasionally with the single H7 battery. No problems so far.

As a side note, the BMS resets itself every time you disconnect the battery and is normal for the voltage to stay at 14v for a few trips. Afterwords, since this is a "smart alternator" system it should fluctuate depending on charge, engine load etc. Basically it usually charges more when you are costing to a stop to save fuel.

Good luck and nice Jeep.

 

[TravelingJeff]

Thank you sir! When you say you "swapped" them, can you elaborate? Do you have any pics? I am familiar with the two plungers, are you saying they can be removed from their position independently, and then reinstalled into the other's original position?

 

[The Last Cowboy]

If you swapped the batteries from the top, pull the PDC again and carefully check all the connector pins. Sounds like you may have bent one.

I you find a bent one, straighten it with sone needle nose pliers, then slowly and carefully reassemble the PDC.

 

[Steph1]

Before removing the hood ‘’plungers’’, just lubricate them with wd-40 to make sure they move up and down smoothly, and while you’re playing with them, make sure they are connected nice and tight. I’d even disconnect them and spray wd-40 there too.

 

[UncleJimmy]

Thank you sir! When you say you "swapped" them, can you elaborate? Do you have any pics? I am familiar with the two plungers, are you saying they can be removed from their position independently, and then reinstalled into the other's original position?

Yes, the two plungers. Just disconnect and switch takes about 30 secs. That's what I did. You can also try cleaning or lubricating the sensors - I sprayed a lubricant and it worked for a couple days, or replace with new sensor - all the same idea.

 

[TravelingJeff]

If you swapped the batteries from the top, pull the PDC again and carefully check all the connector pins. Sounds like you may have bent one.

I you find a bent one, straighten it with sone needle nose pliers, then slowly and carefully reassemble the PDC.

I did not replace the bottom battery, only the top. I'm not sure what the "PDC" is. I only replaced the top battery by disconnecting the old one, and re-connecting the new one, so I'm not sure what I could have bent. Do you have any pictures of what you are referring to, or would this not apply based on my reply?

Yes, the two plungers. Just disconnect and switch takes about 30 secs. That's what I did. You can also try cleaning or lubricating the sensors - I sprayed a lubricant and it worked for a couple days, or replace with new sensor - all the same idea.

Ah, so you're saying just swap the harnesses and not the positions of the plungers themselves? I noticed one of my plungers is "taller" than the other. They are nice and snug, and do slide easily as this is still a fairly new vehicle. Less than a year old and less than 15k miles

 

[The Last Cowboy]

I did not replace the bottom battery, only the top. I'm not sure what the "PDC" is. I only replaced the top battery by disconnecting the old one, and re-connecting the new one, so I'm not sure what I could have bent. Do you have any pictures of what you are referring to, or would this not apply based on my reply?

The PDC (Power Distribution Center) is the fuse box, found under the hood between the main battery and the firewall. Since the dealer swapped the aux (or said they did) there could still be a bent pin in there if they did it from the top. You can either take it back to the dealer and see if they can fix it, or check for the issue and fix it yourself, depending on your skill and confidence level. It's not that hard, but a mistake could mean a blown N1-N7 fuse array or further damage.

It's also possible that when you replaced the main battery that you did not reconnect the BMS (Battery Maintance Sensor) or that you crossed or failed to connect one of the grounds.

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