ESS - Dealer Damaged Jeep - New Main Batt - AUX Delete

[Buddy Lee]

A few more things to check that might cause your ESS light to activate. The battery monitor and the hood switch’s can trigger the fault light.

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[Some Random Guy]

Speaking to the wheel speed sensor, I’d recommend letting them do it if you have a Rubicon. I’m on my phone so hard to search. If a wheel speed sensor eats it in the trail it takes out your lockers and can lock a caliper up. I think it won’t let you disconnect your sway bar either. Mine would eat a sensor most trips out (so now I drive a Sport). Usually a long stop would clear it like yours has.

 

[Fudster]

N1 on fuse array is powered by the Aux battery through the PCR. N2 feeds the main battery positive. N3 is also connected to the PCR / Aux battery and is the power source for N1. N4 is empty, and used for a spare. N5 powers your fan 60 amp normal- 100amp tow package. The last 2 power your electric steering pump and the alternator/ starter. Fuse 42 powers the PCR which monitors current between the batteries and pulling it will remove it from the system. I did not like the ESS system so I totally removed it, including the Aux battery, PCR and all the cables. My jeep now has one battery and it works great with no lights. There are a few things to do if you decide to do that but it’s worth it in my opinion. Just be aware that you could have issues at the dealership for warranty work. I chose to have a better jeep and take my chances. I had an ESS light on as well for months and chose to remove it instead of going to the dealership and having the same issues you are.

Victor. You are knowledgeable but I see James is lost so I'm going to be nit picky.

Fuse 42, yes, powers the PCR, which when energized permits the batteries to not be connected in parallel. "Monitors" is a tricky word. I get your point--in order to monitor the ESS battery the relay has to be energized during normal crank to isolate the ESS battery for independent testing apart from the main battery.

I am sorry for being pedantic.

 

[Fudster]

Thanks for that info. I have pulled the AUX as well I am just trying to diagnose the ESS warning light to make sure I don't have more serious issues now or in the future. I already found I don't have the heavy duty fan even though I think I am supposed to. If I can get all that resolved then I may do what you did for the added reliability and simplicity.

How to diagnose the ESS warning light.

We have two ways. We could put the ESS battery back in and hook everything back up as factory, or we can trick the vehicle into thinking that is the case.

Any of the 3 options I suggested prior make the vehicle test the main battery at cold crank when it thinks it is testing the ESS battery. If I recall you passed this test. The ESS off light shut off, but returned during driving. This suggests that whatever is causing your ESS off light to turn on needs to be addressed before you are in a good place running with one battery.

 

[Buddy Lee]

Victor. You are knowledgeable but I see James is lost so I'm going to be nit picky.

Fuse 42, yes, powers the PCR, which when energizes permits the batteries to not be connected in parallel. "Monitors" is a tricky word. I get your point--in order to monitor the ESS battery the relay has to be energized during normal crank to isolate the ESS battery for independent testing apart from the main battery.

I am sorry for being pedantic.

No issues here, I appreciate your knowledge. I share my knowledge and learn just as much in these conversations. The ESS system is complex just as you stated which is why I completely removed mine. The Jeep is so much simpler to deal with once it’s removed.

 

[Fudster]

I think I have ruled out the batteries

James...friend..please..don't think. Get that new battery up to a load tester. Take everything temporarily off its negative post before you do.

That Odyssey is a great replacement battery; I have it too. And it's probably working great. But no way would you be the first person to have purchased a new defective battery.

You would not believe the crap battery makers are putting out these days.

If it turns out to be the battery you sir are buying me a beer!

 

[UncleJimmy]

A few more things to check that might cause your ESS light to activate. The battery monitor and the hood switch’s can trigger the fault light.

Thanks for the information. I did make sure the IBS was fully seated in the plug. The hood switch I think works also as remote start wouldn't work with the hood open and the other activated the warning light on the dash.

Speaking to the wheel speed sensor, I’d recommend letting them do it if you have a Rubicon.

That's still a possibility. But not sure. I could just end up with worse problems like I already have.

We have two ways. We could put the ESS battery back in and hook everything back up as factory, or we can trick the vehicle into thinking that is the case.

Any of the 3 options I suggested prior make the vehicle test the main battery at cold crank when it thinks it is testing the ESS battery. If I recall you passed this test. The ESS off light shut off, but returned during driving. This suggests that whatever is causing your ESS off light to turn on needs to be addressed before you are in a good place running with one battery.

Agreed. Process of elimination you said earlier.

I also want to bring up something else with the slight possibility it could be related:

I found this part under the floor board in the cargo area. Anyone recognize what it is or where it's from?

 

[UncleJimmy]

James...friend..please..don't think. Get that new battery up to a load tester. Take everything temporarily off its negative post before you do.

That Odyssey is a great replacement battery; I have it too. And it's probably working great. But no way would you be the first person to have purchased a new defective battery.

You would not believe the crap battery makers are putting out these days.

If it turns out to be the battery you sir are buying me a beer!

Yes sir!

 

[UncleJimmy]

Update:

The Odyssey and the Walmart main and AUX batteries all tested good at AutoZone this morning.

Also, I tried swapping the relay for the ECC. No change.

 

[UncleJimmy]

Update: I think I may have found my ESS problem! I can report the ESS now seems to be functioning properly.

I did a full detail and washed, polished and waxed my Jeep getting ready for the summer months. While gently hosing off the engine compartment I pulled the hood sensors up and re-sat them. I didn't disconnect them fully, just unclipped and put back. Well, this evening I was driving and my vehicle shut off normally. So, I suspect that the hood sensors were causing the problem. I may have a short, or maybe it's something else, but I will keep an eye on it.

I learned a lot about the ESS, battery, charging, fuses etc during this troubleshooting process so that is invaluable information. Now I have an upgraded battery, the AUX deleted and I will be carrying a spare fuse array just in case.

Thanks to all those who helped, especially @Fudster.

James

P.S. I also realized that since I drive the automatic transmission in manual mode this seems to automatically turn off ESS. I prefer to drive that way partly for fun and partly for economy as I can upshift in to 8th gear at lower speeds.

 

[Fudster]

@UncleJimmy James: thanks for coming back to the forum to give us your status, by which we all learn.

Consider "examination of the questioner's hood sensors" as added to my troubleshooting list from which to help future forum members.

 

[blnewt]

Nice to hear you may have figured out the problem and @Fudster really went above & beyond trying to detail all the ins & outs of this rather complex issue.

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