CEL Codes and Need for New Batteries

[TWP5253]

23 JLUR Diesel that started throwing codes on a regular basis. I even got De-Rated on the freeway and the jeep would only do 53mph. Those codes were the dreaded Electronic Throttle Control and Stability Control. Jeep had 16k miles and never any sign the batteries needed changing. Thankfully, the Tazer Mini was able to reset the codes but I was getting nervous and had just begun a 92 Day trip with Jeep in the trailer behind my Super C. At the one year mark, I accidentally overfilled the Def tank and the Jeep threw some codes at that time so I have been careful not to fill beyond 80% full. Maybe now that won't be a problem?
I went with the H7 Yellowtop Optima and the std. $149 small battery from O'Reilly and it has now been a week of wheeling and highway driving without a single code. I also note the charging does not fluctuate as much and I most often see 13 volts when driving. I have the Banks IDash so I can watch my voltage.

I think the battery swap at the two year mark is required for all jeeps based upon my research. Thankfully the Diesel is the easiest as the little battery is directly below the big battery and I had the H7 to begin with as I have the towing package. The Optima weighs 65lbs....it is a beast!

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[Ratbert]

It threw codes for overfilling your DEF? I hadn't heard that before. It seems like that'd be hard to do if you're filing your DEF at the pump, which IMHO is much easier as well as significantly cheaper.

Many simply bypass the aux battery to remove that pain point from the system. Whichever battery dies first will take out the other, so spending a crapload on a main with a wimpy aux might not be wise.

For the ESC code try turning your steering wheel lock to lock. If yours is like mine that'll result in an extremely crooked steering wheel. Fixing that resolved the ESC issue for me.

And, of course, do the requisite pushing in of all fuses.

 

[Heimkehr]

I think the battery swap at the two year mark is required for all jeeps based upon my research.

That will vary according to a number of factors, not least the owner's use case.

My JLU will be 4 years old in two months, and the original main battery continues to reliably crank the engine. Periodic monitoring of the voltmeter reveals nothing untoward, in terms of average charging voltage.

The separate ESS battery was overridden via this harness right after I took possession of the vehicle. I do test its functioning every six months or so, and it too restarts the engine as quickly as it should after I lift my foot off the brake pedal.

 

[THAW]

The separate ESS battery was overridden via this harness right after I took possession of the vehicle. I do test its functioning every six months or so, and it too restarts the engine as quickly as it should after I lift my foot off the brake pedal.

FYI, the starter is directly connected to the main battery terminal connector, thus the main battery is utilized in ESS starts. Your test of the Aux/ESS battery is isolated only with regard to system electronics while the engine is shut down during the stop.

 

[Heimkehr]

FYI, the starter is directly connected to the main battery terminal connector, thus the main battery is utilized in ESS starts.

Maybe I'm missing something, but what purpose does the ESS battery serve, then?
Sincere Q.

 

[THAW]

Maybe I'm missing something, but what purpose does the ESS battery serve, then?
Sincere Q.

The Aux/ESS battery, alone, powers nearly every electrical system other than EHPS (power steering) and the radiator fan during an ESS event. Otherwise, it's tied to the main battery (except for a momentary test on cold start).

 

[Old Dogger]

From what has been said on this Forum, the factory Batteries are not of high quality.

 

[Deleted User 38384]

I accidentally overfilled the Def tank and the Jeep threw some codes at that time so I have been careful not to fill beyond 80% full. Maybe now that won't be a problem?

It threw codes for overfilling your DEF? I hadn't heard that before. It seems like that'd be hard to do if you're filing your DEF at the pump, which IMHO is much easier as well as significantly cheaper.

I feel like it threw a code for something else.

I fuel up at Bucee's in Melissa, TX. I also get my DEF there from the pump.

A while back I was filling up the DEF tank, and I hit that little tab that lets it fill up on its own. Went to the other side of the vehicle and got my fuel additive container. Come back to find DEF pouring on the ground. Turns out whatever the shut-off valve on that thing was, was broken. I cleaned up the DEF on my Wrangler the best I could, and told the people inside about the mess and the broken pump.

I never got a code about overfilled DEF. I'm not even sure that's a thing

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