Auto Start Stop and Traction Control threw a code at the same time.

[mgroeger]

Driving down the highway doing about 72mph this morning and out of nowhere I get the Auto Stop Start fault light (the letter A with a circle arrow around it) AND at the same time the ESC swervy skid mark with a Jeep warning light indicator show up on my dash.
The messages in the message center show "Service Auto Stop Start System" and "Electronic Stability Control Disabled" (or something like that).

My gut was telling me the Aux battery was on it's way out so I took both the Aux and Main batteries out of the Jeep and down to the local auto store to have them tested. The Aux bat tested "OK" but showed it needed a charge which is a red flag for those small batteries. Having gone through this on my wife's Jeep I knew the Aux battery was on it's way out and the auto store person agreed. 40k miles and 2.5 years and sadly it's not uncommon for these batteries to call it a day.
The main battery was OK too but my guess is I've got about a year to go on it, it's already been replaced 2 years ago.

So with new Aux battery in hand I think I have my solution in hand. After installing it I fire the Jeep up and... errors still there. I was shocked as I thought I had figured it out but alas I was wrong. Tried using the Tazer to clear codes and do a full reboot but the codes came right back. So back to the drawing board and I'm hoping someone may have the same problem solved.
I'm now wondering if the ESC is the culprit causing the Start Stop to throw a code... who knows. The message center says to Service Electronic Stability Control System and the Tazer is showing me the code U0432 which I will be digging into more tomorrow.

Plan on wheeling at Sand Hollow tomorrow as well even if the codes are still there

Sponsored

 

[JayD1056]

I don’t know FCAs strategy here but absolutely if ESC throws a code then start stop will fall to function. One of the key things for start stop is you have to know 100% that you are stopped before the engine can turn off. So say a wheel speed sensor is going bad. And you can’t see wheel ticks or speed. Then you don’t know for certain that you are stopped. So no ESC or TCS and no start stop.

this is a simple example and checking the code is best.

 

[mwilk012]

The stop start system does not physically exist. Everyone wants to blame the new function of their vehicle that they don’t understand, instead of looking at the typical problems cars have.

 

[four low]

That code " U0432" comes back as a ABS module detecting an incorrect CAN message from the Dynamics Sensor", what poster #2 said..

 

[Yellow Cake Kid]

ABS wheel sensor issue was my first thought.

Does your front axle engage in 4WD?

 

[MarkY3130]

I don’t know FCAs strategy here but absolutely if ESC throws a code then start stop will fall to function. One of the key things for start stop is you have to know 100% that you are stopped before the engine can turn off. So say a wheel speed sensor is going bad. And you can’t see wheel ticks or speed. Then you don’t know for certain that you are stopped. So no ESC or TCS and no start stop.

this is a simple example and checking the code is best.

After wheeling two weeks ago my steering wheel is a tiny bit off center. Didn’t notice it was off center but quickly into the 2 hour drive home the ESC light activated.

Got home and used a code reader. I forget the code, but it was steering wheel position sensor.

I haven’t recentered the wheel yet, so for the past two weeks I’ve had the ESC light on, and my ESS is still functioning.

Maybe if it’s ABS related ESS stops working but if it’s just the steering wheel it keeps working?

Dont know the answer, just pointing out how mine is behaving right at this moment.

Honestly I was surprised, but adaptive cruise is still functioning as well. I’ve had ESC issues in the past that shut off all cruise control function.

 

[Gee-pah]

I don’t know FCAs strategy here but absolutely if ESC throws a code then start stop will fall to function. One of the key things for start stop is you have to know 100% that you are stopped before the engine can turn off. So say a wheel speed sensor is going bad. And you can’t see wheel ticks or speed. Then you don’t know for certain that you are stopped. So no ESC or TCS and no start stop.

this is a simple example and checking the code is best.

Jay, what you write makes perfect sense to me--both in my understanding and the logic behind not engaging a stop start system if any condition exists that could compromise the safety of that start stop system from knowing critical things like....

if the vehicle is motionless from foot brake pressure...

That said, where I'm confused is why it would cause the Start Stop light to come on rather than simply and silently fail to engage Start Stop (ESS), as we experience say, in any of the other conditions that prevent ESS from engaging like a cold engine, or excessive turn in the steering wheel, etc.

Perhaps ESC not working is considered more drastic, and enough to permanently disengage ESS until the vehicle is looked at, and those codes expressly cleared by dealer service, or those in possession of aftermarket gear like the JL Tazer and/or Jscan.

 

[Gee-pah]

The stop start system does not physically exist. Everyone wants to blame the new function of their vehicle that they don’t understand, instead of looking at the typical problems cars have.

I respectfully am not sure what you mean by this.

I think, and clearly I could be wrong, that what you're saying is that the stop start system (ESS) is more a series of conditions that must exist before the engine will turn off as a result of the vehicle being motionless from foot brake pressure, whose logic is determined by a computer already equipped with the vehicle.

And when I say conditions, for example, I mean, "the engine isn't cold, the steering wheel isn't turned too much, the ESS battery has adequate charge," etc.

Is that correct?

 

[mgroeger]

The stop start system does not physically exist. Everyone wants to blame the new function of their vehicle that they don’t understand, instead of looking at the typical problems cars have.

While it may not be a physical system, rest assured when that AUX battery starts to fail you will have headaches as well as not even being able to start the Jeep.
I went to that system first based on past experience with our other Jeep that had a bad AUX battery and a week main battery. During that issue I got all sorts of codes and failures on the dash and the Jeep wouldn't start at one point.
I understand how that system works and based on my own experience and others on this forum it is very fair to blame it for certain problems that arise.
Turns out in this case it wasn't that system.

 

[Gee-pah]

@mgroeger Mike: It wouldn't surprise me in the least if you knew this, but FWIW, there's a flash (let me know if you wish more details) for 2018 3.6L JL's that will allow the vehicle to switch over to the main battery to attempt an engine crank if the ESS/Aux battery has issues---rather than leave you stranded.

This fix is already part of model years 2019 and beyond.

 

[mgroeger]

I don’t know FCAs strategy here but absolutely if ESC throws a code then start stop will fall to function. One of the key things for start stop is you have to know 100% that you are stopped before the engine can turn off. So say a wheel speed sensor is going bad. And you can’t see wheel ticks or speed. Then you don’t know for certain that you are stopped. So no ESC or TCS and no start stop.

this is a simple example and checking the code is best.

This sounds very logical and I'll need to dig deeper into that code and find out where to start hunting around on the Jeep. Yay, like I don't already have enough to do.

After wheeling two weeks ago my steering wheel is a tiny bit off center. Didn’t notice it was off center but quickly into the 2 hour drive home the ESC light activated.

Got home and used a code reader. I forget the code, but it was steering wheel position sensor.

I haven’t recentered the wheel yet, so for the past two weeks I’ve had the ESC light on, and my ESS is still functioning.

Maybe if it’s ABS related ESS stops working but if it’s just the steering wheel it keeps working?

Dont know the answer, just pointing out how mine is behaving right at this moment.

Honestly I was surprised, but adaptive cruise is still functioning as well. I’ve had ESC issues in the past that shut off all cruise control function.

This was one of my first thoughts as well since my wheel has been cocked pretty bad after coming up hard on a ledge BUT it has been that way for weeks.
During the AUX battery install I went ahead and recentered the steering wheel but to no avail. I've had ESC failure lights after a day of off roading in REALLY dusty conditions. We pulled the code from the Tazer and it pointed to ABS system and I knew it had to be the dirt and dust jacking with the system and sure enough after a good pressure washing... voila, error gone.

One thing I did think of was I have RCV axles up front and they shed grease out of the cup. I wonder if a blob of grease got stuck on a sensor and a simple trip to the pressure washer may do the trick.

 

[mgroeger]

@mgroeger Mike: It wouldn't surprise me in the least if you knew this, but FWIW, there's a flash (let me know if you wish more details) for 2018 3.6L JL's that will allow the vehicle to switch over to the main battery to attempt an engine crank if the ESS/Aux battery has issues---rather than leave you stranded.

This fix is already part of model years 2019 and beyond.

Wow! I was unaware of this but thanks for letting me know!!!

 

[Gee-pah]

Wow! I was unaware of this but thanks for letting me know!!!

TSB 18-092-19

 

[mgroeger]

TSB 18-092-19

That is one heck of a TSB but after reading it says nothing about the AUX battery being dead and allowing main battery to take over start up.
The biggest thing on the list that would KEEP ME from getting that TSB is the engine fan noise. I LIKE the way the engine fan sounds like a turbine jet when A/C is on Max because that means it is moving serious air over the engine, something that is VERY good IMO especially fro where we live.
I am dumbfounded by the soccer moms and mall crawlers that complained about "That's too loud." and then FCA says OK we'll turn it down... really?

 

[Gee-pah]

That is one heck of a TSB but after reading it says nothing about the AUX battery being dead and allowing main battery to take over start up.
The biggest thing on the list that would KEEP ME from getting that TSB is the engine fan noise. I LIKE the way the engine fan sounds like a turbine jet when A/C is on Max because that means it is moving serious air over the engine, something that is VERY good IMO especially fro where we live.
I am dumbfounded by the soccer moms and mall crawlers that complained about "That's too loud." and then FCA says OK we'll turn it down... really?

agreed....and yet when I (forget me) and long time poster/extremely knowledgeable Jerry @Jebiruph reported the changed behavior after this TSB (I personally tested it) I was forced to conclude this cause and effect, that maybe (or maybe not) FCA was less than forthcoming in disclosing as part of the TSB flash, because to do so implies a "problem in need of addressing."

"No problem with our ESS batteries," says FCA....none at all

if you catch my drift Mike.

As you may know, the standard startup procedure for the 3.6L JL is to isolate the ESS/Aux battery for an instant pre-engine crank to check its power.

If inadequate, prior to this TSB, and any hacks like the ones Jerry introduced, like fused jumpering of terminals T1 and T2 in the Power Distribution Center (sources available on request) you were stranded.

If adequate, the main battery was connected in parallel to the ESS/Aux battery and both provided energy to crank the engine.

With the TSB, if the initial attempt to crank fails because the ESS/Aux battery's power is inadequate, upon second attempt to cold crank, power is switch to the main battery, the ESS off light is thrown on to the dash, and ESS remains off (and this ESS off light illuminated) until the next cold crank, if any, where the ESS/Aux battery has sufficient power to pass this pre-crank test, be it as a result of charging and/or replacement, and/or rewiring to run the rig with one battery (sources available upon request).

Cheers

If the TSB isn't for you Mike, and you want to know other ways to preventatively or in response to being stranded by this, responsively deal with the issue, just me know. There are quick wiring solutions.

Sponsored