Voltage fluctuation are normal as they needed to squeeze another 0.001 mpg out and are using an Intelligent Battery Sensor. Dunno if yours are.

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Sounds like a PCM or intermittent circuit problem to me. The regulating circuits usually don't throw codes but can cause this kind of thing. The IBS module (at the battery end of the battery cable) can also be an issue. Usually an alternator will fail completely, but their performance can become marginal and then there is that notorious bad V6 alternator chassis ground. You may need to find a better shop.

 

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I have searched the web and find all kinds of WK2's with this problem, but no solutions. Wranglers too. Oh, NO CODES. Why the hell did they go to this 2 battery BS system? If anyone has a silver bullet to address this, please let me know. I still have, and love my '94 Wrangler, but I'm about to become a 1-Jeep family if this keeps up. Ford Explorer here I come, unless someone has some new ideas on this.

HEMI = No ESS. Just saying!

 

No need for a Hemi here in Korea, but I do love the big motors.

 

Question @ColdCase At what battery voltage does the dash gage indicate charging and what is considered normal? In an unusual instance today, same drive, same cold temp, same conditions as everyday, it never dropped below 13.5 and that was only momentarily. It hung around 13.8, 13.9 and sometimes 14.0. Bounced around a bit at times 13.5-13.7, and I go NO lights this afternoon. Also, what's the relationship between the two batts? Does the main charge the aux? What is the dash gage actually reading? Main or both?

 

I have been told that voltage can run from 12.6-14.5 and it depends on the the battery needs in regard to a charge, those that are seeing 14.4 all the time may have an issue. Otherwise it jumps around all over with what seems like no rhyme or reason. I've heard that, if not the battery or alternator, the "will be shutting down soon" message is usually a faulty PCM or corrosion in the connector, sometimes the IBS. There is often a status data recorded there that doesn't make much sense, or inconsistent live data from the IBS sensor.

There is a detailed description around here somewhere as the topic comes up often, probably in one of the ESS threads. The alternator charges both batteries. The PCM regulates the charging voltage/rates based on condition of the big battery (reported by the IBS), throttle, temperature, and couple other things. Otherwise the big battery is used only for starting, the little battery powers everything else. If the ESS battery runs down or there is an issue with it, the Jeep switches to the big battery to power everything and you get an ESS not available status.

Did you ever solve this problem? ESS and battery voltage problems

Are you sure the stop message is due to the ESS and voltage?

 

My Jeep 2020 rubicon recently started doing the same thing. I did notice though that if I turn off the automatic start before I start driving these lights never pop up. However, when I don’t turn off the automatic start then shortly through the drive, I get a battery signal and then today I even got the stop shortly the vehicle will shut off soon sign. I’m gonna take my car into the shop as well but I’m thinking about replacing the batteries first because after reading all these forms, it seems like replacing the batteries is what fixes it. I don’t know anything about cars so this is truly a shot in the dark but it doesn’t seem like a lot of people know what is causing this problem.

 

Ford explorers have this problem too. I build police vehicles for a living. Had several explorers with is same issue. Sorry can't tell you what the fix was because they went back to the dealer to get it fixed.

 

Customer of mine brought his 2018 Jeep Compass with "Stop safely" warning message and engine code P2AF5 to multiple dealers for a total of 3 months. Items were changed such as the batteries, IBS, PCM, and PCR. After hours of of cleaning all positive and negative battery cables as well as fuses, I noticed a consistent issue when the message would pop up. I turned on one of the reading lamps while sitting in the drivers seat and idling. After some time, the reading lamp would brightness would fluctuate for 2 or 3 seconds. I plugged in my scanner and recorded the vehicle module voltage live data. It happened again and after checking the data log, I noticed readings of 13v-15.7v during the 2 or 3 seconds of observing the flickering light. I purchased a new alternator installed the next day. After driving around for over an hour, the message and MIL never came back on. Customer also drove around and did not observe the problem anymore.

 

Have you ever found out what cause that to happen it’s happening to me rn ?

 

A corroded ground wire under the hood near the under-hood post, passenger side towards the back side.

 

Green tape on a positive terminal?

I put a new ground strap on my 2016. Chassis to alternator was bad.

Does this SS error mean the battery is going to die and so is the vehicle?

My voltage is between 14.3 and 14.7 most of the time. The vehicle will start up during ESS if voltage drops below 11.7 ish volts.

 

Charging voltage should not be jumping around that much, at least it never did on my 98 or 07. In fact when the PCM went bad in the 98 the first sign was the voltage meter dropping to zero & the check gauges light coming on. In my 98 it is usually 13.75-14.2, similar or a little higher for the 07. I’d be looking at all the battery terminals & grounds & all the alternator wiring. Any fault codes logged?
Lastly I think the fact that the dual battery system does not isolate the batteries with the engine off (if I am in fact right about this) is an engineering mistake plain and simple. I am familiar with battery systems in boats and that is something you never do!

 

Oh about 2014 or so FCA, like other manufactures, needed to squeeze another .1 mpg out so the they introduced smart charging. There is a couple threads around here with descriptions. But basically it charges the battery when the engine is slowing or when you are braking, and doesn't charge when you are accelerating. So its normal to see the voltage jump around a bit. One needs to be careful applying concepts of decades ago to these newer vehicles as a few no longer hold water.

 

Honestly that doesn’t make sense; alternators put out little current at idle & low revs. If that’s the case then the engineers are being told to design things that don’t work!
Take a look at the FAQs on ARCO Electrics website. They explain well the difference between battery chargers and alternators.

 

I'm just explaining how it works and how you can sometimes go down the wrong path using old school knowledge.

I think I agree that, if its purpose was to improve idling or low RPMs, then it may fail. But otherwise, when you are accelerating, you'd want engine power. Most of us also like good throttle response. So it makes quite a bit of sense to shed power hogs under those conditions. I recall disabling the alternator decades ago to get another .1 second off quarter mile times. Then connecting it back up to recharge the battery on the ride home.

Using electric hydraulic pumps for the power steering and electric cooling fans are other examples of temporarily shedding loads. I think I read somewhere there is 4-10 HP to gained, along with a bit of mpg, by using the engine to recharge the battery only when you don't need that HP. Anyway its was concept in vogue in the 50s and 60s that has now been expanded to also improve mpg.

 

I think it is a question of misplaced priorities....
There should be no interference with mission critical functions to simply improve power or efficiency.
Mission critical meaning the vehicle starts reliably and does not leave the owner stranded.
If you off road your Jeeps, having a dual battery system that is less reliable than a single battery system, is a risk.
A proper dual battery system would use 2 equal sized batteries, that can be isolated, when not charging, it is simple stuff that any boat with a lot of electronics or "house functions" like refrigeration or A/C, has. No magic, no high tech here. It does cost a bit more though. 2 AGM batteries and a Blue Seas Automatic Charging Relay.
On my old boat I have 2 GP 27 dual purpose lead acid batteries (AGM cost for these, is very high) and a simple Blue Seas #1, #2, 1+2 and OFF switch. This allows the use of either battery always leaving the other in reserve. An automatic charging relay does this with no intervention by the operator but the boat has to be wired for this, from the outset, which mine is not. So I use the manual system. If both batteries are too weak to crank the engine they can be paralleled to do so. Or if one is fine and the other needs to be charged you can start on both, run it for an hour at speed, and then go back to isolating the batteries. I also added an LED voltmeter that keeps track of the voltage reading of each battery.
Similarly, also a risk is an air suspension system, which could fail off road and leave you unable to drive out without extra tire/vehicle damage. This is why I have decided not to buy a newer Grand with this system, it has some nice features, and functionality, but is not to me worth the cost or complexity.
My priorities are simple, it has to start, get me there, and get me back. Everything else should take a back seat.
It's going to get to the point (actually we are already there) where I find nothing, I want to buy. I will have to rehab an older Jeep and set it up the way IMHO, it should be to simply, get me there and get me back.

 

I think Lou wants ELSD too

I think it is a question of misplaced priorities....

Can't do anything about misplaced priorities.

The car engine must be shut off when not moving, at stop lights for example (the governments around the world require it or you pay a tax. Jeep pays a tax on the V8). But the lights, computers, radio and ventilation use battery power. You want enough power to restart when the time comes, however long that takes. Similar to a lot of modern commercial UPS systems and generators, they chose to use two batteries, one to power the load during temporary outages and a second battery isolated by a relay for starting the generator for longer outages. The second battery is monitored as it runs down to the point it won't supply enough power and then automatically starts the engine. The engine/generator supplies AC power until the batteries are recharged, shuts down the engine and the cycle continues. After some trade off analysis the engineers determined that a big secondary battery is not needed in a car, so they saved some space and money and used a smaller one. Engineers spend a lot of time coming up with clever less costly designs so the company can survive.

There are a lot of things that can leave you stranded. Out of gas for example. A second battery that loads down the first is rare. AGM type batteries don’t short like flooded cells, and are quite reliable. It seems the manufacture of the smaller battery is having some difficulty, however. If the cars had to use flooded cell technology, it may be a different story. A hole in the boat is not as rare as a AGM battery fault and that can leave you dead in the water.

 

...Then you want the Limited X trim Grand Cherokee with the 5.7L.
No air suspension, no auto-start, dual battery nonsense.
It also comes with the hood from the SRT and nice wheels and ELSD.
The seats have the "heritage" configuration with horizontal pleats in them to match the style of old mopar muscle cars of long ago.

 

I found 2 of these one looked like a theft recovery the other had an accident record on its carfax

 

And it’s not just Jeep….i looked into Toyota and found that any of them that use the electric 4x4 actuator are prone to it not engaging. If this happens on the road the worst that will happen is you get towed. If it happens off road it’s a much bigger deal could be a VERY long walk out or very expensive tow. Again this function is more reliably performed by a simple linkage. There is no read advantage to their flimsy actuator with a thin rubber gasket plastic gears and a stepper motor & wiring. What’s in all the older Grands, every CK, YJ TJ, CJ JK and JL is superior.

 

What’s in all the older Grands, every CK, YJ TJ, CJ JK and JL is superior.

There is a couple sides to these trade offs. How would you solve the warranty claim problem/cost when a vehicle target customer is not all that mechanically inclined, not much driving skill, absent minded, but just wants superior nasty weather performance along with some trail capability at a reasonable price. These folks have a tendency to routinely forget to pull the lever and drive around all day in 4lock. The transfer case or joints break and Jeep repairs them, under warranty. In the case of the wranglers they just up the list price, folks tend to buy them regardless, but a SUV is in a much more competitive environment. In previous years, Jeep didn't have technology, but now they can offer sophisticated traction control, true 4x4 without the risk of operator error either ruining the drive train, or the lawsuits from badly using a manually controlled locker. The bean counters probably determined a model with levers would not sell enough to be profitable, and they were selling as many grands as they could build. RAMs went to a clutch based transfer case in their base light duty models, that offered 4 Low, but you couldn't lock them. They did offer a true 4x4 case with levers as a costly option but it didn't sell well. Most folks didn't want to deal with it. They also offer all the goodies in a Wrangler, at quite a price.

At least they are still offering 4WD and AWD versions in a WL and Wagoneer. But even the 4WD is now limited to higher line models. I would anticipate 4WD will not be offered in a Grand in a few years, it hasn't been offered in a Durango for quite awhile, if ever. So Jeep Grands are getting soft. The Wranglers are getting soft enough that they may be suitable for those that wanted simple 4WD in a comfortable enough road ride.

 

Look on Carmax. They should show at least one.

 

If someone blows up their transfer case because they are driving around in 4-High that's not a warrantee claim
If the transfer case fails due to clutch wear, or electronic issues, it is a warrantee claim
If learning how to use part time 4x4 is too hard for some people, they can buy a Subaru
We all used to know how to drive a standard shift, the onslaught of technology is making people less capable and less adapted to their environment. This, is not a given, or inevitable, it must be resisted.
Jeeps don't have to lower themselves down to the level of an appliance.
If they do, there are plenty of more reliable appliances around with better dealer service to boot
And then, just why buy a Jeep? There goes your market.

 

Kinda harsh? How do you tell what causes the transfer case to fail? Customers wont believe it. You did't offer a viable solution. Subarus are not SUVs that can tow or haul well enough.

So what do you do when you want to build a vehicle for the masses, because selling a massive number of vehicles is a money maker, that has superior nasty weather drivetrain ( i.e. lockers) that also won't kill them, and strong enough for a good tow rating and hauling.. That quickly leads to a drivetrain that can be software controlled that can modify the drivetrain and ground clearance configuration real time based on speed, wheel spin, steering angle, yaw... so its a safe and capable vehicle. Little driver stress, little drama. I think thats always been the product target for higher end model Grand Cherokees, and some other companies.

Today there is better technology that is better than the mechanical systems of decades ago, for the masses. Excellent systems for the time they were built. And, by chance, easier to modify for off road excursions. The current stuff is better, in 99% of situations. You can still get the levers you want, but not in a GC, its never been its market focus. Now there is arguably better design tools for the engineers, where in the past engineers had to build in large margines for error, now days they can cut it closer. Creates some durability problems as folks expect a 300,000 mile car, but the engineers are told to design to 150,000 miles. There are quite a few more constraints and design factors now days, there has always been cost and schedule.

Those that don't need 4x4 buy the base Grand Cherokee QTI transfer case. Also pretty good for an AWD. Lot of folks here have fun with them off road.

 

Yet, Jeep has no issue continuing to sell JLs and JTs with manual transfer cases as they should be. I can say that just about every SUV I have seen on the beach good & stuck ($ 500 tow unless you have a buddy) had an electronic 4x4 system. When Grands were sold with Selectrac 1993-2004 no one on the old Jeeps unlimited board complained about them and if you didn’t want to think about how to use it you had a good non electronic option; Quadra Trac in 249 & 247 versions…..
That said I was suspicious of the 245 in my WK and the only issue I ever had was the bungled recall where FCA re-programmed the 4x4 selector motor and that caused you to lose low range. Took 2 trips to the dealer to straighten that out.
Never had a problem with the 242 in the ZJ(180,000 miles) or the 241 in the Wrangler (104,000 miles).
I see people out there every summer who have no idea how 4x4 works. Bad enough on the beach what if they were out in the desert.

 

Thats my point. Jeep targets two different markets; different trade offs, different compromises.

Drivers issues on sand have more to do with tire pressure and taking the wrong line I think. Most SUVs don't have a sand traction mode.

I never had a problem on the beach with my 2WD open rear Mercury Comet either.

 

three disabled vehicles I have seen on the beach....
Liberty, electric 4x4 failed, rear tires dug in even aired down
Older Chevy Blazer same thing
Even older YJ Wrangler, the vacuum operated front axle disconnect failed, same thing. They used this on older XJs and YJs but stopped using it because of the failures. Went back to permanently locked front hubs which won't fail on you. The auto hubs on older Ford Explorers were also a headache.
Late model Cherokee, the owner wailed that it was in sand mode but she didn't air down (user error)
When you get stuck there only one tow company will come to get you and it's $500 an hr. This is on Fire Island NY, Democrat Pt and Jones Beach Island NY, Sore Thumb Beach, both have very soft sand areas, 20 psi is not aired down, 12-10 is.

The way I wound up buying Jeeps? Looked at the electric 4x4 (back in '98) in the Explorer and S-10 Blazer and thought that was a rube goldberg system destined to fail meanwhile the ZJ had the simple lever, which never fails. So that's what started me on Jeeps. Sadly, those traits are gone from current Grands, I am glad that finally the tow rating on the Wrangler has been improved to meet what I need, (5,000 lbs for the 2024 with tow package) so that will likely be my next Jeep purchase.