Auto Start-Stop ESS Invert Modification

Wisconsin Mike · Jan 2, 2016

I can't say that I hate the Auto Start-Stop engine feature on my Jeep; but I can't say I love it, either. I really just wish its function was inverted. In other words, default to not shutting the engine off and let me toggle it on when I think it would be beneficial. So after wrapping up my headlight mods last week, I've been thinking about how to make it work like I want.

So today I "fixed it". I modified my Jeep so that when I start it, the Auto Start-Stop ESS function defaults to off. At any time I can hit the button and toggle it back to on. Although not a difficult modification, you'll need a little soldering skill to be able to do this. If you're not handy with an iron, you either need to find somebody who is, or just skip this mod.

The basic idea of what I did was to simply install a solid state time delay relay configured for a single pulse output to drive a small dry contact relay that has its open contacts soldered between the dash pushbutton switch contacts. I tapped into the back of the Jeep dash power plug to power the time delay relay. I configured the time delay relay so that upon the application of power, it waits 1 second, then pulses its output on for just a moment, then back off again. It resets when power is removed.

It's really a slick tiny little relay that I picked up here:
http://www.amzn.com/gp/product/B00PD65UGA

You can see in the picture that I have the two configuration lines and the optional trigger line heat-shrunk off because at this stage, I had already configured it. That only leaves power in, ground, and switched output wires to hook up.

Wisconsin Mike · Jan 2, 2016

Ideally switched ignition power (only on when the engine is actually running) would have been the preferred power source to use. I spent a fair amount of time looking for such a power source, but wasn't able to find anything in the cab. So I decided to just use the switched accessory line from the back of the power plug. That accessory line also switches off during engine cranking, so even if you're sitting there listening to the radio with the car off and then decide to start it, the ESS is still toggled off correctly.

First I needed to tap into the power at the "cigarette lighter" power port. First, you have to remove the small rectangular piece of dash trim immediately above the console piece. It just pulls straight toward the back of the Jeep. I used a hook to get behind it and pull it out. Next, I reached my fingers into the gearshift boot and pulled the surrounding console straight up. It's only held in by a bunch of plastic latches. I was able to pop the gearshift pleather boot off of the console and lift the console over the boot to get access to the accessory socket to tap into the power and ground wires.

The next task is getting to the back of the Auto Start-Stop button. This is actually pretty simple. Just follow the face of the HVAC control panel as it curves away under the dash lip and find the bottom edge. Cram as many fingertips as you can into that thin lip and pull it straight rearward. The bottom two plastic latches will pop out. Then run your fingers along the sides of the HVAC control panel up as high as you can and pull the top two plastic latches out. Four latches and that whole panel comes right out. There's a 4-Pin connector to unplug and you can carry that panel into the house to work on.

A handful of Torx T-10 screws and two latches and the back of the HVAC panel will come right off exposing the circuit board. I was happy to see a whole bunch of in-circuit test pads all over the back of this board. Close inspection with an eye loupe shows that they tested this PCB on a bed-of-nails test stand because almost every one of the test pads has a tiny pin prick in the middle of it. Anyway, I found the rubber conductive membrane switch contacts for the ESS feature and discovered that one side of that switch is ground and the other gets grounded to toggle the switch. Further, the non-grounded side of that switch has a via nearby that routes the switch trace to the back side of the board and onto a test pad. This is perfect. I don't want to solder onto a via because of the rubber membrane on the board, but the test pad will work nicely.

Wisconsin Mike · Jan 2, 2016

A small gauge mod-wire on the test pad and a bigger 24Ga wire on the ground plane wired over to an electromechanical 12V mini relay and this part is done. The solid state time delay relay will toggle this mechanical relay.

I attached the white electromechanical relay to the PCB using double sided tape in an area where the back cover won't interfere (it has some webbing molded in to support the PCB). I knotted the relay power wires to act as a strain relief and covered them in sleeving and ran them through an existing hole in the back cover.

Finally, I programmed the time delay relay following the instructions from their website so that it waits 1 second and then pulses its output on for maybe a quarter of a second, then shuts it back off. That pulse drives the mechanical relay to simulate pushing the button. Further, if I wanted, I could even add a switch to this setup to break the connection between the solid state relay and the mechanical relay so that it would default back to "normally enabled ESS" operation. For now I'm going to drive with it like this to see how I like it.

jeff215267 · Jan 2, 2016

mine is bypassed but the only problem is that the yellow autostart light is on on the dash

ptram · Jan 2, 2016

You must be an electrical engineer as that is way over my head. FCA could have made those to invert to the option to turn on instead of turn off, but probably did it the way they did to get the 1 mpg more gas mileage to satisfy our government. I am glad you were able to do that, but I always am concerned about making any factory changes as FCA now might say any electrical problem you have is yours since you modified the original factory wiring even if the electrical problem is far removed from your wiring change. Congrats though on being able to make the change---i will just keep pushing the button to turn mine off the first time it dies on me usually.:laugh:

monkeyboy · Jan 2, 2016

Mike - are you the Q guy from the James Bond movies?! :grin:

Nice work and write up... but I am with @ptram on this one. And honestly, I kinda like the ESS (most of the time...).

enki · Jan 2, 2016

I'm growing somewhat accustomed to the ESS system, but my biggest pet peeve is how, when parking the car (in my garage for instance), the car will shut off and then start right back up when I put it in park. That, to me, seems like a complete waste. If I shift right into park, I would be happy if it would just stay in 'stop' mode so I can turn the car off. I guess I can just feather the brake more so it doesn't go into effect, but I always forget and then it goes on-off-on-off.

I'm a bit reluctant to make the change outlined here. Awesome work, but my lack of soldering skills and fear of violating the warranty will also likely make me just push the button.

rpasetto · Jan 18, 2016

enki said:
I'm growing somewhat accustomed to the ESS system, but my biggest pet peeve is how, when parking the car (in my garage for instance), the car will shut off and then start right back up when I put it in park. That, to me, seems like a complete waste. If I shift right into park, I would be happy if it would just stay in 'stop' mode so I can turn the car off. I guess I can just feather the brake more so it doesn't go into effect, but I always forget and then it goes on-off-on-off....

I've maintained that this "feature" is in fact a design flaw in the stop-start system. Best response from dealer is that it "has" to work that way.... because that's the way it is supposed to work.

mowcowbell · Jan 2, 2016

Great work and illustrations of what you did. Definitely over my head and level of expertise.

I just wish there was a software fix that would invert the operation of the ESS button.

Wisconsin Mike · Jan 2, 2016

I discovered today that the accessory power port switches off during engine cranking, so this modification even works if you've shut the Jeep off and stayed in it for a while listening to the radio and then decide to start it up again. (The "wife is running into the store quick to pick up a gallon of milk" possibility.) I edited my 2nd post above to reflect that. Originally I thought that the power port stayed alive during cranking. My dashcam must just ride through that brief of an outage. Pretty happy with how it works so far.

Wisconsin Mike · Jan 2, 2016

I agree that making modifications to a car still under warranty can be scary. I was careful when doing this not to drill any holes or make any permanent changes. I even routed the wiring to the left side of the console along the existing factory wiring so that if somebody pops the right side off to change the cabin filter there would be no signs. Also, this modification would be very easy to undo in the event of any electrical problems.

If the HVAC control panel needed to be replaced for some reason, the quickest thing would be to just pull the panel, cut the wires flush at the back of the panel (everyone carries wire cutters with them at all times, right?), push the ends back into the hole, and pop the panel back in. I cannot even imagine the dealer would waste any time looking at this panel; they'd just replace it. Given more time, I would just unsolder the two wires and wick the pads clean.

Also, I know that I'm going to want more switched accessories in the future, so I wired the accessory power outlet to a pair of Wago toolless lever operated spring terminal blocks. These:
http://www.amzn.com/gp/product/B003K124UA
These lever nuts make it super easy to un-wire or re-wire anything in the future and will not vibrate loose (unlike screw terminals). I've used these for years in various applications and they've never let me down. Nothing beats solder-and-shrink, but these lever nuts make it easy to modify or undo what you've done.

ptram · Jan 3, 2016

You are very knowledgeable so you will probably have no problems. I was over at my service department today and asked about making mods like you made and the head tech said that "yes" FCA could refuse to repair some other problems electrical, but he acted like it was not likely they would. I think it would come down to the dealer you went too and if they wanted to just get out of doing work. My service department does not operate that way--probably would take care of customers if FCA didn't stop them. Anyhow, congrats on your mods and that they are doing what you want them to dol

Wisconsin Mike · Jan 2, 2016

@jeff215267 - I'll bite... How did you disable your ESS? I tried the hood switch, but my Jeep would ding and display a "hood open" error the first time I went over about 25MPH. Every time I started it. Really annoying. And it would always display the yellow auto start-stop error in the lower right corner.

Desoto · Jan 3, 2016

Should a problem arise with the IPC or BCM that requires a Star Case, It's all about how the Tech submits the form. There is a query about Customer Modifications. When "yes" is selected, it wants details. Bean Counters step in and claim denied. It depends on the Dealer and where they are with Warranty numbers that are compared within there region. I don't have any ESS equipped in my fleet, but if I did it would be a interesting challenge.

jeff215267 · Jan 5, 2016

I had a breathalyzer installed and the mechanic disabled it just the a in the dash is illuminated.

Wisconsin Mike · Jan 12, 2016

It's been over a week since I've done this mod and thus far I'm really happy with it. It works every time and I can't help but smile a little when I glance down and see that little amber LED lit up inside of the ESS defeat button.

I thought that the hardest part of this mod was getting to the back of the accessory power port in the center console to get switched power. The switched power wire for that accessory port runs to the left side of the console and ends up inside a bundle of wires right behind the removable kick panel that is right next to the gas pedal. In hindsight, it would have been much easier to just pop that panel out and then find the larger gauge pink with yellow stripe wire in that bundle and tap in there.
A friend told me about these "Posi-Tap" connectors made for just such a purpose:
http://www.amzn.com/dp/B00389RUEO

I've never tried them myself, but he swears by 'em.

Array · Jan 18, 2016

I believe the root cause is the design of the ZF 9-speed transmission to auto-start very quickly. When ESS auto stops the engine, the transmission is still in 1st gear; ready to go.

"The 9-speed automatic transmission is also start-stop capable without hydraulic impulse oil storage (HIS). Since, in the case of restarting, it is only one friction shift element that needs to be closed, response times are indeed highly spontaneous."
http://www.car-engineer.com/the-zf-9hp-automatic-transmission-at-a-glance/

As the owner's manual states, moving the shifter out of Drive terminates ESS.

Conditions That Will Cause The Engine To Start Automatically While In Autostop Mode:
• The transmission selector is moved out of DRIVE.
etc......

When we think about it, when ESS is activated, the transmission is in 1st gear and applicable clutches (A, D, and F - http://www.wk2jeeps.com/Misc/Cherokee/KL_TSB/KL_RC_R01_15a.pdf) are engaged for a quick launch in 1st. Then the driver moves the selector to Neutral which requires Dog Clutch A to be released. That requires the engine be restarted to execute that dog clutch release.

That's my cut at it. I'd highly appreciate a Chrysler engineer familiar with the system to confirm or correct.

rpasetto · Jan 19, 2016

The "requires the engine be restarted to execute that dog clutch release" condition, see earlier post#23 by Array, may be the explanation for the restart. Dog clutch A has to release to go into neutral, and evidently the restart in ESS is used as the way to do this. Whether this is because of a mechanical condition, required to have the necessary oil pressure to do the shift, an electric condition required to energize relays, or something else, this results in an undesirable result, specifically the unnecessary restart which certainly is a negative for engine wear, fuel economy and emissions. This is why I maintain that it is a design flaw. Whether this neutral shift could be accomplished by a mod to the ZF-9 trans design or whether a different trans design would be required to make these shifts with a restart, perhaps the right FCA engineer could answer.

Hopefully it is clear why the "ESS can't predict..." statement has nothing to do with the restart issue. That is the kind of thing I hear dealer service dept will say to out customers off.

Rojhan · Jan 19, 2016

rpasetto said:
The "requires the engine be restarted to execute that dog clutch release" condition

That makes sense from a mechanical viewpoint, but it sure is annoying from an operational viewpoint.

It sounds like having a human hitting the "A" button is the only workable solution.

Let's see.... splice into the button or one of the sensors (like the hood closed) that disables ESS.... Feed into a microcontroller that has GPS. Add various "geofence" locations, like your home and office, where ESS will automatically disable....

The other thing that might work would be to delay ESS/engine-off by 5-10 seconds. It defeats the purpose, to an extent, but would "fix" the issue as well as short red lights, etc. You'd need to find the actual output from ESS activation and put a delay on the leading edge of the waveform...

Having a full schematic, functional diagram, and theory of operation could make for some interesting modifications...

mowcowbell · Jan 19, 2016

I think the ESS function should be tied to the price of gasoline. When gasoline is below $1.50 a gallon (like it is here now), ESS is always off!

rpasetto · Jan 20, 2016

Do not assume that ESS saves fuel all the time. It may when in traffic with long red lights, or under EPA test conditions... for sure not when driving in the country where the only stops are brief ones at stop signs.

akguppy · Jan 21, 2016

Bingo! ^^ Or in parking lots.

rpasetto · Jan 21, 2016

or just tap the stop/start button.

crh8705 · Jan 22, 2016

Have you noticed that ESS is disabled when the low fuel light is on? This would lead me to believe it doesn't save gas.

gravitywell · Jan 22, 2016

It's more about emissions, than saving fuel.

Desoto · Jan 24, 2016

One of the qualifiers for ESS is that "Flex Fuel Adapt" must be active. I don't have any ESS vehicles to play with, but if your not using E85 it just might disable the whole thing if disabled.

Chuck1026 · Mar 16, 2016

Wisconsin Mike said:
Ideally switched ignition power (only on when the engine is actually running) would have been the preferred power source to use. I spent a fair amount of time looking for such a power source, but wasn't able to find anything in the cab. So I decided to just use the switched accessory line from the back of the power plug. That accessory line also switches off during engine cranking, so even if you're sitting there listening to the radio with the car off and then decide to start it, the ESS is still toggled off correctly.

First I needed to tap into the power at the "cigarette lighter" power port. First, you have to remove the small rectangular piece of dash trim immediately above the console piece. It just pulls straight toward the back of the Jeep. I used a hook to get behind it and pull it out. Next, I reached my fingers into the gearshift boot and pulled the surrounding console straight up. It's only held in by a bunch of plastic latches. I was able to pop the gearshift pleather boot off of the console and lift the console over the boot to get access to the accessory socket to tap into the power and ground wires.

The next task is getting to the back of the Auto Start-Stop button. This is actually pretty simple. Just follow the face of the HVAC control panel as it curves away under the dash lip and find the bottom edge. Cram as many fingertips as you can into that thin lip and pull it straight rearward. The bottom two plastic latches will pop out. Then run your fingers along the sides of the HVAC control panel up as high as you can and pull the top two plastic latches out. Four latches and that whole panel comes right out. There's a 4-Pin connector to unplug and you can carry that panel into the house to work on.

A handful of Torx T-10 screws and two latches and the back of the HVAC panel will come right off exposing the circuit board. I was happy to see a whole bunch of in-circuit test pads all over the back of this board. Close inspection with an eye loupe shows that they tested this PCB on a bed-of-nails test stand because almost every one of the test pads has a tiny pin prick in the middle of it. Anyway, I found the rubber conductive membrane switch contacts for the ESS feature and discovered that one side of that switch is ground and the other gets grounded to toggle the switch. Further, the non-grounded side of that switch has a via nearby that routes the switch trace to the back side of the board and onto a test pad. This is perfect. I don't want to solder onto a via because of the rubber membrane on the board, but the test pad will work nicely.

Wisconsin Mike said:
A small gauge mod-wire on the test pad and a bigger 24Ga wire on the ground plane wired over to an electromechanical 12V mini relay and this part is done. The solid state time delay relay will toggle this mechanical relay.

I attached the white electromechanical relay to the PCB using double sided tape in an area where the back cover won't interfere (it has some webbing molded in to support the PCB). I knotted the relay power wires to act as a strain relief and covered them in sleeving and ran them through an existing hole in the back cover.

Finally, I programmed the time delay relay following the instructions from their website so that it waits 1 second and then pulses its output on for maybe a quarter of a second, then shuts it back off. That pulse drives the mechanical relay to simulate pushing the button. Further, if I wanted, I could even add a switch to this setup to break the connection between the solid state relay and the mechanical relay so that it would default back to "normally enabled ESS" operation. For now I'm going to drive with it like this to see how I like it.

This is awesome. I just was looking for a TDR last night and I bought the same TRD you selected! Thanks for the post - This will save me a ton of time and fix it to work as it should have been! Me and my starter thank you

.

NZOLIVER · Mar 18, 2016

Hi all
I will do this and have a module in mind. Bit I will wait until it is out of warranty as if ANYTHING goes wrong with the control unit they will reject the claim!
There is an outfit in Europe someplace supplying a module just for this thing. They even have plun'n'play units for some VW and Porsche units I believe. More will be available i'll bet!!!
It is weird, as my wife's Fiat lets her keep the system switched off if she wants to (which she does

)

Oliver

nocaps · Apr 25, 2018

Since I didn't see anyone mention it, there is another factor used in the stop/start decision and that is the rate of deceleration before the stop. If you come to a stop very slowly ESS will not activate. I think this function is intended to eliminate the undesirable engine stop that occurs when pulling into a parking space and it does work if you come to a stop slowly (more slowly than most of us do however so many have not noticed this feature.) But try it yourself... come to a final stop very slowly and ESS will not activate.

.

VABadger · Apr 26, 2018

Mike I was with you until you started the 3rd post at 1215 AM, you lost me after that. By the way is your Cherokee you still under warranty?

matthewmorgan101 · Sep 26, 2019

Mike,

This is exactly what I am trying to do in my 2016 Jeep Cherokee. The only issue is your link is dead, and I cannot manually find a substitute device. Are you able, or someone else, to link that singl/ delayed pulse output dry relay? I cannot find one ANYWHERE. PLEASE HELP!!

Mark_ · Sep 26, 2019

matthewmorgan101 said:
Mike,

This is exactly what I am trying to do in my 2016 Jeep Cherokee. The only issue is your link is dead, and I cannot manually find a substitute device. Are you able, or someone else, to link that singl/ delayed pulse output dry relay? I cannot find one ANYWHERE. PLEASE HELP!!

Hi there and welcome to JCC :wink:
Mike posted the thread almost 4 years ago, and he hasn't been active on this forum since last October (2018).

It does seem like the relay has disappeared from Amazon. Searching with the part number, closest I can find is this :
http://timers.shop/Multi-Functional-5V-20V-Time-Delay-Relay-Timer-5-amp_p_12.html

HTH

Auto Start-Stop ESS Invert Modification

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