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Auto Start Stop Warning Light Jeep Compass

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Service Stop/Start System Warning Light - P2AF6

  • Thread starter KarnaughMI
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KarnaughMI
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It's amazing that Jeep has not been able to solve this problem since the release of the 2018 JL. We have a 2018 Grand Cherokee with the 3.6L and ESS and it has worked flawlessly since we owned it from day 1. My background: former ASE mechanic and Electrical Engineer. So I am familiar with the technology and know enough to be dangerous.

But, here's our story...
So, we picked up our new '19 JLUR on 16 January from Safford in Warrenton, VA. Things went GREAT, sales person was great. Drove it home and the ESS Service light tripped on, cycled the car, cleared. I figured it was a fluke and was due to something from sitting. Day 2, light tripped on again so I called my salesperson and she talked to the service manager and we were told to bring it in on Monday, 21 January. Light tripped again on Sunday before we went in. When we took it in on Monday, the light was not on and according to service, there was no persistent code. They test drove it a few times and couldn't recreate the problem (in my head I am like, YA, NO DUH!). Not sure if they did the GR8 battery test or whatever else they did.

Regardless, nothing solved. Fast forward about a week and the light came on again while my wife had the Jeep. She took it straight to the dealership and asked them to get the tech and scanner and not to shut it off (since the code clears ALL the time on engine cycle). The service tech came out, and even though my wife EXPLICITLY said not to turn it off, he shut it off and proceeded to get a snarky smile with my wife and argue with her about this is how it is supposed to work. After some back and forth (oh I wish I was there), he finally said we would need to bring it back on the 28th and he would have to email FCA for assistance.

Took it in on the 28th and they had my vehicle for about a week and a half (the cover/shield for the ACC was scratched during one of my service calls ... (smh)) and they replaced the PCR. Picked it up on the 5 February because they said FCA wouldn't cover the rental any further (!!) while we are waiting for the ACC cover.

Lastly, since the 28th, I have had the light trip on three more times, took videos of it twice to add to the early pictures, and fortunately, one of those I was able to get to A dealership to get them to pull the code. Even there, they tried to tell me that this is how the system is supposed to operate (!!). Best part, I called Safford and have not heard anything back from the service writer or the service manager after calling them both on the 7th.

Here's our code: P2AF6 - Starter Relay 3 Stuck Off

This thing is bordering on lemon law territory with me and I really do not want to go there. But less than 1,000 miles and we haven't even made our first payment yet. We have been Wrangler and Cherokee owners since the 90s and love our them both ... warts and all. But this makes me reconsider my purchase.

Now if I could only get a hold of the service manager on Monday to get it in for the THIRD time! :punch: :headbang: :angry:
At least this time I have a code for them to work with! :angry:

Sorry for being long-winded, I needed somewhere to vent.

-Tom

GreyFox
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  • #2
It's amazing that Jeep has not been able to solve this problem since the release of the 2018 JL. We have a 2018 Grand Cherokee with the 3.6L and ESS and it has worked flawlessly since we owned it from day 1. My background: former ASE mechanic and Electrical Engineer. So I am familiar with the technology and know enough to be dangerous.

But, here's our story...
So, we picked up our new '19 JLUR on 16 January from Safford in Warrenton, VA. Things went GREAT, sales person was great. Drove it home and the ESS Service light tripped on, cycled the car, cleared. I figured it was a fluke and was due to something from sitting. Day 2, light tripped on again so I called my salesperson and she talked to the service manager and we were told to bring it in on Monday, 21 January. Light tripped again on Sunday before we went in. When we took it in on Monday, the light was not on and according to service, there was no persistent code. They test drove it a few times and couldn't recreate the problem (in my head I am like, YA, NO DUH!). Not sure if they did the GR8 battery test or whatever else they did.

Regardless, nothing solved. Fast forward about a week and the light came on again while my wife had the Jeep. She took it straight to the dealership and asked them to get the tech and scanner and not to shut it off (since the code clears ALL the time on engine cycle). The service tech came out, and even though my wife EXPLICITLY said not to turn it off, he shut it off and proceeded to get a snarky smile with my wife and argue with her about this is how it is supposed to work. After some back and forth (oh I wish I was there), he finally said we would need to bring it back on the 28th and he would have to email FCA for assistance.

Took it in on the 28th and they had my vehicle for about a week and a half (the cover/shield for the ACC was scratched during one of my service calls ... (smh)) and they replaced the PCR. Picked it up on the 5 February because they said FCA wouldn't cover the rental any further (!!) while we are waiting for the ACC cover.

Lastly, since the 28th, I have had the light trip on three more times, took videos of it twice to add to the early pictures, and fortunately, one of those I was able to get to A dealership to get them to pull the code. Even there, they tried to tell me that this is how the system is supposed to operate (!!). Best part, I called Safford and have not heard anything back from the service writer or the service manager after calling them both on the 7th.

Here's our code: P2AF6 - Starter Relay 3 Stuck Off

This thing is bordering on lemon law territory with me and I really do not want to go there. But less than 1,000 miles and we haven't even made our first payment yet. We have been Wrangler and Cherokee owners since the 90s and love our them both ... warts and all. But this makes me reconsider my purchase.

Now if I could only get a hold of the service manager on Monday to get it in for the THIRD time! :punch: :headbang: :angry:
At least this time I have a code for them to work with! :angry:

Sorry for being long-winded, I needed somewhere to vent.

-Tom

So, what do you think it is? Mine goes in today for the service stop/start. I've already checked to make sure the fuses are clicked in. And yes, everything resets when the vehicle is turned off. I personally have not noticed any codes when I cycle thru the dash pages.
KarnaughMI
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I honestly wish I knew. They swapped the PCR when I had it in last and it still tripped the code.

I have not looked at the battery voltage of the GC while driving, but from reading some postings on the forums, it looks like FCA really adjusted the charging algorithm in the Wranglers to help with fuel economy by keeping the alternator drag the lowest while under engine load. It seems that the highest "charging" comes when braking or foot off accelerator. Normal driving is a lower than traditional voltage. Great concept, but I think it just made the system a little too touchy.

I would love to know what they did differently between my '18 Grand Cherokee and the Wrangler. With that, I think it would be easier to guess what it could be. I really don't think it's a wiring problem as my experience with wiring issues is they tend to show patterns and trends to help diagnose (and a little more frequency). It never trips when just driving. It only trips when it is stopping or starting (ya, kinda obvious ... lol) ... I have not seen it trip the service light while simply driving. That's where I think it's an overly sensitive PCR and/or the secondary battery and/or the charging algorithm...or some combination.

My one suggestion is not to let them "drive it around" to try to recreate it and when they don't to just hand it back. Unless it is tripping the light all the time, the odds are they won't find it. I should have argued more on the initial service call for them to contact FCA "technicians" to pull historical engine data to get the code.

Let me know how it goes.

-Tom

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They kept mine so they could drive it around and of course they can't replicate. I even told them it's rare that it happens. I have a feeling I will get it tomorrow without them doing anything. I'll get the code when I pick it up. Thanks for any advise. It sounds like this could be a crazy issue.
KarnaughMI
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That's great! Did they say which wire specifically was loose?

Mine is set to go back in tomorrow for another shot at this. I don't want to micro-manage (I hated when people did that to me when I wrenched years ago), but I don't see any detail from them in the receipts about what they tested/did. We will see.

-Tom

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That's great! Did they say which wire specifically was loose?

Mine is set to go back in tomorrow for another shot at this. I don't want to micro-manage (I hated when people did that to me when I wrenched years ago), but I don't see any detail from them in the receipts about what they tested/did. We will see.

-Tom

No they only said there was a loose wire from the ESS that would only trip at long stops. I looked at my paper and there are no codes on it. Sorry.
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My dealer told me the service stop-start warning light was normal on cold mornings while the battery was still charging. :facepalm:
Bummer. But I'm pretty sure that isn't accurate. When it's cold out and/or charging it specifically says so on your dash screen (#6? I think). So I would find a smarter dealer. I'm lucky in that mine seems to be willing to listen to me and it's a relatively small town.

Edit: it will say start/stop not available because temp too low or charging.

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Bummer. But I'm pretty sure that isn't accurate. When it's cold out and/or charging it specifically says so on your dash screen (#6? I think). So I would find a smarter dealer. I'm lucky in that mine seems to be willing to listen to me and it's a relatively small town.

Edit: it will say start/stop not available because temp too low or charging.

Yes, there's a big difference between it needing servicing and it being unavailable. To make things worse, this dealer overfilled my oil during a fluid swap this morning so it's currently being drained.

Unfortunately, the next closest dealer is an hours drive away.

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Yes, there's a big difference between it needing servicing and it being unavailable. To make things worse, this dealer overfilled my oil during a fluid swap this morning so it's currently being drained.

Unfortunately, the next closest dealer is an hours drive away.

Yeah, I drive about 40mins to mine. There's 3 nearby, but they suck lol
KarnaughMI
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So dropped it off again this morning ... light tripped on before I got there.

Got a call in the afternoon that the technician pulled the wheel liner and looked "up" into it and noticed a wire was not plugged in. Sounds like it was not properly crimped. They charged FCA for a connector to be replaced...but it definitely sounds like whether a loose wire or a wire hanging free or fuses not seated properly... there are some QC issues going on.

*fingers crossed*

-Tom

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  • #14
I also had the service start/stop system light coming on and mine was traced back to a malfunction in the door latch. I was able to track it down by unplugging the wire harness for the door and that turned the light off.
Darter02
  • #15
I also had the service start/stop system light coming on and mine was traced back to a malfunction in the door latch. I was able to track it down by unplugging the wire harness for the door and that turned the light off.
Ah ha! My ESS warning light began to come on this week. I've been driving my 19 JLU since December without a single instance of it turning on. Your comment makes me believe it has something to do with my doors. I removed the front doors the other day for the first time. I'll have to check my connectors out. Thanks for the clue!

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Auto Start Stop Warning Light Jeep Compass

Source: https://www.jlwranglerforums.com/forum/threads/service-stop-start-system-warning-light-p2af6.23428/