Adaptive Cruise Control and Emergency Breaking error
Recovery Vehicle
Joined: Mar 2020
Posts: 1,078
Likes: 713
I am headed into Seattle tomorrow for same issue. Car is great in all other respects but randomly I will get 3 or 4 in a day. Always on start and they always go away the next start after a short sit. Usually I have AHBA flipping off and a stall for presentation of map on driver info screen about the same time. Then the car is flawless for a week or more then it’s a repeat. I am trying to catch the warning with my FIXD OBD2 reader to see if there is a code.
My completely uneducated guess is there is some sort of stray signal on start occasionally that makes these items occur. I thought maybe I had a bad battery as others have reported. JLR says it checks good but for me it never reads above about 12.2-12.3 volts after a day of driving. That’s 60-70% for an AGM which seems odd. If I charge it up to 13V which is 100% and it just sits it will drop back to 12.3 volts. I just wonder if there is some management module that isn’t right. That said there shouldn’t be any relation to start up issues at 12.3 volts which should be plenty. I just cannot think of any other cause except of course software. In the absence of anything I can read or hear from JLR I am starting to make up my own answers I guess. Message to JLR.
I will post if I find resolution. Everyone is great about helping at dealer but somewhere someone must know or is working this issue- wish I could just know it is being worked
more later
My completely uneducated guess is there is some sort of stray signal on start occasionally that makes these items occur. I thought maybe I had a bad battery as others have reported. JLR says it checks good but for me it never reads above about 12.2-12.3 volts after a day of driving. That’s 60-70% for an AGM which seems odd. If I charge it up to 13V which is 100% and it just sits it will drop back to 12.3 volts. I just wonder if there is some management module that isn’t right. That said there shouldn’t be any relation to start up issues at 12.3 volts which should be plenty. I just cannot think of any other cause except of course software. In the absence of anything I can read or hear from JLR I am starting to make up my own answers I guess. Message to JLR.
I will post if I find resolution. Everyone is great about helping at dealer but somewhere someone must know or is working this issue- wish I could just know it is being worked
more later
13 volts is the absolute upper limit and if held there long will destroy the battery. This is why you CANNOT use a lead acid charger on an AGM -- it will drive the battery to too high a voltage and hold it there. Been there -- destroyed two brand new AGM batteries on my boat.
This AGM thing is all about the electronification of automobiles --- making them into rolling computers. Apparently, computers are very sensitive to voltage variation, or so it must be.
I just recently did not drive my Defender for a week and sure enough, start getting the "battery low, please start the engine" warning. So, now, I run the battery for 25 minutes while I am nearby working and it is happy.
In the lead acid era, such a warning would have the starter motor just turn over to start the car. Now, there is plenty of voltage for the starter motor --- it is just the computers which are sensitive to anything below 12 volts or above 12.5. So it goes.
Enjoy !!
Last edited by TrioLRowner; Apr 13, 2021 at 04:46 PM.
Mudding
Joined: Oct 2020
Posts: 148
Likes: 45
From: Anacortes Wa
I just completed a short trip to my dealer. They said JLR knows about the Emergency Braking and Steering issue and does not have a fix at this time. They also software updated 2 modules which fixed long standing annoying nits for me- first the sometimes lag in appearance of the map on the drivers panel. This is not the PIVI Pro map. I had found I really liked full map display or map on the info panel between a 2 dial setup. Full map though is a wonderful feature and now it really snaps to life on start.
The second fix was the AHBA toggling off randomly. Only annoying because I know what the light symbols mean on start so I instantly notice it. That was corrected as well
When they get the Emergency Braking and Steering warning sorted I think my 2020 P300 will be sorted out completely. Still runs like a dream and I really enjoy driving it.
I finally really put my foot in it the other day at around 6500 miles and that 4 cylinder really goes when needed. It is relative I realize never having owned a true sports car
The second fix was the AHBA toggling off randomly. Only annoying because I know what the light symbols mean on start so I instantly notice it. That was corrected as well
When they get the Emergency Braking and Steering warning sorted I think my 2020 P300 will be sorted out completely. Still runs like a dream and I really enjoy driving it.
I finally really put my foot in it the other day at around 6500 miles and that 4 cylinder really goes when needed. It is relative I realize never having owned a true sports car
4wd Low
Joined: Mar 2021
Posts: 11
Likes: 5
I had that message pop up on my Jaguar XF once, going through a drive through - slow rolling forward. Haven't yet seen it on the Defender but it would appear the message/glitch is similar. So many computers and driving "aids"...
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