Random LR4 Death and Resurrection

avslash · Jun 13, 2022

Drove the Rover to the store over the weekend and locked the door via the touchpad on the handle. Came back out and unlocked with my key fob. Got in the truck and it was dead as doornail. No interior lights, no start when pushing button, no accessory mode or info screen light up, locks wouldn't activate again, just nothing. It behaved as you would expect from a truck with an absolutely dead battery.

I crawled through the back seats to access my tools (hatch wouldn't open either), and pulled out my voltmeter to take a battery reading. Thankfully the hood still uses a good old cable connection. Both batteries read at 12.9 volts, so that wasn't the issue and I began to get a little nervous at that point. Sat there pondering for a minute or two and then decided to pull both battery cables on the main battery and do a hard reset by touching the terminals together for 30 seconds. Voila, truck resurrected itself and behaved absolutely normally. Pulled out my GAP tool and no codes were set.

Mine is a 2012 that I owned since new, with about 100K on it. It has never exhibited anything like this behavior before. Anyone ever experienced something similar? Was this just a software crash on a processor somewhere? Just seemed bizarre that it came out of nowhere and then disappeared completely. Have driven it over 300 miles spanning two days since, and no apparent issues since.

CRYA · Jun 13, 2022

I've not experienced that in my 2012. Question is does a hard reset remove any codes that may have been in there? Also, did you get back out and try locking and unlocking it again, either with fob or touchpad? It almost seems like something went wonky there in your sequence.

avslash · Jun 13, 2022

I did get back out and try the keyfob again. Nothing. Just dead. Good point on codes, but nothing set after 300 miles of driving and mulitple stops/restarts. I even tried the "hold the keyfob under the steering column" procedure. Again, nothing. It would not even pop the hatch/tailgate via the electric actuators.

I was starting to suspect something global like a CJB failure or inertia switch failure.

As it's running fine now, I can only think one of the processors crashed during "boot up" when I unlocked the truck.

ryanjl · Jun 13, 2022

Maybe a too-simple thought, but was there maybe a bad connection with one of the battery cables that you unknowingly fixed when you put them back on the battery?

ftillier · Jun 13, 2022

I always read battery voltage on the battery clamp, and not the post, to rule out possibly bad/corroded connections, though generally without much load there's not a ton of difference unless it's really bad.

avslash · Jun 13, 2022

ryanjl said:
Maybe a too-simple thought, but was there maybe a bad connection with one of the battery cables that you unknowingly fixed when you put them back on the battery?

Had not considered that. Possible, I guess, but I did drive the truck about 6 miles to the store without issue.

avslash · Jun 14, 2022

ftillier said:
I always read battery voltage on the battery clamp, and not the post, to rule out possibly bad/corroded connections, though generally without much load there's not a ton of difference unless it's really bad.

Battery terminals are clean without any corrosion. Batteries themselves are only couple months old.

Although, a faulty connection would explain the symptom.

djkaosone · Jun 14, 2022

Try an ohm test from the negative battery post to various grounding points of the engine bay. It might be the main grounding post behind the wheel well.

tomwilley · May 5, 2023

avslash said:
Drove the Rover to the store over the weekend and locked the door via the touchpad on the handle. Came back out and unlocked with my key fob. Got in the truck and it was dead as doornail. No interior lights, no start when pushing button, no accessory mode or info screen light up, locks wouldn't activate again, just nothing. It behaved as you would expect from a truck with an absolutely dead battery.

I crawled through the back seats to access my tools (hatch wouldn't open either), and pulled out my voltmeter to take a battery reading. Thankfully the hood still uses a good old cable connection. Both batteries read at 12.9 volts, so that wasn't the issue and I began to get a little nervous at that point. Sat there pondering for a minute or two and then decided to pull both battery cables on the main battery and do a hard reset by touching the terminals together for 30 seconds. Voila, truck resurrected itself and behaved absolutely normally. Pulled out my GAP tool and no codes were set.

Mine is a 2012 that I owned since new, with about 100K on it. It has never exhibited anything like this behavior before. Anyone ever experienced something similar? Was this just a software crash on a processor somewhere? Just seemed bizarre that it came out of nowhere and then disappeared completely. Have driven it over 300 miles spanning two days since, and no apparent issues since.

Hi, I have 2012 LR4 Lux.
Exactly the same thing happened to me today. Car was running fine. Stopped it, got out and tried to lock. Neither the door button or fob did anything. Got in and tried start the car … absolutely nothing. Tried to turn on hazard lights, nothing.
Then after say 30s, the dashboard flickered and all the electrics came to life and seem as they should be.
Started, stopped, drove and everything works just as it should be.
I’m wondering rather than some kind of electrical fault, it’s a software fault. Often a processor will have a watchdog timer which the software resets continually. If the software hangs up for some reason, it doesn’t get to reset the watchdog timer. The watch timer then runs out and triggers a hardware reset. Feels the same process.
I am just guessing here … maybe wishful thinking though. Very interested to know if your problem came back.

iSurfvilano · May 6, 2023

@avslash Has it rained lately? I've seen this before in a few other Land Rovers (including my full size RR) when there's a leak and water is causing a temporary short due to it sloshing around underneath before it's noticable. Check under your carpet, could be the infancy of a busted sunroof drain.

Random LR4 Death and Resurrection

avslash

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CRYA

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avslash

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ryanjl

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ftillier

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avslash

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avslash

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djkaosone

'11 LR4 HSE LUX 5.0L V8

tomwilley

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