2012 LR4 92K

After 20 minute drive... everything starts failing except for driving ability.

AC Turns off
​​​Tire pressure warning than goes onto system fault
Music turns off
Infotainment turns off and then reboots
The instrument cluster displayes warnings...
dynamic stability not available,
hdc not available
then the instrument cluster display turns off and reboots
SIGNAL LIGHTS DO NOT WORK
EVERYTHING tries to restart and then turns off... stuck in a loop..
The car drives fine!

I pull over... turn off the car... try to close it and walk away. After a minute or two.. I come back... start the car and everything is fine for another 20 minutes or longer.

This is the weirdest thing I have ever seen!

Anyone experienced this.... can anyone shed some light on the issue?

 

make sure that the ground wire to the right fender is tight. I had a nightmare with our 2006 RRS and a faulty ground. Phil

 

I’ve seen posts about that right front (passenger) side ground multiple times. Definitely something to check. The rebooting sounds kind of like a loose ground.

But, even more basic, have you checked your alternator and battery, and have looked for any diagnostic codes? The battery management system on these cars will start to shut various non-essential circuits down as it detects low voltage. That seems consistent with at least some of what you’re seeing as symptoms.

The other common thing I seem to see in the forums that leads to multi-system failures is corrosion in the junction box and wiring harnesses as the result of water getting into the passenger side of the cabin behind the dash and in the floor. Usually from a leaking sunroof drain.

 

Thanks for your input


I did have a leaky sunroof and my passenger carpets were wet.
I unclogged the drains, lifted the carpets, exposed the wiring harnesses and dried everything up.

I was trying to look for anything out of the ordinary but couldn't find anything. Wires look to be in good condition... didn't see any connectors there.

Is there anything in particular should I be looking for?

Also I looked at the fuse box very carefully.... got it loose to take a better look but since I didn't see any water marks... any indication of it being wet I left it alone... I did not take it out or unplugged it..

The battery looks to be fine. Over 12v over night..
Will take it to a shop for charging system check.

there was a bit of crud on the terminls... I removed the leads and cleaned the terminals. The ground looks/ feels solid.

I read on here that the instrument cluster plug might be loose... should I attempt to remove the cluster.. plug and replug? Also... I dont think its related but for some time now... the rpm needle flickers sometimes.... I think the led is going bad.... been happening for a few months now so I don't think these issues are related.

thanks again for helping out

 

With regard to the battery - over 12v is not necessarily enough. 12.2v, for instance, is considered basically dead. Really should be at 12.6v. Running, you should see about 14.5v - if not, alternator might be shot.

As for corrosion in the passenger well, I can’t say what to look for specifically. Inside ny plug or ground point is fair game for wreaking havoc.

Instrument cluster plug is an interesting thought and definitely worth checking.

The other thing you could do is use the wiring diagram to trace back all those functions that are quitting - see if they all belong to a single module or even a single plug. I think a lot of these go through the BCM, which is in that passenger side of of the cabin if I remember correctly.

A little strange that it seems to go out at 20 minutes. Almost like something is overheating. Wonder if there’s a bad relay someplace.

 

I'm getting 12.3V in the morning and 12.4 idling.

The BCM is a good idea... I will try to find it and check the connectors.

Didn't think of solenoids! Great tip! I have a friend with a test tool for these... will pull them out and test all.


Thanks for your input!

 

12.3v is pretty low for the morning and 12.4v is way too low for idle - that would be a bad alternator. Did you mean 14.4v. at idle? That’s what you should be seeing.

 

Yup a typo... im getting 14.4 idling.

12.3 too low in the morning??

 

12.3v in the morning is pretty low. You’re probably only at 60% charged at that point. How old is the battery? Was anything “on” in the car when you tested? The best way to test is to disconnect the ground, but I don’t like having to reset stuff, so I pop the hood, close the doors, and let the car set for about 15 minutes for all the systems to go back to sleep (someone did a detailed study on parasitic voltage and it really does take about 15 min before all the systems shut back down). Then I go back and check the voltage (without the key in my pocket - even approaching the car with the key is liable to turn on certain systems).

You also can check cranking volts. When cranking, it really shouldn’t drop below 10v. If you have a min-max setting on the multimeter, you can check yourself, or just watch the multimeter while someone else cranks. Or, just take it to an auto parts store and have them run a test on the battery.

Another idea: if you have a scanner that you can leave plugged in while running that will show your running volts, you could see what happens to the voltage reading when your systems go haywire - see if there is a sudden drop or spike or anything. It would also be good to watch your running voltage with the RPMs up to see if your alternator is spiking or dipping, which could indicate a bad alternator or slipping belt.

 

I had the exact same problem. Took it to the dealer and they replaced the bcm. It’s been running great ever since