2008 LR3 HSE, vehicle running solid, and has a less than 2yr old dealership replaced cluster.

Went on a camping trip, drove there without issues, parked, used headlights to illuminate fire building for 15 minutes, then car wouldn't start. It simply wouldn't click over, sounded like/assumed a dead battery (adn therefore possibly a bad alternator rearing its head), but the lights still worked AND the instrument cluster said "TRANSMISSION FAULT." Uh oh...

Connected Gap iiD, saw several new faults, cleared all, car started right up and drove home no problem. The only sign something was off was that all the trip metrics had reset to zero (trip odometer, MPG, avg. speed, etc.)

The faults were:
1) TRANSMISSION> P0826-00(2c) up and down switch input circuit
2)ENGINE PETROL> U0167-00 (68) lost communications with vehicle immobiliser control module
3) INSTRUMENT PACK> B1A87-68 (2F) Battery disconnections/electronic control unit reset - algorithm based failure

I've seen fault #1 once before, and it appears to not really be a big deal in and of itself. But the other two faults I have never seen before and the instrument pack saying there was a battery disconnection/ECU reset seems not good to have show up randomly and if I hadn't have had my Gap iiD it seems like potentially something with the immobiliser control module might have actually stranded me and prevented me from starting the car (as it had already done that in the first place).

My question isn't necessarily "what do each of these mean" (although I'm not against that insight!) but rather, is there anything to glean off the combination of these faults showing up after my car randomly wouldn't start?

 

If it was the mobilizer it would still crank. If headlights were on then the truck was running ,right? They can not be on with engine off. At least not in any LR3 I have been in. But if somehow they were on, engine off, that is certainly enough to kill the battery. None of the faults seem super critical and could have been caused by a "brown out" situation where power was just too low and one gets these odd codes. Maybe after sitting a bit while using the GAP was enough to let the battery stabilize for starting.

Obviously also make sure battery terminals are tight.

 

My lights were in fact on with the engine off, but for less than 10 minutes, so I didn't think it would even get close to draining the battery...
... but you make a good observation here because, perhaps the faults were triggered in reverse of what I was thinking: that actually, the head lights on without running the engine somehow drained the battery to zero/very low and it wouldn't crank, and that perhaps THAT triggered faults #2&3, and that in there somehow clearing faults and being able to start again maybe just gave the battery a minute to "recoup" by not having lights on and waiting 5 minutes to start it again.

 

It kinda the scenario I am thinking. I don't know of any faults that will prevent engine cranking. Usually cranking issues are battery, ground, main fuse (big 400 amp by pos battery post) or faulty starter. If you do water crossings, the starter can suffer - I know this so very well. I added breather tubes to my last install.....

I would say keep an eye on things and see if any codes return, etc. if not, one off event.

 

Totally. Thanks for the good insight here, I appreciate you taking the time. And now I can at least test against this theory with fingers crossed it's a one off where I made the battery unhappy in a new and exciting (and now avoidable) way. As always, we'll see what happens and observe what we can but this is really what I love about these forums and this community.

 

If you do a decent amount of camping and going to remote places I highly recommend an aux battery setup. Less than $400 can give peace of mind on trips. Being able to jump start yourself as well as simply draining the aux battery for stuff versus the starting battery.

 

Even before this weekend, this was actually the next mod I think I'm going to. I already carry a NoCo jump pack unit but, I want to do an actual dual battery setup.

I will say, I'm torn between the feasibility of doing it myself or paying someone for their expertise, but it feels like it gets expensive fast. I've done a bit of research on it but haven't seemed to land on a clear winner... seems everyone has a different approach, some folks are making their own battery cables and repurposing boat solenoids, others are using premade packs ordered online, and all seem to know a lot about electricity and there seems to be a lot of inside baseball talk that makes it feels intimidating - although sometimes reading too much isn't helpful either.

How'd you do your setup? Two identical batteries? Mounted under hood somewhere? premade or full DIY?

 

Yeah, lots of options. I did this setup and its been flawless for years:

https://landroverforums.com/forum/lr...install-93813/

 

Lights do work without engine running and if i switch engine off before turning lights off ( rare occasion) i get the "follow me home " dash message and lights stay on for about 10 seconds.
A good dual battery system i'd say is almost a necessity on these power hungry vehicles if you spend any time camping, it was the 2nd accessory i added to mine after i bought it.

 

Any idea how old your battery is? My 5 year old battery failed on me last year and I had to use my jump pack twice to get home at the end of a 10 day trip. After driving for a while the car would start on the battery but be dead in the morning. You could get it load tested at a battery shop. On another car I had a battery replaced under warranty after only 12 months as it tested weak.

I don't see how there is enough room to install a second full size starting battery but one for accesories like a fridge is possible. Simplest way would be to use a DC to DC charger between the cars 12v system and the second battery. Two wires from the charger output go to the battery. On the input side two wires go to the cars system, preferably the battery. A third wire on the input side goes to a source of switched DC that is only on when the car is running. This turns on the charger when the car is running. When the car is off the two batteries are isolated. I was previously using a voltage sensing relay to isolate my fridge battery but I was concerned one of the two batteries, a big staring battery and a small 100 Ah AGM battery, might not be getting fully charged because of the different capacities so I added the DC to DC charger. This works as a 3 stage charger for the fridge battery and should keep it fully charged and not overcharged.