2010 LR4 V8 Electrical Problems (Big Surprise)

I am a long time Land Rover owner and have always worked on my own cars, but I am not necessarily the electrical engineer that I need to become to work on this car. But I am undaunted and ready to learn.

I have a new to me 2010 LR4 V8 and I have been having problems with multiple misfire codes on driver’s side bank and a slow coolant leak that I haven’t been able to track down yet. I have been chasing down these codes with a generic BlueDriver bluetooth code reader, but I think I have a larger electrical issue that might be causing contributing to these problems.

It has happened two times to me and when I related the experience to my wife she says it has happened to her as well.

THE PROBLEM:
I was waiting in the truck, not running, for my daughter to come out of basketball. When I went to start the truck, nothing. No dash lights, no navigation screen, no cute little picture of the LR4 on the dash, just complete quiet and darkness. I noticed the brake pedal was really firm gave a hard push on the pedal, pressed the start button again, it made a clunk hesitated and fired up, but with “restricted performance”. Shut truck off. Waited a second. Started as normal with no restricted performance but was stumbling at low rpm. But to my surprise the CEL light is now off, all the codes are gone except for the permanent ones and the clock and date are reset to 2009, as if I had disconnected the battery and discharged the electricity by touching the positive and negative cables together.

Any thoughts?

Bad battery?
Loose ground?
Lucas Prince of Darkness?
The malingering ghosts of Fix On Race Day?

I am retreating for now to the relative calm and clatter of the 300TDI in my Range Rover, awaiting orders from the internet.

P.S I know this is chevy v. Ford territory but suggestions on a better code reader? Also, is there one that will work on both this Land Rover and a BMW X5?

Thanks in advance.

GAP IID is a good code reader for this car. Full functionality - see/record all live values, reset adaptations, adjust suspension, program keys, etc. It would probably help you track down the misfire situation as well. You can use for two trucks. The IID is VIN locked, but I think you can buy additional licenses for something like $80.

I saw from your post in the other forum that you checked the alternator/battery, etc., and you’re moving on to checking grounds. Regarding the fusible link/fuses - yes, there are plenty of these. But once it goes, it wouldn’t come back. The fact that your power came back seems to rule out a fusible link/fuse.

I’m guessing you must have lost power to the entire instrument cluster including the clock and the ignition switch. Maybe start looking an the electrical diagram and see if there is a common ground someplace. The electrical diagrams are floating around if you don’t have one. I posted some links a while back to some repositories in overseas forums. If you can’t find it, let me know and I’ll track it down.

The fact the pressing the brake pedal hard allowed you to start the car might point to the brake pedal position switch, but that would not explain the clock reset - so probably not it. More likely, the pedal built-up pressure after pressing it with no ignition signal the first time. Then you had to press it hard to get it down far enough to trigger the switch on the second attempt. Not sure. Still - might just check to make sure your brake lights are going on and off with the pedal. If not, brake switch should be replaced.

Thanks for your reply. The gap tool seems like the way to go. I will search for those electrical diagrams.

Are their online manuals for LR4’s like there are for older models?

I will check the grounds for the instrument cluster but the seat of my pants feeling is there is no power anywhere in the car, but I will check this next time it happens.

Is there a chance that the fact that the key fob sat in the car with me for a while and the doors remained shut that the alarm system is cutting power and not allowing the car to start?

The LR4 service manuals are available through the Land Rover Topix website, but you need to pay for access (by the hour, day, week, etc.). Pricing varies based on what you’re looking for and whether you narrow it down to a particular model.

There are online manuals posted in various forums, mostly overseas. I think at least one of the following should have service manuals and electrical diagrams:

http://www.disco3.co.uk/forum/discovery-4-wiring-diagrams-146859.html

http://landyonline.co.za/landyforum/viewtopic.php?t=5643

Grab the electrical connector reference as well: https://disco3.co.uk/gallery/albums..._LR4_CONNECTOR_QUICK_REFERENCE_GUIDE_(1a).pdf Use it in conjunction with the wiring diagram to locate the various connectors referenced in the wiring diagram.

I don’t think having the key fob in the car would cause this problem. I think it can slowly drain the battery just having the fob in the car, but I don’t know why it would cut power. It did occur to me that maybe the antenna module (which detects the key) could be acting up. But, again, it shouldn’t cut power to the clock.

It could be a problem (ground, short, bad connector) at the central junction box (CJB)/body control module (BCM). The CJB/BCM is located behind the glove box. You’ll see from some of the views in the connector reference guide that there are two or three main ground points on that side. Might be a good place to start. Take note of any moisture or evidence of past moisture. I know some owners had trouble with passenger side flooding for various reasons. Anything like that can obviously create some corrosion.

If you’re having trouble finding anything, let me know. The diagrams are a bit overwhelming at first, but after you stare at them a while, they start to make sense. I’m no electrical engineer either - nor a mechanic - just learning as I go.

Thanks for all the links to the manuals. I’m sure my eyes will be crossed for the next few days.

I will be sure to check the grounds behind the glove box.

The part of my problem that surprised me was less that the car wouldn’t start (I’m used to that with Land Rovers) but that all systems were reset, clock/calendar, window controls (I had to have them relearn the top stop to automatically close, but most importantly the part of the computer that stores fault codes and illuminates the CEL. It really was as if the battery was disconnected from the whole truck and the positive and negative leads were touched to reset the vehicle.

Glad the weather is better for a sit and think in the LR4 with a multimeter today.

Most likely a bad ground or loose connection is the first place to start. Then check the battery, then alternator.

if you get misfire, it could be unrelated but not 100%. These trucks do some really wonky things when they get voltages they don’t like.

your coolant leak is likely one of three things...a leaking water pump, a front crossover pipe, or the rear crossover pipe. I would go ahead and replace all three at the same time. They are all something you can do at home if you are capable of turning a wrench.

Gap IID is well worth the $. I’ve saved myself thousands and a lot of headache with this thing.

@cbkearney. I agree - it’s like all systems reset. However, you don’t know what was causing the CEL, so it’s hard to say from that part where the problem occurred. I would expect most things that cause a CEL go through the engine junction box, but some functions might go through the central junction box. Once the condition that was causing the CEL is resolved, the CEL will disappear.

I am reminded just now of a post or blog I read one time about a ground point in one of the front wheel wells - I think it was passenger side. The post mentioned that this particular ground point was notorious for getting corroded and causing people to needlessly replace batteries and alternators. I believe you need to remove the fender liner to see it.

On that electrical connector reference guide, the ground points are labeled with a dot before the connector reference. I see one group of ground connectors in what appears to be the passenger side front wheel well. At least one of these connectors goes to the engine junction box. So, might be something to check.

The tough part here is that you’re looking for an intermittent fault to ground, so you testing from the junction box probably isn’t going to help much. You actually need to check the ground points for loose connections/corrosion. If it were me, I’d maybe check the main engine and central junction box grounds, then wait until the gap tool arrives. Any codes that show up might save you a bunch of time chasing things.

Finally, search for TSBs if you haven’t already. I just did a very quick google search for the CJB and came up with this document mentioning a failure to start and some problems with the CJB on the 2010 LR4. https://static.nhtsa.gov/odi/tsbs/2014/SB-10071055-6903.pdf. No idea if its related here, but as you start looking at things, it might be good to be aware of known issues.

Thanks so much for you help. I have some action items to check rather than hunting and pecking for a fault that isn’t always there.

I will use that document to check and clean all the grounds and see if I can find the leaking coolant.

Take this or leave this but it's almost always a bad battery in my experience. This is typical behavior of many modern cars when the battery is down a few cells.
Modern electrical systems do some weird stuff when the battery isn't at peak performance. The battery may not even test bad but replacing it will fix it. Had this happen twice (not with the LR4, an X6)
Step one for me in this situation is a new battery.

I agree with Al that it is likely the battery. I have not bought the Gap Tool yet. I own a Foxwell NT510 Elite that I bought for my wife's X5 and I saw that I can buy Land Rover for like $60 and download it to my 510. It has two-way communication and can do active testing and brake bleeding. I'm still researching to see the differences. I know the Gap Tool can, for example, adjust the height of the Rover which is great. I don't think the Foxwell can do that. The question is if it is worth the extra $400+ or not for diagnostics.