I have been trying to get my 2007 LR3 back on the road after a number of faults popped up a few days ago. The faults that are consistent every time are the HDC and transmission limited gears available faults and P0118 (engine coolant temperature circuit high input) and the air suspension drops as well. It sometime starts just fine but then that faults appear within minutes before I even leave the driveway. Other times it is very hard to start and the faults appear immediately. It will turn over just fine and start to catch but then quickly dies. It idles high in park, but not in drive. I don't know for sure if it's related but I discovered a cowl leak the had saturated the passenger side foot well. This has been dried out with a dehumidifier and I checked for corrosion on the wires under the door sill but didn't see anything obvious. There were only a few heat shrink wire splices along the passenger side wire loom and all looked fine from what I found.

I replaced the brake light switch and nothing improved. I inspected and cleaned the contacts on the transfer case module as this is another common suggestion with these faults and nothing changed.

Is it possible that the coolant temperature code could be the cause of this? I did replace the sensor on the thermostat housing a couple of years ago but I supposed it could have failed again. I do know that coolant temperature sensors can lead to hard starting but would it also trip the transmission and HDC faults and put the vehicle in limp mode?

Again suggestions would be much appreciated as I am out of ideas.

Thanks

 

Check battery voltage and running voltage.

 

Battery voltage is 12.9 and alternator is putting out 13.95. The battery was replaced about 2 months ago and the alternator was replaced two years ago.

 

Okay, those are pretty good. But I would not rule out some sorta ground issue. I would check the main battery ground at fender/frame (sorta behind fuse box in engine bay). Also the ground that is at the frame in the passenger wheel well, just forward the strut I think.

I would also get ALL the codes. Fund fact, I think it was P0118 that came up for me today. But it was because I had cleared codes with engine running, something these do not like. The result it the fan clutch fully locked.

 

Both grounds you mentioned are tight, clean and free of corrosion. Just to be sure I just cleared the engine codes with the engine off and P0118 won't even clear at all, even without starting the engine. Maybe it is the coolant temperature sensor causing the faults? Have you or as anyone ever seen that?

 

I would hazard a guess that as a fail safe you are getting the faults due to the coolant temp sensor faulting, replace it and then clear the code.

 

If your coolant sensor only has 2 wires you might be able to trick your the system by either unplugging it or jumping the two pins in the connector. This might get the system to think it’s really cold outside and allow you to clear faults and at least do a quick test drive.