Flat battery - problem solved?

[Richard Tanner]

I wrote some weeks ago about the battery on my Range Rover 4.6 going flat every couple of weeks and received some helpful ideas - thanks. Land Rover have had it for 3 weeks now, trying to isolate the leak. They tell me that they have disconnected each circuit but still cannot find it. Now they have replaced the body control unit and find that the leakage appears to have stopped. Their next test is to replace the old BCU to see if the leakage comes back - if so they will conclude that the problem was the BCU and no doubt bill me accordingly!! Any thoughts on this would be appreciated. Thanks.

[scoobymick]

Hi Richard,i have changed many BeCM's for current draw. What usually happens is it sees a system as active,e.g it thinks a window is still open and powers it to close. Every time it does this,it's prevented from going into 'sleep mode' and subsequently flattens the battery. I have also known it to be associated with a door latch fault,often the o/s/f. The latch motor burns out and causes a fault within the BeCM,but as you haven't mentioned a door fault that particular one is unlikely.
Mick

[Richard Tanner]

Many thanks for this - that is a really interesting response and one which I will raise with Land Rover today. Richard

[rovertech]

i hope you r prepared because becm's cost in the 1200 dollar range plus labor just wanted you to b aware

[Richard Tanner]

Thanks all for the words of wisdom. After several weeks of diagnosis, LR have returned the car saying that they have reset the BeCM. They say that they cannot detect any leak after a week or more of testing. I have only had the car back 3 days and it starts fine but the VDU shows "alarm fault" each time the key is inserted. I fear that all is not well. Do you think that perhaps the alarm has contributed to the problem? Living in Hong Kong, we are surrounded by cars and blocks of apartments with automatic gates. That might explain why LR wanted to check the car on site. Any further ideas would be much appreciated. Best wishes, Richard

[scoobymick]

Richard,I'm not sure what spec the alarm system is on your car,but does it function perfectly? If it has superlock,is that ok? Does it signal a mislock when you arm it? I am still suspicious of a latch,and I don't know of anywhere on T4 that allows you to reset a BeCM.
Mick