Just sat in the truck, very still, for about three minutes -which is harder than you think! - and the dim red light didn't go out so guess the BeCM isn't going to sleep? What things does this control that I can check?

Cheers John, should be dark in about an hour so will take a look, where exactly is this LED?

How would you test the sleep mode, is it something a rank amateur like me could do?

There is no factory CD unit He couldn't check anything as it wouldn't communicate. Testing the fuses/relays identified the BeCM but couldn't diagnose what it's problem was....

The read out was as follows; Volts. 12.50 Measured. 453A Rating. 550A Starter test. Normal. 9.95v Charging test. Ok. 14.47v Battery was fully charged and put back in this morning, three hours before the guy turned up

Measured the output of the battery...not sure how but gave me a read out from the tester. He plugged into the socket under passenger footwell but apparently the LR diagnostics software needs vehicle VIN?

He was going to read up online and give me a call. Because the unit wouldn't talk to the diagnostics he said there was little point in going to main dealer and to be honest my bank balance agrees! Just been googling BeCM repairs and doesn't look cheap! May be time to evaluate breaking her...

Pulled all the fuses from both boxes and the relays....the body control one was what identified the issue but couldn't read the diagnostics as the VIN didn't match so wouldn't communicate withe the truck

And can't solve the drain on the 4.0l P38!!! The 2 week old battery is only reading 430amps now rather than 550, there is a 600mAmp drain, no fuse or relay problems, none of his diagnostics would read data from the truck and it would appear it's a body control issue which doesn't sound cheap...

UPDATE: put a voltmeter across the battery without the engine running and was just under 12.5v then started her up and it was reading 13.89v - does this mean it's less likely to be the alternator?

Cool, or not! Thanks for that mate

Maybe a daft question but I'm not mechanically minded or adept; would a failed diode on the alternator cause a drain if the truck isn't being used?

Sorry misunderstood! Will give it a try at the weekend

Unplugged it on the old RF unit before I replaced it but it didn't make any difference :-(

RF receiver from dealer :-(

Cheers guys, noticed the rear heated windscreen doesnt work so will check the relay for that; in the fuse box under the bonnet I think? Don't have a factory fitted CD changer.....were they standard? With the RF receiver changed already can't be that?.. Just been out to check and the alarm...

Cheers guys, have a multimeter but not sure what setting it should be on to test the fuses? Is there any way of checking the diode in the alternator? Please bear in mind I'm a novice!!! Laymans terms are best for me!!!

Hi guys The truck,4ltr petrol, is killing batteries. I've checked that nothing is still lit up at night, changed the RF receiver and at my wits end. Brand new battery reading 11.98v after one day stood and reads 13.98 when running. Checked all the fuses and none are blown. No warning...