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1995-2002 Range Rover P38A
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Hi Brother's 1999 P38 2.5 Diesel has behaved itself for sometime but lately seems to be losing charge. Normally it could stand up to 5-6 days and still fire up - now it seems battery is as flat as the proverbial ie, won't kick over after a couple of days. Have checked the current drain at the battery earth terminals which comes in 0.66 amps. Checked the drain at individual fuses but I don't know if the results are good or bad Can anyone help?? Results are :-
Fuse 1 (instrument pack, clock, radio, centre Console) = 0.2 Amp
Fuse 9 (Front amplifiers, front doors) = 0.1 Amp
Fuse 15 (Courtesy lights, load space light, rear wiper etc) = 0.2 Amp
Fuse 22 (Front doors windows only) = 0.02 Amps
Fuse 29 (Air suspension delay/Timer) = 0.23 Amps
The BECM constant waking up etc when parked hasn't been a problem since Marty_NZ unlocked and checked out the BECM last year.

We were assured by the previous owner that the battery was relatively new when fitted but he also said that it had been regularly service (which could be true if it was serviced every 10 years!!!!! It certainly wasn't done annually)

Any advice or guidance would be most appreciated.
Cheers Mike
 

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How are you checking the current draw as you shouldn't be drawing any current on any circuit except Fuse 1. If the battery was going flat in 5-6 days then it isn't that healthy anyway. Thankfully you are in teh UK so can buy the best upgrade you will ever find, one of these 643/644 Hankook MF31-1000 Heavy Duty Car Battery 12V 115AH. Another owner with a diesel fitted one and reckons he was going to re-register it as a hybrid, if the engine stopped he could still drive it on the starter. I've got one on both my P38s, the spare car can sit for up to a month and still fires up first time.
 

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1999 P38 vogue
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My friend mark got a 2.5 dies hell and his battery would drain over few days ---- he was checking various parts for drain ---- this carried on for days ---- after the 4th call for me to go give a jump start ------ I took his battery and threw it out ---- new battery ---- all works as should
I don't know how many times I said battery fubar
 

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A drain of .66A is way too high, that means 16Ah per day is lost, and the battery is under constant stress. 5-6 days would be a good result with such a drain!
The BECM should draw no more than 0.04A, add a bit for radio etc and you should see a max of 0.1A.

Filip
 

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Get load test done on the battery , Ithought i had similar problem but test showed only 55% power after test , replaced it with a calcium battery
 

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1995-2002 Range Rover P38A
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Discussion Starter #6
Thanks to all for the quick responses.
The draw tests were done using a multimeter connected between battery earth terminal and earth lead. The fuse checks were done using a fuse adaptor connected to the multimeter. All checks were done after BECM went into sleep mode.
A load test was done which showed the battery was OK. Alternator was checked at a local start/charge repair outfity and was OK.

Looks like we're going to have to dig down into the circuits.

Thanks again Mike
 

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1995-2002 Range Rover P38A
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0.66A is about right for a BECM that is awake. Should drop to 12 or 13mA when it goes asleep.
You can leave the bonnet open. Close all the doors, ignition off, measure it and it will drop after 2 minutes.
If it doesn't, then something is keeping it awake.
 

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Pulling and replacing a fuse or a test adaptor might be waking up ECUs. Check out 'humble mechanics best battery drain method' on youtube for a method to read voltage drop at a fuse blade and convert it to a current using tables he links to. (Car locked, 'bonnet/hood open' switch taped down). If you haven't got one already, download the factory Electronic Troubleshooting Manual (ETM) pdf for your model, to see what components are on any one fuse circuit.
 

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1995-2002 Range Rover P38A
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Hi Brother's 1999 P38 2.5 Diesel has behaved itself for sometime but lately seems to be losing charge. Normally it could stand up to 5-6 days and still fire up - now it seems battery is as flat as the proverbial ie, won't kick over after a couple of days. Have checked the current drain at the battery earth terminals which comes in 0.66 amps. Checked the drain at individual fuses but I don't know if the results are good or bad Can anyone help?? Results are :-


The BECM constant waking up etc when parked hasn't been a problem since Marty_NZ unlocked and checked out the BECM last year.

We were assured by the previous owner that the battery was relatively new when fitted but he also said that it had been regularly service (which could be true if it was serviced every 10 years!!!!! It certainly wasn't done annually)

Any advice or guidance would be most appreciated.
Cheers Mike
The problem is the large antenna used to let the car pick up the radio frequency (RF) from key fobs at long range. This is a known problem with an easy fix - disconnect the antenna. Not the car radio antenna. The key fob will still work at closer range.
When they made the cars not so many other vehicles had RF keys and no one had home internet wi-fi routers. These RF signals keep waking up the body control unit which then draws 5 amps a flattens the battery.
Done this on my P38 and had no problems since.
 

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The fob operates on 315 MHz in the US and 433 MHz in the rest of the world, home wi-fi operates at 2400-2480 MHz so wi-fi is NOT a cause of the BeCM being woken up. No idea what else operates on 315 MHz in the US (as the spectrum allocations are different to the rest of the world) but 433 MHz is used for any low power, intermittent operation, devices, so that includes wireless doorbells, weather stations, garage door openers, etc.
 

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1999 P38 vogue
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One thing you could do is unplug wire on remote lock box under trim of rear side window ----- remote won't work as far away but it stops battery drain ---- done it on mine & marks 2.5 there's a vid on YouTube how it's done
 

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I went through the same battery drain problem a couple of years ago. I suspected next doors door bell and/or my weather station, both on 433 MHz.
I had the later mark II receiver so it should have been less prone to interference. I tried disconnecting the aerial as suggested but the battery still drained down.
Eventually bought the latest mark III receiver and no problems since. Only problem is, it is very expensive for what it is.
It is a design fault on the car and should have been covered by a recall.
Marty on here does a filter device which solves the problem and is a lot cheaper.
 

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The fob amplifier wire to unplug is the blue one, under the parcel shelf, below the antenna, to see if that is the problem. Marty's shop 'p38webshop.co.uk' sells a filter to cure this problem inexpensively. and let you keep full remote functionality. He also has a DIY test for the latch microswitches, the other principal cause of battery drain, on his site, and in the 'Info' posts on this forum's first page.
 

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the receiver issue is not specifically 315Mhz or 433Mhz because the RF frontend picks up a much wider band. any data buts (weather stations, garage doors, amateur radio, etc) will trigger the receiver. BECM then gets a burst of unrecognisable data and wakes up.

Marty's filter specifically looks for the LR P38 header in the data, and only sends it to the BECM if valid, so filters all the crap.
 

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Discussion Starter #16
Thanks for all your replies. Round four of the investigation starts this weekend.Now know the alternator is definitely not the problem. Battery condition is still under investigation. Have known about the RF problem for sometime but as stated earlier, after Marty's excellent work on the BECM we have not had a problem with battery drain until the last couple of weeks.And battery condition aside it still doesn't explain the 0.67 amp drain. With regard to "pulling the fuses waking up the BECM"- it didn't wake up for the 30+ other fuses. Also checked out the majority of you tube videos, including the guy with the tables which to be honest as a professional engineer I couldn't make sense or reason of, to me he was confusing milli-amps with milli-ohms.Still - not discounting anything at the moment as we both have been working with Landrovers for years and have learned never to take anything for granted with landrover "technology",
Thanks for your all suggestions, they are appreciated, Cheers Mike
 

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Discussion Starter #17
Problem now resolved hopefully!!!!!! Alternator was rechecked and as part of the check the guy we use for all our start and charge issues up-rated the charging capacity. The RF antenna was disconnected for a week and made no difference to the draining. Using various methods for testing the circuits and a lot of faffing letting the the BECM go to sleep before testing we got down to the only fuse where there was any drain was fuse 1 which was well within the limits. Had the battery checked professionally at three different places showing the battery to be OK. Finally borrowed a piece of kit from a local guy with all gizmos and gadgets for checking the battery and after running the battery through the kit's cycle it found the battery faulty on the level of amps available after load testing.

Now swapped the battery for the one recommended above by Richard G.First try at starting was a disaster as the range rover was dead as a the proverbial.... Checked and replaced all the the earth leads and the beast fired up almost on the first crank. The only issue now is that the damned "ignition key in" warning keeps flashing up and won't go out.

All the fun of running a P38!!!!!!!.

Thanks to all for your help. Cheers Mike
 

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Glad you've got it sorted. The ignition key in warning is set when the microswitch in the bottom of the key slot gets gummed up and doesn't release when you pull the key out. Give it a good squirt of brake cleaner and work the key in and out a few times and it should be OK. Brake cleaner will evaporate and not leave any residue to gum it up again. Easy to check as it will tell you the key is in if the door is open so if the message goes away when you take the key out while the door is open, you've fixed it.
 

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Key in will keep becm awake, as said, brake cleaner, then when nice and dry a squirt of graphite will sort it for years to come
 

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Hi Brother's 1999 P38 2.5 Diesel has behaved itself for sometime but lately seems to be losing charge. Normally it could stand up to 5-6 days and still fire up - now it seems battery is as flat as the proverbial ie, won't kick over after a couple of days. Have checked the current drain at the battery earth terminals which comes in 0.66 amps. Checked the drain at individual fuses but I don't know if the results are good or bad Can anyone help?? Results are :-


The BECM constant waking up etc when parked hasn't been a problem since Marty_NZ unlocked and checked out the BECM last year.

We were assured by the previous owner that the battery was relatively new when fitted but he also said that it had been regularly service (which could be true if it was serviced every 10 years!!!!! It certainly wasn't done annually)

Any advice or guidance would be most appreciated.
Cheers Mike
 
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