I was caught out again this week by the BECM waking up when parked and flattening the battery. I guess I could solve the problem once and for all and go out and buy the mk3 receiver but it is very expensive. I have since removed the blue aerial lead again which I had foolishly replaced when refitting a trim panel in the back.
It would be a big help if there was an easier way to see if the BECM is asleep or awake. The led on the auto gear change panel is difficult to see from outside. I am thinking about fitting a more prominent indicator. Maybe a brighter led on the dash.
Where would be a good point to pick up the signal? I thought about the park led on the gear change panel. The circuits would have to be isolated, but how to do it? Need comments from Gilbertd and/or Marty I think.

I am having similar issues right now and I agree the little LED is hard to see from outside a locked truck. Especially in a lit up area.
I'm going to watch this as I would love an LED on the dash to do this function.
I'm was also going to put an LED for the ABS pump and EAS compressor. I know someone has already done the LEDs for the pump and compressor but could not find the info.

I was even thinking of a transmitter (different frequency of course) from the car back to a portable receiver in the house.
A small pocket-sized case with a red LED on the top that I can put on the coffee table. The electronics should be cheap enough from Maplin. Red light comes on when the BECM is awake. How cool would that be.
An air compressor running indicator in the car would be nice. I have already got a pressure gauge fitted inside the car.

Sorry for the delay lads, just back from another of my European 2,000 mile round trips. The diagram doesn't really go into any detail on how the LED is dimmed so no idea whether it is fed with a low voltage or a PWM signal. Pulling it out and sticking a meter across it is about the only way you'd find that out. I don't see why you couldn't hang another LED in parallel with the one that's already there but if you wanted to get really clever, you could use the low voltage (or PWM signal) to switch a transistor and allow that to switch whatever you wanted it to switch.

Marty may have delved into it a bit more but he's away working at the moment.

You could look for clock pulses on the line to the window switch pack.

I'm not sure on the exact way the gearshift indicator works - but I presume it to be PWM as the LED's are dimmed on the range that isn't currently in use - so if you go to low range for example, then the high range markers will go dimmer (especially at night I think when the instrument lights are on). So you could possibly pick up the feed from one of the LED's, and then build something to make that drive a brighter LED.

Also it is worth remembering that especially on the later P38's the door doesn't actually need to be closed for the BECM to go to sleep. So if you are just wanting to stay with it for a bit and see if it's sleeping then you can do it with the door open (or sit in it and close the door - again it doesn't need to be locked - it should still timeout after 2 minutes anyway).

The other thought I have had would be to see about putting a current measuring device on the power line from the battery to the fuse box and then set that to have a trigger point of say 100ma so when it goes above that it turns an LED on. There must be ways of doing it on something like an Arduino with a non-contacting current clamp and then using that to read the draw.

You could look at clock pulses off one of the serial lines - but I haven't delved into them enough to know whether these actually stop when the BECM goes to sleep - I don't think they will as there are serial lines still to the door outstations that must be active when it's asleep so it knows if the key has been turned in the door for example.

If you were wanting to go from the LED in the gear shift, then you will have to do a bit of probing and see how the BECM illuminates that lamp, as it only interfaces with the H gate on a few wires:
White (Pin 2 at H Gate) Power feed from F6
Red/Blue (pin 9) - Illumination (spliced off other interior lamps)
Brown/Yellow (pin 8) - High Range Status - splices to BECM/Autobox ECU/Transfer Case ECU
Brown/Red (pin 11) - Low Range Status - splices to BECM/Autobox ECU/Transfer Case ECU
Yellow/Green (pin 6) MES1 line (to determine Normal/Sport/Manual mode) - splices to BECM/Autobox ECU Works on truth table with MES2
Yellow/Red) (pin 7) MES2 line (to determine Normal/Sport/Manual mode) - splices to BECM/Autobox ECU Works on truth table with MES1
Blue/Green (pin 3) - 'Z' switch from geabox XYZ switch - splices to BECM/Autobox ECU
Blue/Purple (pin 4) - 'Y' switch from geabox XYZ switch - splices to BECM/Autobox ECU
Blue/Black (pin 5) - 'X' switch from geabox XYZ switch - splices to BECM/Autobox ECU

So there are a lot of shared lines with other ECU's aswell, but there must be one of them that the BECM uses to illuminate the 'gear dot' - note the telltale will illuminate next to any gear that is selected - say you left it in drive or neutral, then the BECM will have the glow on that LED - it isn't always the 'park' LED.

Bit more food for thought!

Thanks Marty.

I have a spare center console that is less marked than the one in the car. When the weather is a bit better I plan on swapping them over so I will use the opportunity to investigate the gear change LEDs with a multimeter. I did think about just picking up from the LED wires using an optical isolator or whatever. Then use the signal to just switch another circuit. PWM is equivalent to an analogue signal using digital means is it? Electronics is not really my forte.
I have got a clamp on dc ammeter and I used it on one of the leads from the battery to check the BECM. My car used 0.65 A when awake and after 2 mins it drops to 12 mA even with the bonnet open.

12mA is about normal so it is going to sleep. It might be being woken up regularly which would cause the battery to drain though. PWM is pulse width modulation so basically it is a fast square wave with the on period varying to give different average voltage.

As GilbertD says...

In fact 12mA is very good for it when it's asleep... I think the documentation reckons on about 30mA.
It should quite happily sleep with doors, bonnet etc open... I had one testing on the bench today with nothing but the essentials plugged in, so pretty much every input was showing incorrect as they weren't there, and it still went to sleep on me whilst I was looking up some data on the PC.

I'd have to have a look into a circuit for driving another LED off the gear shift - but the thing with doing it that way, is the LED will illuminate whenever the shifter is in that position (park for example) and the ignition is on.

I seem to remember when I had mine apart to change the LEDs about (changed the colours) that it looked like a few of them were all commoned up in a strange way (I didn't draw the diagram out but it would probably make more sense to me now if I looked at it again!). That being said, you can get 'normal' LEDs which aren't the 'superbright' versions that only draw 1 or 2mA when lit up - so you may even be able to tap one straight off the original one. Failing that, you could probably use the signal to the LED in the shifter as a trigger wire for a transistor, which then drives the additional LED.

The perhaps most annoying thing about the MK3 receiver being so expensive is the fact it actually works... which sounds like a back to front statement, I know - but as much as I loathed to pay nearly £200 for it a few years ago, because there is no reason for it to be that expensive, and also in my eyes, LR knew about the problems BEFORE the P38 production was finished and only released the MK3 in 2005(ish) - it should in my mind have been a recall item or at least discounted item since they knew about the problem and didn't fix it with the MK2 receiver!

Still, as much as paying the money for it went against my thoughts of JLR company greed - it has to be one of the best investments I've made for the RR - as I've travelled so much for work that it often sits 1,2 even 3 weeks at a time outside the house whilst I'm away and every time I come back and she starts up. The real test will be when I'm away out in China working for 8/9 weeks in a couple of months... if she starts up when I get back (on a 4yr old battery aswell) then I'll be a happy man!

I'm not saying rush out and buy one... but if you are planning on keeping the RR for the foreseeable future, then it may be a wise investment - just in not having to deal with flat batteries or having to keep it on trickle charge all the time etc. Either that, or there are loads of advocates on one of the other forums for putting a cheap 433mhz relay in the power feed to the RF receiver, so then you have another fob to switch the power on/off to the receiver, and then the vehicle fob to unlock. I can see the point of it being a cheap fix, but it's too much of a bodge for my liking - plus it's another fob to lose!

Marty

Marty, I understand the BECM on later cars used less power when asleep than earlier cars. Read it somewhere.
You are right. The sensible choice is to buy the Mk3 receiver. I do plan on keeping the car. I have already forked out for the diagnostics and I have a garage full of spares. It just seems so overpriced for what it is. Island4x4 have them at £200 + VAT. Does anyone know a cheaper source?

It is entirely possible the later ones use less - I can't comment on how much my 01 draws as I've never had to do a sleep test on it... I know it was getting woken up so bit the bullet and got new battery and receiver in one go!

The new receiver is horribly overpriced, yes - but I haven't seen them anywhere at better prices than Island 4x4. Occasionally they come up on eBay but they are still around the £150 mark... Ouch...

I hate to think what the dealer price is for one though...

It must be real dark indeed to check that led.
Just for checking I had placed a small ladies handbag mirror to the shifterlever so that I could see it from outside.
Cheap solution if you don't refund the wifes handbag...

You can still check it sitting inside the car, although you do get some funny looks from the neighbours when you are sitting motionless in a car in a parked car at night.

I tested that the BECM went to sleep with a clamp on ammeter and it was OK whilst on my drive. I then needed to park my car across the road and I left it there for a few days and the battery went flat. Could have been anything on 433 MHz : door bells, weather stations. You name it. Must have been something transmitting all the time I think.
As Marty says, the best remedy is to fit the Mk3 receiver. It is a bitter pill to swallow though. I don't like being ripped off.

Weather stations transmit a data burst anything from every minute to every half hour. If you are parked in range of one transmitting every minute the BeCM will never get chance to go to sleep. The other good one, if you are in a rural area with no mains gas, is level senders in heating oil tanks. They should send a burst every couple of hours or so (although not sure why they need to do it that frequently, 1000 litres of oil lasts me almost a year!) but when the battery starts to get low, they'll send a burst every second or so. I'm sure the buggers put out more than the 10mW the LPD licence exemption allows too, as they will go for miles!

Yeah, pretty much everything 433mhz will do it, garage door openers, other vehicle key fobs...

I also don't like being ripped off, but unfortunately it's about the only 'solution' to the problem. I have wondered how easy it would be to modify the older receivers - I have been doing a bit of work into looking at the fobs and the data they send - I am wondering if there is an easy enough way to recognise part of the pattern of the fob transmission and use that as a trigger. I think that is how LR do it with the latest version... But again, haven't been able to investigate it enough to figure it out!

I've been wondering about that myself - there must be some way to match at least the preamble from the key. I don't have enough RR keys to try it with though.

I suppose you could make a receiver coded to one vehicle - the rolling code can't comprise the whole message, surely?

I've managed to capture the RF transmissions from a key onto my laptop via the sound card. I'm also working on trying to capture the transmission on an arduino and then see if that's possibly to do anything with.

I've only tried it with one key, but there is a common pattern in the first part of the transmission on every time you press the button. I might hook all the bits back up again later and then see if the first part of the transmission is the same for every key (I've got at least 7 or 8 different locksets kicking about and most of them have at least one functioning remote..

Might be interesting to compare them... I then just need to figure out how to translate the transmission that's captured into Binary, and then to hex, work out the rolling code table, and then I'd be able to know what the key ID is.. I know it can be done, I have been in touch with someone who's done it about building me a fob checker, so I could read a fob transmission to test them, and then also make sure that the ID the fob is transmitting is within the range of what the BECM is expecting to see.

Might take a few bits with me when I'm away working in China for 9 weeks... if I get bored then I can work on that!

These are the figures I measured when I was trying to isolate a drain:

Open and close front door:

3.0A, then
after 20s 0.68A and
after 2mins 0.13A

Remove fuse 1:

Open and close front door:

1.94A then
after 20s 0.65A and
after 2mins 0.12A

Replace fuse 1:

Open and close front door:

3.0A then
after 20s 0.66A and
after 2mins 0.12A

Fuse 1 was powering a GROM USB / Bluetooth adaptor.

Still seems a bit high though, even with F1 removed...

You should see about 0.03A when it's fully sleeping - 0.12A is still 120mA, which is about 4x what it should be..

Still, a 120mA drain is still going to be a lot less than a woken up BECM, so if the vehicle is used fairly regularly then I doubt you would notice anything!