P38A Electrickery drain,where am I going wrong?

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The document I have (from some guys investigation of the issue) says it should drop to 0.02 of an Amp after everything is asleep.
That's 2 one-hundredths of an Amp so in fifty-hours it would pull an Amp.
For a 100AH battery (if fitted) that's a long time to discharge >100 days?
 
The document I have (from some guys investigation of the issue) says it should drop to 0.02 of an Amp after everything is asleep.
That's 2 one-hundredths of an Amp so in fifty-hours it would pull an Amp.
For a 100AH battery (if fitted) that's a long time to discharge >100 days?
So even at its lowest reading of 0.16 its still way over the minimum it should be
 
@tomcat59alan Can you confirm that you have put a jog-unit in the RF receiver path to ensure it is switched off when you don't want to use the car?
Or, have you forked out the £300+ for the uprated receiver?
I ask because I found that even with the RF receiver's aerial lead disconnected the neighbourhood was so alive with wireless signals that it would still wake the BeCM up all the time.
So the "remove the aerial" tweak is not a guaranteed fix.
 
@tomcat59alan Can you confirm that you have put a jog-unit in the RF receiver path to ensure it is switched off when you don't want to use the car?
Or, have you forked out the £300+ for the uprated receiver?
I ask because I found that even with the RF receiver's aerial lead disconnected the neighbourhood was so alive with wireless signals that it would still wake the BeCM up all the time.
So the "remove the aerial" tweak is not a guaranteed fix.
Hi Dan, yes I've had a jog switch fitted for years.it's fitted in the wire between the rf receiver and the becm.I was wondering wether to reinstate that circuit and put it in the positive supply to the rf receiver in case it's still being activated by spurious signals even though it cannot send anything to the becm
 
From memory, the fully asleep state should be around 20mA which is 0.02amps.
Most basic multimeters won't be very accurate at reading that current if you are on the amps range
You ideally need an accurate clamp meter.
That said 160mA is 8 times the normal sleep current.
Is the LED on the selector going off?
 
Hmmmm...... My "Jog" is in the Earth wire to the RF unit. Not either of the other 2. So the RF unit just cannot draw power at all, and if not powered it cannot send anything either.
I expect it matters not which side of the RF unit you put it (+12v or Earth) as long as it cannot draw power and try to switch the BeCM on.
I saw a post (maybe from @martyuk that listed all the inputs that could wake the BeCM up.
 
From memory, the fully asleep state should be around 20mA which is 0.02amps.
Most basic multimeters won't be very accurate at reading that current if you are on the amps range
You ideally need an accurate clamp meter.
That said 160mA is 8 times the normal sleep current.
Is the LED on the selector going off?
Selector led? I take it you mean on an auto. Mine's a manual.;) what confused me was why the drain increased when I pulled fuse 33
 
I suspect (but do not know for sure) that the dying OBD2 circuits spiked when you pulled the Diag fuse (33?) and "woke" the BeCM if it was asleep, as the OBD2 subsystem and circuitry is used to interact with the BeCM.
@martyuk will probably have some valuable input on this.
 

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From RAVE:

"The BeCM has two modes of operation; activation
mode or sleep mode. A number of inputs to the BeCM
will change the state of the BeCM from sleep to
activation mode. Sleep mode is required to avoid
excessive drain on the vehicle battery when the
vehicle is not being used.
Sleep mode is entered when certain timers have
’timed out’ (i.e. courtesy lights go off) and all activation
inputs have been inactive for more than two minutes.
If the vehicle is unlocked in sleep mode, the current
used by the BeCM is 30 mA. If the vehicle alarm is
armed in sleep mode, the current used by the BeCM
increases to 40 mA.
When an activation input is sensed and the BeCM
’wakes up’, the current used by the BeCM increases
to approximately 1 Amp."

So should be drawing 0.03 to 0.04A. On the other hand, 1A should be pretty darn obvious! So I reckon the BECM is sleeping but something else is draining it. That leaves the fuses under the bonnet or the fuses under the seat.
 
Looking at RAVE, F33 is the data link connector but also the battery backed up alarm sounder on later models. How old is this car?

The connectors C102 and C202 are behind the right-hand trim panel so guess it might be worth checking those for corrosion?
 
Sorry guys - just seen I've been tagged in this a couple of times! I'm away working at the moment (12-14 hour days onsite, plus travel etc etc etc) so not had much spare time at all to get onto forums/catch up on emails etc.

I get home tomorrow for all of a day before I fly out silly early on Friday for a couple of weeks for the next job! But I'll try and get to writing something more useful tomorrow when I'm home (though have a rush BECM alarm reset/reprogram/test/ship back to get done too!)

Yes, BECM sleep draw should be about 30-40mA. Even 160mA is more than normal, as it's 4x what is standard. I'm hesitant to say it's a BECM issue that's causing it (not ruling it out though...) as most of the ones I've seen where the BECM is at fault is that it draws somewhere around 500mA

The BBUS could be causing a bit more of a drain.. the batteries in them do fail over the numbers of years they have been there, so could be causing something to go awry.
Read briefly about the extra rf receiver, and it shouldn't matter what wire this is connected to - whether it be power, ground, or even the data line - if it's physically disconnecting it with a relay, then it shouldn't be causing the BECM to stay away/wake up.

I believe the stock RF receiver is somewhere around 4mA current draw. Had one on the meter recently on the bench as myself and another owner are working on an inline device to plug and play and hopefully do the same as what the Gen3 receiver does - but at a significantly cheaper price. Have a couple of things in the pipeline, but assuming we can make a working prototype - the next step will be to try and make it so it draws as little current as possible, so it's not then causing too much extra drain!

I'll try and have a proper read through the thread again tomorrow when I'm home and see if there's any other observations I have.... and I'll try to dig out the list of activation inputs to the BECM and post that up too... though if the BECM was being woken up, I'd be expecting a higher current draw.

Marty
 
Nice coloured motor. Pity the drain has turned it into an expensive lawn ornament. More hassle than it is worth really ... might as well donate it to another member to leave outside his house for spare parts ...
 
Thanks Dan, very similar to how I've got mine wired except I have the wire to the becm switched by the jog switch.
 
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