[q-rover]

:x
Found out something was wrong tuesday morning, when, after having driven the car on sunday,
it wouldn't start due to low battery.
Yesterday did some simple fault searching and have concluded the BECM isn't going to sleep.

What could cause this, and how do I continue searching for faults?
Most of the relevant topics I've found on this subject seem to focus around the
problem of the BECM sleeping then being woken up by errant/ stray signals.

I've concluded mine doesn't go to sleep, the light by the gearselector doesn't go out
even after 5 mins, locked, unlocked, remote arial connected, disconnected.

Help. I have no experience with electrical/ electronic faults and can just about use a multimeter
to see what voltage the battery has.

 

[996TURBO]

Hi Quentin,

Do you have the late type RF receiver Ref : YWY500170

If you don't, upgrade yours.

That's the 1st cause of non sleeping BECM

Cheers

Flo

 

[q-rover]

How do I find out which receiver I have?
There are no markings on it, or part no.
Simply by a new one and fit it?

 

[allyv8]

If I read your first post correctly,you say it will not sleep - even with the remote aerial disconnected.Fitting the upgrade is not going to help then.Is the car fitted with any aftermarket electrical kit ?

 

[q-rover]

No aftermarket wiring or scotchlocks. I have intended fitting the light harnes
and extra lights, but that is still in the project phase.
I can't think of anything that I did between say saturday and tuesday
that could have upset the electrical system, either.

 

[nipper]

How do I find out which receiver I have?
There are no markings on it, or part no.
Simply by a new one and fit it?

If you check out my posts and find the one where I asked the same question you will find that someone posted a picture showing the internals of the different types. You have to open the receiver up to see.

 

[allyv8]

If you are sure there are no "aftermarket accessories" that could be keeping the BECM awake it may well pay to stick it on Testbook to do a sleep test,this gives a 0 or 1 answer to all the inputs that mean the BECM should be happy to shut down.I rarely use it as 99% of the time the problem is a dodgy Tracker/phone kits/aftermarket music sytems/LPG ecu's etc.Or just the poor original RF receiver.

 

[q-rover]

Right just done some more testing. I was lent a ammeter from a colleague at work
(clamps round the wire) and as he is a electrical engineer (with a P38) :dance: told me
what to test and how.
Put the meter around the main supply going to the fusebox and switched it on.
Then opened a door, jumps up to over 2A draw and more as the EAS levels out
when I close the door. steadies at 1.8A draw after the interior lights go out.
After about another 15-30sec the A draw drops to between 0.6- 0-8A depending
on how many times I do this.

This would indicate the BECM is sleeping? And that there is something else leaking
electricity?

 

[allyv8]

No,its not sleeping,thats just the second stage of shutdown.When its asleep it should be 0.020-0.030A, so something is going on there.You say the gear position idicator still glows so this is a good sign the Becm is still awake, not some other current draw.To save hours of fruitless fiddling as I suggested before the Testbook sleep test is probably the best way forward.

 

[996TURBO]

Allyv8,

Does the environment where you Testbook it as importance on the test?
I mean a P38 could go asleep in a garage for the test and not at the owner's house.
Please tell me your knowledge on this because i've never used this functionnality of the Testbook since i have the later type RF receiver and no problems at all...in that area (but blend motors are coming...))

 

[q-rover]

Just found this.

BECM Sleep Test
This test will determine if the BECM goes to sleep properly or it will stay awake.

1. Sit in the vehicle in the driver seat with all the doors closed.
2. Wait until the interior light switches off.
3. Switch on the ignition.
4. Switch off the ignition.
5. Open the driver door and leave the door open for the reminder of the test.
6. Switch off the interior lights by pressing the button for 4 seconds. On the message centre you can observer the message "Lights off".
7. The message centre displays "Ignition key in" for approximately 2 minutes.
8. If the display goes blank after the two minutes, then the BECM is gone to sleep, if the display is still on, then the BECM did not go to sleep.

I'll give that a try.

 

[allyv8]

Allyv8,

Does the environment where you Testbook it as importance on the test?
I mean a P38 could go asleep in a garage for the test and not at the owner's house.
Please tell me your knowledge on this because i've never used this functionnality of the Testbook since i have the later type RF receiver and no problems at all...in that area (but blend motors are coming...))

Exactly,my workshop is in a remote area with no external RF activity,most P38's will happily sleep there.In the past I've had to go to customers houses to prove to them why their battery is going flat after I have shown them it asleep at my workshop or the garage that got stuck with it.They often grudgingly acknowledged the situation and stunped up for a new RF receiver.(Never an apology tho :roll: )
I cant remember all the switch states that are checked in a sleep test,I have a couple of P38's rusting away at my yard waiting for repairs.If I can get one of them to go tomorrow I'll list what they all are.Its a while since I had a P38 in with battery drain,I see less and less of them now as so many have been scrapped,even Discovery II's are dropping like flies.

 

[allyv8]

Ok,I managed to get one of them to go,the other had a paddy and is in keycode lockout - I'll let that one carry on rusting and sulk for a few days.
The Becm looks and the switch states and gives a 0 or 1 state for the following;
Bonnet open
Rear Lh door open
Ultrasonic input
Sidelights
Head flash
Hazard switch
Fuel flap switch
Horn switch
Ignition 1
Ignition 2
Courtesy lamp
Rear Rh door open
Tailgate open
Flh door open
Flh cdl switch
Flh key switch
Frh door open
Frh cdl switch
Frh key switch
As you can see its a useful list, that is as the Becm sees it,and can save hours of legwork with a multimeter - even more important now than 5yrs ago with the first question now being - Is it worth fixing,I dont want to spend much money on it.( Everone being focused on the "Scrappage" value of £2000 )

 

[Peter Sanders]

Hi

You say the gear position idicator still glows so this is a good sign the Becm is still awake

FWIW The gear position indicator is designed to glow very dim, almost invisible to indicate that the BECM is asleep but IS functioning i.e. working correctly.

 

[nipper]

Hi


FWIW The gear position indicator is designed to glow very dim, almost invisible to indicate that the BECM is asleep but IS functioning i.e. working correctly.

As far as I'm aware when the light is glowing the BECM is awake! When asleep there is no light at all.

 

[Peter Sanders]

Hi

I read about the VERY dim glow of the gear position indicator light somewhere. I am reasonably sure its actually in the owners manual. I had a quick look for the info before I posted the last message, but did not find the reference.

The light really is so dim that it is only a VERY faint glow when viewed in the dark and (on my P38) only just visible during the day when cupped hands surround the area. Apparently if the light is NOT glowing there is a problem/fault.

 

[nipper]

Hi

I read about the VERY dim glow of the gear position indicator light somewhere. I am reasonably sure its actually in the owners manual. I had a quick look for the info before I posted the last message, but did not find the reference.

The light really is so dim that it is only a VERY faint glow when viewed in the dark and (on my P38) only just visible during the day when cupped hands surround the area. Apparently if the light is NOT glowing there is a problem/fault.

BECM sleeping -- No light definately.

 

[q-rover]

Having done some more measuring, I have another question for the
electrickery specialists.
Would a drain of 3.2A on the largish red wire to the alternator keep the
BECM awake, and does it mean the alternator is poopooed?

This was on a vehicle that was completely shutoff, no doors open, just the bonnet.
My battery charger was disconnected when measuring.

 

[allyv8]

Yes,you have an alternator problem ! 3.2A is way more than the 1.1A taken by the BECM when fully awake.Try disconnecting the alt and seeing what drain you get then.

 

[q-rover]

Just done the sleep test with the alt disconnected.
Failed with the main + feed disconnected
Failed with both + and the smaller wire disconnected.
Just thought though that I had the bonnet open all the time,
would this have made a difference?

Am now at a loss, and unlike the UK there isn't a LR 'specialist'
on every street corner, so am loathed to take the vehicle to a
garage that doesn't have LR experience, to get charged £70+/ hour
for fault finding and pot luck part swapping.