P38A BECM not going to peeps. Anyone got a Faultmate or Nanocom?

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gazcabs

gazcabs

Member
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26
Location
York
Hi folks,

Once again I seem to have a BECM that doesn't want to go to sleep. Car is a 95 DT.

I have the new RF receiver (fitted since 2011) which initially solved all my battery drain problems. Last year I had the same issue (BECM not sleeping) which amazingly cleared itself. All I did was pull fuses one by one and at the very end, it went to sleep (checked with ammeter, pulling about 0.05A).

It's been fine since then but the other week we went to Glasgow on a Friday and left car in car park. Returned on Sunday and whilst all the doors unlocked and ignition came on, wouldn't turn over. Basically RAC said alternator wasn't charging while under load, so bought a new alternator (readings were improved under all conditions) and thought all was well.

After another weekend of not being used it still wouldn't start. Doors unlock but not enough juice to turn over. So, put battery on a full charge then left it to see if battery is goosed. After a couple of days stood it reads 12.61v (so looks fine?). Put it back on car yesterday and checked to see if the BECM was going to sleep.

No chance! After 3 minutes it's still reading 0.56A. Pulled all the fuses again but nothing. Disconnected both the RF receiver and alternator while doing all this to eliminate them. I even pointed the car towards Mecca, prayed and sacrificed a goat............nothing :D

I'm wondering if it's worth sticking it on testbook or other reader that can tell if the BECM inputs are switching off? Does anyone know anyone/where in Yorkshire or surrounding area that I can take it too? Ideally avoiding main dealers.

I'd be willing to pay for people's time if it's there own reader (beer/wine whatever's your poison), just want to find out if this is a DIY fix or if I need to call on the services of Rick-the-pick to test/repair the BECM?

Any help gratefully received.

Gary
 
There was a very early problem with diesels regarding BECM not sleeping causing battery drain. Cured by fitting a resistor across two wires in the OBDII plug. Was in tech bulletins on my old version of RAVE, but lost that when i changed from XP to Windows 7. Do a search for P38 tech bulletins.
 
Thanks Wammers.

I'll have a look in my copy of RAVE tomorrow at work. I think it covers 1995 and I do remember seeing one that covered drain, just not sure if it was BECM related.

Yeah I have seen that page before, thanks. I just don't think mine is going to sleep initially, plus I have the new receiver (and tried it disconnected).

I'm now starting to clutch at straws here, lol.

But still smiling.....
 
Ok, now this is odd.

After posting my last reply I then went to look at the multimeter again.

Bizarrely it was reading 0.03A, asleep it was!

Even tried it again and went to sleep a second time, and a third.

Seriously, I haven't done anything. Took ultrasonic sensor off and tried it with it disconnected, still wouldn't sleep. Plugged it back in but apart from that I haven't really done much. It did this last year around March time......

Odd.
 

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gazcabs said:
Thanks Wammers.

I'll have a look in my copy of RAVE tomorrow at work. I think it covers 1995 and I do remember seeing one that covered drain, just not sure if it was BECM related.

Yeah I have seen that page before, thanks. I just don't think mine is going to sleep initially, plus I have the new receiver (and tried it disconnected).

I'm now starting to clutch at straws here, lol.

But still smiling.....
Click to expand...

As far as i recall problem on early diesels was BECM not sleeping, cure was resistor across two wires on OBDII socket. Cant remember which wires or what resistor. Land rover did a kit to cure it, a fortune for a two penny resistor and a bit of heat shrink tubing.
 
Ah, I think it may have been the fuel flap button.

I noticed it was depressed slightly when it wasn't sleeping and now it is almost flush. I pushed it during testing as I read somewhere that it may get a signal from this.

Obviously does.
 

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gazcabs said:
Ah, I think it may have been the fuel flap button.

I noticed it was depressed slightly when it wasn't sleeping and now it is almost flush. I pushed it during testing as I read somewhere that it may get a signal from this.

Obviously does.
Click to expand...

If the flap switch was depressed and making contact surely the flap would open when ignition was switched off.
 
I don't know if I'm honest.

The only 2 things I touched today were the ultrasonic and the fuel flap. It's just interesting that the button was depressed before, but now isn't, and it's sleeping. Maybe it got stuck down or didn't pop back up fully.....

Regarding the ultrasonic, I only unplugged it and plugged it back in.

With these I wouldn't be surprised what caused it, however unlikely it may sound.....
 
My previous 96 auto wouldnt sleep when I got it just by looking at the park light indicator.
A new battery and it was fine for a while.
Then the book symbol kept randomly appearing on the hevac and the fuse box and relays looked burned.

A battery and a 2nd hand fuse box fixed mine.
 
I'll give you a little test to do. You need your tester & leads long enough to close the bonnet while leads are connected to tester.
0.53ma is at the second stage of sleep. When it drops to 0.01 to 0.05 the becm is asleep but monitoring.
The becm will sleep when all parameters have been met & can take up to 10 mins.
When the amps dropdown to the sleep stage, grab keyfobs from other cars, tv remote etc, & activate them by your vehicle while watching your meter.
The reading with jump back to second stage of appox 0.53ma. If this occurs then it's your RF receiver keeping the becm awake. A very easy test to do.
 
Rick

The car is sleeping now, I can only put it down to the fuel flap button having been slightly depressed (don't ask how). It's now flush and cars sleeping at 0.03A (30mA?). This occurred after I'd messed with the fuel flap button, so maybe it was giving the BECM a signal to stay awake (or partially making contact - like I said, don't ask).

Sat and watched it for about 10-15 mins and stayed asleep the whole time. I might try to simulate the fault again to prove if it was the fuel flap button remaining down, causing it mess with BECM.

The RF receiver is the modified later version, although I did do some readings with this disconnected (fully) and it wasn't going to sleep at all, never mind being woken up.

For now it seems ok (plus I did the 'ignition key in' test and the display now goes blank after 2 mins, followed by the beep when you close the door or wake up the BECM by any other means).

The battery is a Bosch one, it's in one of the images further up. S4, whatever that means.

Thanks for all your input guys.
 
gazcabs said:
Rick

The car is sleeping now, I can only put it down to the fuel flap button having been slightly depressed (don't ask how). It's now flush and cars sleeping at 0.03A (30mA?). This occurred after I'd messed with the fuel flap button, so maybe it was giving the BECM a signal to stay awake (or partially making contact - like I said, don't ask).

Sat and watched it for about 10-15 mins and stayed asleep the whole time. I might try to simulate the fault again to prove if it was the fuel flap button remaining down, causing it mess with BECM.

The RF receiver is the modified later version, although I did do some readings with this disconnected (fully) and it wasn't going to sleep at all, never mind being woken up.

For now it seems ok (plus I did the 'ignition key in' test and the display now goes blank after 2 mins, followed by the beep when you close the door or wake up the BECM by any other means).

The battery is a Bosch one, it's in one of the images further up. S4, whatever that means.

Thanks for all your input guys.
Click to expand...

You made maybe a good shout with the fuel cap release button. Checked mine today. With button pressed then ignition turned off, nothing happens, but there must be a connection to the BECM so maybe causing drain. Nothing happened with fuel cap until button was released and pressed again. :):)
 
Rick-the-Pick said:
Believe it or not, The fuel flap is a known source of drain & keeping the Becm awake.

Not sure how as the motor is just a solinoid.
Click to expand...

There are electronics involved. Switch is a momentary ground of relay 6 to pull actuator but will only do it if ignition is off. With ignition on switch does nothing. As said earlier if switch is kept pressed whilst ignition is turn off nothing happens, so there must be some circuit controlling it. Switch has to be released then pressed again for flap to open, with ignition off flap actuator will then get pulled every time switch is pressed, even with flap already open. So electronics are involved, which you will know more about than i do. If switch is permanently made it must inhibit sleep mode by interfering with the control circuit. ;)
 
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