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Member
Joined: Feb 11 2018
Posts: 151

Hi,

I'm having issues with my P38. I believe its the BeCM that is causing issues.

Listed are some of the problems
Message center saying Electrical Fault
Rear wiper not working.
Front wiper only working on constant and not self parking.
Headlights on permanently when ignition on
Mainbeam not working
Interior lights not working
Telltale on Cruise Control, Hazard Lights, Fog Lights and EAS not working.
Sidelights not working
Rear door CL dont work nor the front. I know rear are driven direct from BeCM

I had a few random messages over last few weeks such as
Alternator fault
Interior Lights Disabled
Interior Lights Enabled

Engine can be started
EAS works
HVAC works

I've checked all the wires and connections for damage and see no damage in the engine fusebox.

Does that sound like the BeCM?

Many thanks

Last post was done using mobile. Ive had more time with laptop today.

Member
Joined: Jan 07 2016
Posts: 96

Nope.
Sounds like a major earth fault and/ or a super screwed up fuse board under the bonnet.
What seemingly innocent thing did you do just before things started acting up? Wash the car? Drive through a puddle? rainy day? Change battery?
Has water gotten to the under bonnet fuse box? You will not necessarily see the damage as it would be under the top cover on the PC board.
Have you unplugged and checked all of the many plugs on the Becm for corrosion? Just a bit of liquid on the plugs will cause it to go totally berserk!
Have you run the electrical checks posted on the dark side forum (.net) ??
Spend some quality time under the RH seat and report back.........

EDIT:
Just read your other thread......"There is also a burning smell in fusebox"...............Hmmmmmmm.........Possibly a good place to start? All of the above still applies.....
BTW. The only "watertight" plugs are the ones under the fusebox....and they will hold any water that comes in from the non watertight lid very effectively. Fizzzvrrrzzzttt!

Member
Joined: Apr 23 2019
Posts: 190

The lights on without the switch could be an earth thing (ie going with Bolt's conclusion) - but could you just define the difference between main beam and headlights, since you say the first doesn't work and the second is always on?

Member
Joined: Feb 11 2018
Posts: 151

Thanks guys,

Headlight low beam is on permanently regardless of switch position.
Main beam does not work at all. Won't flash or stay on main beam.

The BeCM is bone dry and ive had the connectors out and all look clean.

I did do a coolant change with water pump and thermostat not long before. I dont recall getting any cooland around there.
I did use a pressure washer under the bonnet but only around the other side of engine to get some oil off the engine mount.

I do have the usual problem of wet pollen filter and leak, but thats other side too.

Member
Joined: Feb 11 2018
Posts: 151

PS,

Ive got a second hand fusebox on order to test.
Should be here by friday.
Looks like I'm using Shanks' Pony for a while :(

Member
Joined: Apr 23 2019
Posts: 190

E252 RH footwell panel - that's the earth point for most of what you say is playing up, although it is common to a few other things, like fuel filler cap. ETM Z5 view 56

Member
Joined: Feb 11 2018
Posts: 151

romanrob wrote:

E252 RH footwell panel - that's the earth point for most of what you say is playing up, although it is common to a few other things, like fuel filler cap. ETM Z5 view 56

It looks OK, although I haven't unscrewed it. The fuel filler cap works btw.

I'm going to have another look tomorrow and try tracing the earth point more closely.

Member
Joined: Jan 07 2016
Posts: 96

Ahhhh........
So, lots of water splashing about, added to an old fusebox with a cover that probably has 1 or 2 clips left and a dried out seal on the lid.....
I killed a slightly dodgy old one on the Borrego doing an waterpump as well.....It only takes a couple of drops getting in to destroy it and cause the types of gremlins you mention. very easy to do when filling coolant.
With luck that will be it, and you can pootle on happily!
Oh, be sure you are getting the correct fusebox as i believe the diesel version is it's own critter.....(No diesels over on this side of the ditch.)

Member
Joined: Feb 11 2018
Posts: 151

Believe it or not, the cover has all four clips still on it :)
Yep got correct one coming. I've got a copy of lr original parts catalogue that uses VIN number.

Member
Joined: Feb 11 2018
Posts: 151

Well, it's also draining battery. It's now indoors recharging.

Member
Joined: Dec 30 2015
Posts: 1096

I saw your PM on here.. and sorry I haven't got back to your email yet... Away working again and my schedule has been hectic.

Today is a long day, but I'll look into it more thoroughly as soon as I can, but it does look like it could be an issue in the BECM on at least the power board. Which luckily it's easy enough to check and replace if needed...

I'll be in touch/reply to your email as soon as I can.

Member
Joined: Feb 11 2018
Posts: 151

Thanks marty

Member
Joined: Feb 11 2018
Posts: 151

Well, ive put the battery on charge for last couple of days and refitted it today.
No error messages

Yet!!!!

My battery does not seem to be taking a full charge according to my charger.

It was a new Exide battery in February 2018

Member
Joined: Jan 07 2016
Posts: 96

Remember:
With batteries in these days of "Build it down to a price point, not up to a spec"........"New" does not necessarily equal "Good"
Have it load tested with a proper resistive load bank tester if possible (Not one of the pocket digital jobs!)

Member
Joined: Feb 11 2018
Posts: 151

Yeah, it's not just batteries.
I've now got to plumb in a new plug in the bathroom sink. It lasted just over a year. Ffs

Any ideas where I can get it tested?

Member
Joined: Feb 11 2018
Posts: 151

And no, I don't mean the sink lol

Member
Joined: Jan 16 2017
Posts: 533

Usually somewhere that sells batteries will have a tester, though you'd want somewhere you could trust not to try and fob you off with a new battery anyway.

Member
Joined: Jan 07 2016
Posts: 96

Being in California.........not really.....(Sorry to hear about the untimely end to your cheep sink drain)
What I can recommend is going to an old battery shop with a bunch of grey haired battery anoraks in residence......
They will probably have a real battery load bank out the back. Probably designed and built in the early part of the last century.....
Sort of like some of us! This is a tester that needs a cart, has huge leads, and usually a big rheostat to turn up the load and a
couple of meters to tell you what is up! It would not look at all out of place in an old Frankenstein movie.
(The tester that is, not some of us!.....well....maybe some.....)
The small handhelds which put a tiny load on the battery and extrapolate its Cca and reserve are just too easy to fool.
I have seen up to a 50% error rate with them in both directions.......They do look cool tho' and some will even spit out a little ticket
telling you a fairy tale about your battery....
To be slightly fair, when they do happen to guess correctly, they are pretty good at it.

Member
Joined: Feb 11 2018
Posts: 151

Well battery was reading 12.6v this afternoon and still no problems.
Started easily.
Double checked the voltage drops too. All seem to be in parameters.
I've got the second fusebox here which, I will hopefully, fit tomorrow afternoon.

Electricary is really annoying :(

Member
Joined: Feb 11 2018
Posts: 151

Just an update.

It seems to be behaving now. Not had a problem sinc emy last post, although I do think the battery might be slowly on its way out.
Its reading 12.5v in the morning. Am keeping an eye on it. I bought a cigar lighter voltage reader for £3.60 delivered. It reads the same as my VM at the battery.

The fusebox I bought, had a burned out fan relay and board under it. So much for being tested.
Sent it back for full refund.

I also fitted a new new voltage regulator and brushes to a spare alternator I have and changed it last week. Its now reading 14.2 v at idle.
I think the setpoint for these BMW engines was set at 13.9v which was fine for older batteries with less calcium in them.

This is the part i used if it helps anyone.

https://www.buycarparts.co.uk/era/7989921