Yesterday I had a blown indicator bulb, nothing shocking. The audible indicator sounded the fast click-click-click as we know from regular indicators when a bulb has blown and the message 'blown bulb' showed.
Looking outside which one it was I saw the remaining good bulbs were flashing the normal pulses per minute, as obligatory by law. Pretty sophisticated that central brain of ours!

Maybe I am being too picky but if it told me exactly which bulb was gone (and the type of bulb) I might be impressed......
Unfortunately the BeCM remains 'State Of The Ark' to me !

EDIT: Come to think of it I also want it to provide me with Fault Codes without an external box....
even if that meant JLR could not charge me an arm/leg to read/reset them,,
as per their original intention !

You're not too picky at all Dave but not everyone is inclined enough to translate codes into action to be done so that should be useless. At least it told me it was a bulb in front and I am sane enough to know that I pushed the stalk down on that moment so it must be a bulb left front (after a flashy resumee of my own brains).

It may not tell you the type of bulb but it usually does tell you which one. Not sure about indicators but it'll definitely tell you which one if it is a headlight, sidelight, foglight, even a reversing light.

To be fair it will say 'FRONT INDICATOR BULB FAILURE' and the speeded-up click clack will indicated which side...
but perhaps the compromise here is to agree that the BeCM could be considered 'sophisticated' 20 years ago ?

On a more general point though I am quite serious that in these 'techy' days I do expect a car to tell me if there is
a problem - and just what that issue is (reasonably) specifically, not just (deliberately) flash up some "Check Engine"
light so I then have to go to the stealers to find out (and often at huge expense, of course) !

If it were not for BBS 'cracking their secret code' I really wonder many P38's would still exist ?

Oh well, I thought I'd say something nice about the P38...

Ferryman wrote:

Oh well, I thought I'd say something nice about the P38...

Ah, Ok, that's a different matter... Mechanically it is really solid; Electronically though it is like blancmange - or do I mean merigue...!?

Anyway I am sure that we all have our stories about our P38s but quite a few years back I was very impressed when I (accidentally) drove through 3' of water at speed (- thought it was a wet road not a flooded one....); About 20 yards of it - but the car hardly twitched.. excellent...!!

Somewhat later I realised just what would have happened if I had stopped in that 'stream' and the BeCM got wet !!

Oh and my other half will not even drive it - thanks to (too) many 'Key Code Lockout' episodes...

If your other half won't drive it, that's a bonus, mine only ever has problems when I let mine use it,, plus mpg drops drastically when she uses it compared to when I thrash it about

Give it it's due, the BeCM is 20 year old technology and for it's age was very advanced. It's still advanced compared with some current cars (my 2015 model year company Renault doesn't tell me if any of the bulbs are blown or even if the washer reservoir is empty!) but it was a £50k car when new so you'd expect a bit of sophistication. I don't know of any car that will tell you what the fault is rather than just bringing on the Check Engine light. Some will flash it if it is a minor problem and bring it on all the time if more serious but that's about all you are going to get. The only weak point in the electrics is that some of the connectors aren't quite up to the amount of current that is drawn, other than that, it may be complex, but it's pretty well made and, dare I say it, reliable. Try something Italian or French from the same era if you want to know the definition of unreliable.

Well I certainly have to agree with your comments about French/Italian reliability; Many look great but some don't even qualify as 'cars' IMHO !

But, being more serious for a moment, it's not just about blown bulbs (which frankly we should notice anyway... eg. in the dark..) but I would only really consider the BeCM 'sophisticated' if it could be re-programmed to do something different and useful (if necessary) - and top of the list would be an (audible) engine temperature alarm, followed by a CKP failure indicator (although I realise the ECU would have to send that info. to the BeCM) ! ( Plus a few other driver-friendly things,,,)

There is really no reason why a truly sophisticated system could not for instance display more useful data than 'EAS Fault' and 'SRS Fault' /'Airbag fault' and the like... As I said earlier I know this is not meant to help the owner, it is intended to help the stealers..... Obviously (slightly) later full OBD compliance and CANBUS etc are certainly better and much more sophisticated.

Maybe I am too aware of (US) OBD developments but LR however clearly chose to keep the data available to owners to a minimum: There is enough intelligence in the BeCM to do more.. but it's 'a secret'. And we won't 'Save The Planet' by buying new cars just because our old ones have (££) 'secret systems'. After 10 years the manufacturers should make the code freely available/ /Rant Off - but better stop anyway before I start to talk about diesels/evils !!
_

I don't see why there is so much hype about the BECM either... and I've probably dug into them more than most P38 owners... hell, I've got about 2 of the bloody things sitting in the garage, and most of them still work...

I've seen a few random errors/faults but most of them that I've seen that are actually dead are usually due to something external affecting the BECM - like drowning it...

Yes, it's 20 year old technology (probably more than that - it was obviously in the first production vehicles back in late 1994 and something like this isn't just thought up overnight, so from conception/design to building it was probably a couple more years...) but for what it is, it isn't actually THAT scary inside. I had the (dis)pleasure of working on a late Classic a few months ago, and you know what - I'll take a P38 with a BECM any day... everwhere you look in those things, there's another couple of fuses and relays shoved in a corner. At least on a P38 there's only 2 places to look at, and due to the serial links to various outstations (which again, even though there isn't documentation on these and how they work, are pretty reliable unless you actually have a wire fault) mean that the wiring looms are a lot smaller than the anaconda of copper that is wrapped around the under dash area on the classic... sod trying to trace a faulty wire in that!

Yes, it would be lovely to be able to add some new features to the BECM, to add in some functions that over the years of experience of having a P38, we've all found would be useful... like and over temp warning on the dash, or a low coolant alert... And I'm actually pretty sure it would be possible, as I'm sure there are a couple of spare digital input pins on the logic board... the issue is being able to get a copy of the original coding, so that you could write the additions into it, and all of that, before reprogramming the CPU with it... Since there's not even a circuit diagram of the boards, yet alone someone kicking about with a copy of the BECM code, and the software to amend it, we are unfortunately a bit stuck...

I've read a few times about people saying that they will build an arduino to replace the BECM - but so far, I've not seen anyone come close. It sounds like a bit of a minefield when you start looking at how the different systems interact. I have been looking at building a BECM testing station, and even that's a nightmare trying to map out all the inputs/outputs that need to be generated!

I have to say, whoever designed and implemented the BECM did a bloody good job - it's for the most part robust, doesn't seem to have random hissy fits of it's own accord (so the coding must be relatively 'bug free') and has lasted over 20 years with no major component failures either... Good luck with any newer vehicle having the same build quality in 20 years time!

There's a red light that comes on with high engine temperature so if you really wanted an audible alarm just hang a sounder across the light. CKP is a bit more complicated as without a signal from the CKP the ECU doesn't know the engine is actually turning. I suppose it could be arranged to bring up an indication if there is no signal from the CKP but there is from the cam sensor. There's a world of difference between OBD as mandated in the US to what is needed here. If you read through RAVE there's numerous failures that will light the MIL on a NAS version car that don't on ours (at least on the P38 anyway) but the OBD standard became compulsory in the US from 1996 but not over here until 2000 (or 2003 for a diseasal).

The generic faults such as EAS, ABS and SRS faults are no less what you would find on any other modern car. All require you to take the car to your main dealer to see what the actual problem is. They have to assume that the average owner is incapable of dealing with anything hence the consult your dealer. If the information given was more specific, they could leave themselves wide open to being sued after someone tried to fix a fault themselves when they weren't capable of doing it.

Agree totally with Marty on the later Classics. I had a 93 Vogue LSE so it had every option going. That had a wiring loom that probably dated back to the original Classic in the early 70's. As more bits were fitted, more bits were tacked on anywhere they could find space so there are relays and fuses in just about every bit of spare space. Under both front seats, behind the kick panels, behind the dash, you name it, anywhere they could find room to fit them. The P38 is beautifully simple in comparison.

As for longevity, Misubishi produced ECU's for their own cars, Suzuki and Toyota. They used cheap electrolytic capacitors that burst resulting in no sparks. This affected virtually all models from 3 manufacturers from the early 80's up until the mid 90's. I've replaced the caps in a couple of Suzuki ECUs that has bought them back to life after the owner had been told that their only option was a new ECU at £600. That isn't worth it most of the time as that is probably about what the car is worth. I've seen, and nearly bought before having second thoughts, things like Misubishi 3000GTOs that are being sold as non runners with an ignition fault. If the ECU can't be repaired then it's new ECU time, unless the car is an import (as many are), then an EU spec ECU won't fit so the car is scrap.

Martyuk wrote:

Yes, it would be lovely to be able to add some new features to the BECM, to add in some functions that over the years of experience of having a P38, we've all found would be useful... like and over temp warning on the dash, or a low coolant alert... And I'm actually pretty sure it would be possible, as I'm sure there are a couple of spare digital input pins on the logic board... the issue is being able to get a copy of the original coding, so that you could write the additions into it, and all of that, before reprogramming the CPU with it... Since there's not even a circuit diagram of the boards, yet alone someone kicking about with a copy of the BECM code, and the software to amend it, we are unfortunately a bit stuck...

What's the processor used in them, and how big a ROM does it have? It can't be that hard to disassemble it...

gordonjcp wrote:

Martyuk wrote:

Yes, it would be lovely to be able to add some new features to the BECM, to add in some functions that over the years of experience of having a P38, we've all found would be useful... like and over temp warning on the dash, or a low coolant alert... And I'm actually pretty sure it would be possible, as I'm sure there are a couple of spare digital input pins on the logic board... the issue is being able to get a copy of the original coding, so that you could write the additions into it, and all of that, before reprogramming the CPU with it... Since there's not even a circuit diagram of the boards, yet alone someone kicking about with a copy of the BECM code, and the software to amend it, we are unfortunately a bit stuck...

What's the processor used in them, and how big a ROM does it have? It can't be that hard to disassemble it...

Uses a Motorola MH68C11KA series MCU. Runs at 3MHz from memory, and has 640 bytes of EEPROM (Which is party used for the vehicle ID/specifications... and I've managed to decode all the bytes of info that relates to vehicle settings etc. There are other bytes of EEPROM used, but no idea what for!

The datasheets I have shows 24K of OTPROM for the version that I think the BECM uses..

Would you mind sharing some of that info Marty? I've written something to dump the EEPROM from the BECM but haven't gotten around to decoding any of the info yet as I'd have to stick it in the car, change each setting, read it again and look for the difference - that's the hardest part! I'm hoping to make something cheap to reprogram BECMs.

I was interested in reprogramming the Motorola on the board by replacing it with a non OTP chip but I'm guessing that quite a lot of the logic is also located in the gate-array chip next to it. Out of curiosity have you had a look to see what that chip is actually controlling?

Hmmm, so you'd need to get the chip decapped or find some way of reading out the OTP. I wonder if it's a flavour of HC11 that can be made to boot from an external ROM, and then flipped back to its "own" ROM, or for that matter if arbitrary code can be uploaded to it. That way it might be possible to upload something to RAM, jump to it, and read out the contents of the ROM.

Edit: It wouldn't be 68HC11K4 would it, and not KA? That's got certain implications for how you'd talk to the chip.

I've not tried reading the ROM but yes you can put it into bootstrap mode. From there you send your program to it via serial and it will run. I might see if I can read the ROM later...

The one I have is a KA4.

So KA suggests that it hasn't got a lock bit. I'd be really interested to see if you can suck the ROM image out of it.

Interesting discussion.... but again I would suspect the usual 'Reverse Engineering' problem here: Not just getting the Code off the chips but interpreting it accurately enough to modify it (?). Serious point though - is it worth us asking LR as a 'group of enthusiasts' etc for some (really) useful 'secret' BeCM info ? If their T4 is no longer about it would seem like a very reasonable request....