P38A Spurious Failure Warnings

Fergie46 said:

Having just entered therapy sessions for my recent BeCM induced ptsd (which are going well, incidentally), I think the culprit could well be the +ve feed to the very same or the unit itself.
Luckily there are wonderful people who can initially test and then repair if necessary. Vehicle wiring diagrams are available on the tinterweb with the attendant masses of info regarding earth locations etc etc.
From the symptoms it's almost like somethings tripping and resetting although why raising the rpm seems to sort things out is strange - it crossed my mind to suggest seeing what happens if you run the vehicle with jump leads connected to another healthy vehicle - two batteries in parallel would smooth out any ripples or abnormalities from the alternator.
Oh, here's nursey with the syringe again - must be that time already.........

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Thanks, made my day.

Of course, you do realise that ptsd stands for post traumatic spending disorder, don't you?

Took her out today and she behaved pretty well.
A few "reset's of doom" as described above but she kept on going.
Now at the moment ...sometimes she will do the "Fuel/Overtemp/SRS" alarm cycle on low idle, and sometimes not. This does stink of earth/power lead glitches/spikes..
Q. Can you run with no Alternator at all for a while to see if its an Alternator/rev-related output problem?
Do I just disconnect the input terminals to the alternator?
If I disconnect the outputs I thought it would "fry" the alternator, so how do I do a "BeCM" on battery only test to see if its the BeCM or the Alternator kicking off the resets? Sorry if this is a dumb question.

In theory I think it would run with no alternator for a bit until the battery gives out but not sure how the BECM will react. It will certainly throw a fault PDQ but then as the battery drains it could do some real nasty things with the alarm and immobiliser. Then there's the overheat if he fan and water pump are not turning. Assuming it doesn't say alternator fault I wouldn't risk it except as a last resort.

Did you do all the tests on the rangerovers.net electrical fault finding guide?

You should never run an alternator disconnected.

Grrrrrr said:

In theory I think it would run with no alternator for a bit until the battery gives out but not sure how the BECM will react. It will certainly throw a fault PDQ but then as the battery drains it could do some real nasty things with the alarm and immobiliser. Then there's the overheat if he fan and water pump are not turning. Assuming it doesn't say alternator fault I wouldn't risk it except as a last resort.

Did you do all the tests on the rangerovers.net electrical fault finding guide?

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Hi Grrrrr.....
I am getting old and thick I think because I could not find it. Do you have a direct link to that section?
Thanks.

wammers said:

You should never run an alternator disconnected.

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That's what I though, thanks for confirming it. I seem to recall that if you disconnect the Output the alternator jacks up the voltage on it's internals and gets very unhappy.
Thanks for confirming it Wammers.

DanClarke said:

Hi Grrrrr.....
I am getting old and thick I think because I could not find it. Do you have a direct link to that section?
Thanks.

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http://www.rangerovers.net/forum/7-...38/28663-info-electrical-troubleshooting.html

Just take the aux belt off. As long as you don't run the engine for too long it will confirm whether the alternator is causing the behaviour.

If EVERYTHING is disconnected from the alternator, it should be OK. But I wouldn't stake my life on it!

Having read each post, I have the feeling that there is a heavy draw sucking the power somehow. Things clicking and beeping tells me they are not getting their fair share of power. The fact the revs going up allows the alternator to provide said power.

So, is it the alternator? An average alternator won't really start providing a "charge" until the RPM's reach around 1400 to 2000 mark.

It could be the actual + wiring from the alternator or perhaps the earthing of the alternator itself. Best thing to do is undo the belt, remove the alternator and clean the mounting points and smear a little vaseline on each part it mounts to. Also, undo the battery leads and check the viability of the + from the alternator output to the battery as it is entirely possible the lead itself is on it's last legs.

I am not convinced the alternator itself is duff.... it sounds as if it's working as it should when it is required to do so. Seems to me the output fromm the battery to the fuse box is spurious.

Doo said:

Having read each post, I have the feeling that there is a heavy draw sucking the power somehow. Things clicking and beeping tells me they are not getting their fair share of power. The fact the revs going up allows the alternator to provide said power.

So, is it the alternator? An average alternator won't really start providing a "charge" until the RPM's reach around 1400 to 2000 mark.

It could be the actual + wiring from the alternator or perhaps the earthing of the alternator itself. Best thing to do is undo the belt, remove the alternator and clean the mounting points and smear a little vaseline on each part it mounts to. Also, undo the battery leads and check the viability of the + from the alternator output to the battery as it is entirely possible the lead itself is on it's last legs.

I am not convinced the alternator itself is duff.... it sounds as if it's working as it should when it is required to do so. Seems to me the output fromm the battery to the fuse box is spurious.

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Hi Doo,
Strangely, the resets are still occurring but getting fewer and fewer. Reinforcing the whole "bad-connection" of either +ve or earth return somewhere.
Needs more investigation for sure.
Thanks for taking the trouble, it is much appreciated.

And today I took her out for a 10 mile run in rush-hour traffic (all stop/start) and idle revs and It did not throw up a single warning lamp or error message!
Interesting that since the battery change-out the MPG is being recalculated and has so far reached a massive 6.9MPG. Lucky me.
As I've measured all of the volts and resistances and come up short (i'm only 5'6") I have taken it to an auto-electrician for him to have a gander at.
He shares a workshop with a guy that works for Jaguar/Landrover so they are going to plug it into some diag-nasty tools and let me know what it says.

Back in the day, when Ford released it's CVH powered Sierra, it was great for a while. But then they seemed to be going through starter motors like a kid goes through nappies.

But, somehow they didn't relate the fact that they were also going through batteries too. The car would become harder & harder to start, so a new battery would be fitted and all would be well....for a while....

Anyway, it turned out that the timing was being adjusted electronically and would advance, but "only" during cranking! This made it really hard for the starter to turn the engine over, ergo the battery would struggle too.

Now my point being, you have fitted a replacement battery, but even though it is marginally better, there seems to still be a struggle going on.

I would be checking the wiring from the battery to the fuse box/alternator and so on, especially, as previously suggested, the earth points.

Have the guy check the resistance from the battery+ to the fuse box and all the earth points. Sounds awfully like a high resistance connection some place under the bonnet

OK friends, my man says the BeCM has been violated by liquids of some description at some point and is definitely "dodgy".
Can anyone recommend a good BeCM repair outfit with a good track-record and a decent turn-around time?
Many thanks in advance.

Rick the pick and irishrover I think are the two main becm gurus on here

would you not try contact cleaner on it first? Might save some money for you?

DanClarke said:

OK friends, my man says the BeCM has been violated by liquids of some description at some point and is definitely "dodgy".
Can anyone recommend a good BeCM repair outfit with a good track-record and a decent turn-around time?
Many thanks in advance.

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That was a thought, but I was hoping it wasn't

I had a tiny problem with a front window and it was "a" single pin at fault. SO either someone dropped a coffee and hasn't thought to mention it, or wet feet on a carpet has taken it's toll

Still, as suggested, try cleaning the different connectors that go into the BECM. Switch cleaner, available from Maplin and the like.

I used all car electrics - guy called Lynton and he's based in Haywards Heath - post it over to him and he turns them around in 24/48 hours and sends them back nextday service. His phone number is 07976 159583.

He certainly seems to know his stuff - google him and see his website. Can't say anymore than I was very pleased with what he did for me.

And the thing is, is that if you know everythings tickety boo in the BeCM divsion it narrows it down when coming to fault finding etc. These things aren't a sealed unit so can get full of damp, spiders etc - like wot mine was.

how did you get on buddy?