I *so* thought I'd have to admit some of you were right...

.... when the 'door open' light refused to turn off and therefore the central
locking on the Alfa failed after a mere 90 miles today....

But then I found that the boot light wasn't in properly and it was shorting.

Popped the unit back in properly and all is well.

Anybody care to try to explain how a popped out boot light unit can cause
the onboard pooter thingy to think that a door is open????

Dave

 

"Wired up by Italians."

HTH

 

Courtesy lights'll be on the same circuit the pooter checks maybe, cos the
doors also activate a courtesy light switch when they're open.

Maybe

If it's just a single warning light rather than a little diagram of the
car showing which door is open, prolly isn't anything very clever that
needs the pooter anyway.

Mebbe.

 

Simple: The light on the dash is ignited when the circuit relating to it,
has power flowing through it.

On some cars, the way it works is, each door / boot switch will have a wire
run to it on the side of the switch that is 'closed' when power isn't run to
it, in addition to the wire that when a full circuit is made by the door /
bootlid being opened, feeds power onto the circuit which feeds power to the
bulb in the light in question... so, when you open the appropriate orifice,
as well as the connection made sending power up the wire that goes to the
light in question, it also sends a current into the circuit that ignites the
light on the dash... so if you've had a short that's allowed power to light
up the boot light, it's powered the warning light circuit as well.

Or something like that.

HTH... although it has probably confused you more! ;-)

 

WavyDavy emerged from their own little world to say

Probably using a CAN bus [1]. The new BMW R1200GS has one which is causing
all sorts of weird electrical faults.

They were used on Xerox products when I worked for them. Great in theory as
manufacturing costs are reduced. In practice we had endless firmware
revisions due to piss poor R&D.

[1] http://www.embedded.com/showArticle.jhtml?articleID=13000304

 

WavyDavy says...

It's an Alfa, anything is possible with the electrics.

 

jack hackett says...

Commonly known as having the interior lighting 'positively switched'.
It's standard on most cars.

 

How many doors has it got?

 

Sounds like a good theory to me.. Esp when added to Ginge's theory...

Welll yes, I are tight[1], so no 'pooter display, just a door warning. But
it wouldn't be able to tell me which door, anyway, would it, if it was the
boot light...

Dave

[1] It seems to be very good at saying "Alfa Romeo" and what the temperature
is and what door is currently wide open and going ';bing' when you exceed a
pre-set speed and can't be arsed to look at the speedo. Apart from that I
couldn't see why I should pay extra £££s for the 'pooter display...

 

My old BX had a display which had seperate warning lights for each door
*and* one for the hatchback.

Always a good source for miles of spare wiring are dead BX's

 

That was going to be my answer too, and I worked with them for 6 years.

 

WavyDavy was seen penning the following ode to ... whatever:

Luigi was too busy snogging the boss's secretary to take much care
with the wiring.

 

That sums up SteveH's problems in a nutshell.

 

It's an Alfa. It'll be growing new doors all the time ...

 

Bugger.

 

<snort> is it really *that* obvious how much I like them? ;-)

 

I was unable to switch off the instrument illumination
on the bimmer the other night - **** knows how that
happened! I was turning the lights between on and off
and the clocks stayed lit. It was only when I switched
the ignition back on then off that it went out.

It wouldn't be so bad if it was the old one but this
was on the 18 month old!

 

I was asking about the family engine sized BMW.

 

Short for 'alf a plug short of a wiring loom