RE: Troublesome onboard computer on 1991 325i

["Fadeev, Alex" <Alex.Fadeev@xxxxxxxxxxxxxx>]

> I have a 1991 model 325i with an onboard computer that is not
> working properly. Pressing the buttons for speed, consumption
> or distance measurement does not work - it goes into the mode
> but the readings stay zeroed. If I set the speed limit to say
> 130kmph, funny enough the gong works.

Rudolf,
	Your OBC gets the speed readings, but does it get the fuel level
feed? Actually, with the speed feed it should display the average MPH that
you say is not working. But before we pronounce the OBC dead, double check
that the OBC harness is in fact plugged in tight to the back of the
instrument cluster (big blue plug). Also make sure that the OBC itself is
plugged tightly into the said harness. You can get access to the back of the
OBC by going through the glove box.

> The other functions such as the temperature sensor, date and
> time also work. A friend's 325i (1990) has functions to display 
> the version of software and the amount of fuel in the tank, 
> which mine either does not have or is also malfunctioning.

You and your friend have identical OBC's. 
Press 1 and 1000 simultaneously to get the fuel in liters and 1 and 100 to
get the OBC plug code (could be the other way around). The functions should
all work iff the OBC itself is OK.

> Another problem is the if the car is double locked 
> (dead-lock), one can still unlock the passenger side door
> and boot, so it seems to be malfunctioning as well.

To double lock you need to turn the lock cylinder full 90 degrees. Once you
complete the turn the mechanical double locking will be enabled. If that is
not happening, most likely your driver side lock cylinder is toast. Dealer
sells replacement lock cylinders for around $30 that can be easily codes to
work with your key. More on this and many other questions you haven't asked
yet at the FAQ (section 7): http://cbsgi1.bu.edu/bmw/new_bmw.html

> Questions:
> 2) Are the two problem areas perhaps related ?

not.

> 3) Does anybody have any upgrade software that one can 
> perhaps program into the old CPU?

You give BMW and early 80's electronics too much credit. The OBC does have a
coding plug that identifies was car model's inputs. That version of the plug
is displayed by pressing 1 and 100 (or 1000). But even if you have a wrong
coding plug the OBC would still work, just skew the readings.

good luck,
alex

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