Car computer issue
Submitted: Monday, Jan 23, 2006 at 14:41
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Member - Beatit (QLD)
Hi Guys,
I am looking for expert advice. The problem is this, I was working on my car (no not the Nissan) over the weekend and I had to disconnect the battery so that I could tighten the positive connection on the starter motor. All’s
well and I reconnect the battery (hear a peep from the alarm), got in the car to find that everything needs resetting as expected. Take the car for a drive, had an errant that was 250K round trip, and find that the car is running much better than it has been for months (maybe years).
The question is, did I reset the car computer to factory defaults when I disconnected the battery? I presume that there would be any number of uncleared errors and the like and by resetting the computer I have cleared out this luggage as
well. This seemed the most logical explanation I can come up with (a bit like rebooting the old puter when it is playing up).
This interests me because I can see that it could be useful when out in the scrub and the car is being temperamental. I’d like to hope that these black boxes are that simple and need a reboot occasionally to clear the clutter.
Can anyone shed any light on this?
Kind regards
Reply By: Mike Harding - Monday, Jan 23, 2006 at 17:34
Monday, Jan 23, 2006 at 17:34
Can't say with certainty which will be reset and which will not but some variables will be stored in RAM memory which looses it's contents when power is removed and some will be stored in EEPROM memory which retains it's contents across power cycles.
It should do no harm at all to disconnect the battery from time-to-time to force the microprocessor to reinitialise variables and hardware. However some systems "learn" about their environment so it's possible it may have to go through that process again but that shouldn't be an issue – might even be useful.
Keep in mind that modern vehicles don't just have one microprocessor
they may have 10 or 20 of them scattered throughout the vehicle - some
suspension systems, even, have a micro tracking them.
RAM and registers internal to the micro can become corrupt from a number of sources - electrical noise, cosmic particles (I kid you not :), software errors etc so why not give the little devils a full reset every six months or so? Ensure you disconnect the battery for at least one hour, better still overnight because some systems may use a capacitor to retain RAM for an hour or two.
Mike Harding
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