How to get data from wires
marmalade wrote 10/18/2021 at 04:35 • 0 pointsThis is a weird question, and I don't really even have the prerequisite knowledge to ask it properly, but basically, I would like to mess with my car's (E30) OBC (On Board Computer). I found a PDF (https://www.millerperformancecars.com/files/bmw%20electrical%20manual/1989%20BMW%20325i%20-%20325is%20Electrical%20Troubleshooting%20Manual.pdf - Page 110) that explains what wires go to what, but I have no idea how I'd interpret the data I'm getting. Is there a way to like, test these wires to find out what comes through them, and is there a way of interpreting that information? What kind of tool would I need? I'm assuming once I figure it out I can do something using an Arduino or Raspberry Pi 0.
Thanks!
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I was surprised a few days ago to find that the crank position sensor on a 1996 Honda Passport is the digitally processed output Hall effect switch.
We were putting the finishing touches on a 6VD1 to 6VE1 engine swap, to discover there was no spark. The trouble was found by removing the sensor from the block, poking a sewing needle through the insulation to attach the scope probe, then waving a magnet in front of the sensor with the ignition switch on. After reassembling, it started up on the second try. There are still a few codes to check, but it's running quite nicely.
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Put you car on a dynamometer and hook up an oscilloscope. Many engine sensor signals are analog. A low impedance probe or A-to-D input will alter the voltage that the engine controller receives, changing the engine's operating parameters. Also, some types of crank angle sensors output an increasing voltage as engine RPM rises, over 100 VAC on a high performance engine can be found there.
This page may be the starting point you're looking for: https://www.bimmerforums.com/forum/showthread.php?1430281-Bosch-Motronic-1-1-1-3-BMW
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Yeah, if it's an '89 car my instincts would say analog too, as I don't think that there would be any standardized digital interface. So yeah, I think probing the pins with an oscilloscope would be the best course of action.
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