pieni obc e34:seen

If the OBC doesn't come up the next step is to figure out why. The list of connections is given in the table below so start by checking that there is 12v at pins 6, 8, 9 & 17. The most likely culprit is pin 17 as there will be no power to this if your car doesn't have the auxiliary horn relay installed and without power at pin 17 the OBC will play completely dead. If there is no power at pin 17 an easy solution is to cut the red-grey-yellow wire that goes to pin 17, cut it as far from the connector as possible to make life easier, and join this to the red-yellow (red with a yellow stripe, there's also a yellow wire with a red stripe!) wire that provides power to pin 9. You could join these via a 5 or 10 amp fuse if you prefer and it may be no harm to tape off the end of the red-grey-yellow wire coming from the car so it can't cause any problems.

Digital clock/temperature indicator
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pin4: ground
pin5: blue/red/yellow, temp sensor
pin8: from fuse F1
pin9: from fuse F20
pin18: white/blue, chimes
pin19: white/red, chimes
pin22: grey/red, light switch

lisää tuolta http://www.bmwe34.net/e34main/upgrade/OBC.htm