Need help on '90 200 instrument cluster lights
human747 at attbi.com
Sun Dec 22 22:33:19 EST 2002
my feeble additions to Brett's comments...
> 1) the alt bulb does not *look* burnt and contacts
> look good. How can I test the bulb itself? If I
> guess wrong (pos/neg) I blow the bulb, no?
as he said, no. You cna use a meter, a 12v/ground power supply, or find
somewhere else it fits and plug it in.
> 2) can anyone tell me what wire should power the bulb
> when I first turn the key? I wanna make sure it's
> being TOLD to light. From my wiring diagrams I'm
> thinking gray/yellow?? Or would it be one of the
> multiple blue wires back there? Can anyone even point
> me to the right *connector?*
It's complicated, and I believe no one truly understands it, even Hans &
Franz. But basically the circuit is through that blue exciter wire to
the alternator, via the oil pressure control unit.
> 3) is it ok if I turn on the key with the IC removed
I ran my 82 coupe without a cluster, no problem except for the no
speedo/no tach confusion.
I think as the years go by and the cars get more complicated (ie, code
reporting and electronic instruments versus analog) this would be less
and less advisable, ie I agree with Brett.
> 4)finally, this might mean something to someone: when
> the bulb was not lighting I also got a weird hum from
> the dash/firewall area when I turned the key. I'm
> thinking this might be the ABS control unit based upon
> the wiring diagrams. Does this mean anything to
Do you have a low voltage battery condition? If so, maybe the oil
pressure unit is struggling to do its job and buzzing. I'm not so
familiar with the 200 layout, but I suspect this unit is near the ABS
one, so they might be easily confused as noise sources.
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