Need help on '90 200 instrument cluster lights

Huw Powell human747 at
Sun Dec 22 23:46:48 EST 2002

> Huw, you say the oil pressure control unit could be buzzing?
> What op control unit?  Clearly I'm missing something
> here, I'm only aware the op sender(s) and oil pump.

if the 200 is anything like the cars I know better, and I bet it is,
there are two oil pressure senders, which signal the control unit.  it
also gets a tach feed, and buzzes, etc., based on rpm and the two
senders.  (ie, low rpm, low unit, higher rpm, higher sender comes into

since it gets a tach signal, I *suspect* it is what controls what goes
to the alt signal wire, but maybe not.

the alt signal wire defintely makes a visit there on its way to the alt,
but this might also be related to the testing of the idiot lights upon
"key on".

if that helps at all...

oh yes, the OPCU is a tall relay like thing in the aux relay panel
usually, there would be part numbers on the relay file at my web site
with any luck.

Huw Powell (I think)

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