Need help on '90 200 instrument cluster lights

Brett Dikeman brett at
Sun Dec 22 15:14:25 EST 2002

At 11:01 AM -0800 12/22/02, Keith Lawyer wrote:
>My '90 200 has not been charging, and the alt warning
>light is not coming on with the key.  What concerns is
>me is that the light is inconsistent.  Sometimes it
>will come on, sometimes it will not.
>The exciter wire looks good

Was there 12v at the terminal?

>1) the alt bulb does not *look* burnt and contacts
>look good.  How can I test the bulb itself?

Multimeter.  Check for continuity.

>  If I
>guess wrong (pos/neg) I blow the bulb, no?

No.  Filaments don't have polarity.

>3) is it ok if I turn on the key with the IC removed

Possibly.  Don't recommend it.

>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.

Idle stabilization valve, is my guess.  On the CIS cars, they hum
quite loudly.  Should be easy enough to pinpoint.

"They that give up essential liberty to obtain temporary
safety deserve neither liberty nor safety." - Ben Franklin

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