im having a similar problem where my reserve light doesnt come at the gp postion.

i followed the fsm procedure and the gauge reades fine. bulb at instrument cluster is goood, harness is good. the 180 degrees makes sense if you think of a circle

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1986 300SDL, 211K,Dealership serviced its whole life
1991 190E 2.6(120k)
1983 300D(300k)
1977 300D(211k)