MikeShields

1991 300SL. About 50% of the time while driving the Rollbar warning lamp comes on and the rollbar switch lights flash.

Suggestions appreciated on checks, fixes or parts to replace.

sushipaste

Battery if its old. Otherwise, you will need a STAR diagnostic scan

MikeShields

Thanks, I will check electrical. For the 1991 I have an LED I can hookup to the plugs in the engine top left -- but by STAR diagnostic do you mean something more that I'd have to take into a dealership?

Kebowers47

there are numerous electrical systems involved in the top systems and each of them can be faulty. A good computer diagnosis will likely point to the faulty switch,connector, position sensor. There are position sensors everywhere and one of them is out of adjustment or you have a (mostly) broken wire.

RScott

Read/Erase and then read again the codes from "plug" #7. You can use your LED to count flashes, or you can look at the roll bar fault indicator. When you have the codes you look of their meaning in the diagnostic manual.