O2 sensor lite on "82" 380SL
 

Help! My O2 sensor lite came on and I replaced the O2 sensor but the lite stays on. the dealer says it needs to be reset, I called Mercedes help line and the tech there told me to get another sensor because the O2 lite automaticaly resets itself. I exchanged the sensor and the lite stays on. I check voltage output and read .099 max and call Bosch. Tech at Bosch says the sensor is good and his book says to remove sensor lite bulb. I see this same cure on other websites so I call Mercedes again and talk to anothe tech. He tells me No that the lite resets itself and not to remove the bulb but continue trouble shooting the instrument cluster. I find ground on printed circuit in speedometer burned through and repaired but lites is still on. Where else can I check?

Thanks in advance
jwhook
380SL: S500