92' 750's overdrive has been working just fine all the sudden the car does not start at the Economy "E" mode nor does it shift into the "E" ode. The vehicle starts in the "M" mode. When I try shifting into the "E" mode it shift but does not hold the overdrive mode. Additionaly the dash does not show "E" when I hold the overdrive switch. When I release the switch it goes back to the "M" mode.