Overdrive light

[der]

My 89 MKIII NA automatic will not shift in or out of over drive. The OD light does not come on. Fuel mileage is hurting!
Cannot get codes since light does not work. ????

Lowell

 

[Nick M]

Figure it out yet? The switch powers the light and sends a 12v signal to the trans computer telling the computer to use O/D.

Scratch that. I just looked at the EWD. The switch provides the ground for the bulb and the trans computer. But the switch is still only a signal. What was I thinking...