1990 740 Turbo - 209k miles, Auto...

1990_740Turbo · Post by **1990_740Turbo** » 12 Dec 2007, 05:55

My Turbo that I have owned for about a year now has never been able to go into 4th gear. I purchased an Overdrive Relay 2 months ago when I finally had to start taking it long distances, but that didn't work. So I can't figure out how to get it to shift from 3rd... I can't go more then about 45-50 MPH without destroying my gas milage.

Any ideas?

Post by **billofdurham** » 12 Dec 2007, 12:21

Usually when the overdrive fails to engage, barring major mechanical problems, the fault lies in the switch, wiring or solenoid.

I have found that the solenoid is usually the culprit. Test as follows:

This is Fig.3:

Bill.