89 740GLE overdrive problem

[Mark G]

My 740GLE will shift into overdrive unexpectedly, as though I pressed the switch on the shift lever. The dashboard indicator light will light up.

Happens almost every time I use the car, and has already cost me a headgasket. Any advice?

[jlex]

My '88 704 was doing the same thing... OD light would come on unexpectedly while driving... it's the relay in the panel above the ash tray.... replace it & your problem will be solved.
jlex.

[Volvord]

It is also common for the wiring to wear through or break under the floor mats where they are constantly flexed from shifting, take a close look at the wires for damage.