I just bought a 1995 940. It runs well, but the switch on the automatic transmission shifter does not work, so the car runs at 4000 rpm at 70mph. I know nothing about how the car should run. Does that switch enable a 4th gear ? What should I do to get this fixed ? thanks for your help.

 

If you press the button does an arrow come up on the dash?
The setup will always have overdrive active unless you press the switch and the arrow is on.

 

The arrow is ALWAYS on. Pressing the button does not turn the arrow off. And there is no overdrive as a result, I guess.

i am new to this forum. Thank you so much for your help.

Regards,
FPA

 

Then your overdrive mode is always on, henceyour 3rd gear is the max right now.
You should fix that or you will have to fill up your tank A Lot.

 

Maybe the relay is bad, or maybe the switch is broke?

Check here for everything you need: http://www.ipdusa.com/Volvo-940960/Transmission-&-Drive-Train/Automatic-Transmission/c-1-136-278-676/

If you will rarely push the button when it works, you can always get the OD bypass switch which makes it like a standerd 4 speed trans, but you will not be able to use the button anymore: http://www.ipdusa.com/Volvo-940960/Transmission-&-Drive-Train/Automatic-Transmission/Automatic-Over-Drive-Solenoid-Bypass-Kit/p-136-278-676-1031/

Click Here for relay locations.

 

Start by checking the relay.