I am having a problem in my 1994 940 automatic transmission sedan, , where the transmission will shift down to third gear and the 4th gear override light ( up arrow) will come on without warning. I am not touching the downshift button at the back of the gear shift. Sometimes if I slow down enough I can get it to shift back into 4th gear with the button on the gear shift but most times I have to shut down the engine and restart the car to get it to go away. As you can imagine, this is no fun when it happens on the highway. Any suggestions would be appreciated.

It could be a short circuit at the switch or the wire down at the reply is..I know what you are talking about becuase mine is the same model as yours. After the engine switch cut off , the orverdrive will be off automatically.

First I would replaced the overdrive relay it may be heating up and opening (short circuit in the coil) If that doesn't correct the concern the next step would be the solenoid on the trans. After that it trans time.

I am having a similar problem with my '92 Volvo 940, and I also suspect an overdrive relay problem. The vehicle does not shift into 4th gear and the RPMs approach 3500. Sometimes, clicking in the overdrive switch on and off makes it shift, but lately its been "stuck"-probably as a result of the relay since it is all electronic, especially since I hear a click in the dash when I press the button. Does anyone know the location of the overdrive relay in the '92 Volvo 940? Any site with a diagram and a manual?