I have a 98 S90 with 70K miles. Recently when I started the car for around 5-10 minutes, the arrow light was on and the shift indicator was jumped between W and E. Somebodys told me that I need to replace the PNP switch, but others said that I just need to replace (flush) the transmission fluid? I checked the transmission fluid. It looks fine (I'm the first owner and have never changed or re-filled transmission fluid). My question is that is it possible to just replace the transmission fluid to resolve the problem? What kind of transmission fluid I have to use? Thanks.

 

Usually when the arrow light/shift indicator lights come on a fault code has been set and the box goes into 'limp' mode. You can get the fault codes read at Autozone or other similar outlets, usually free of charge.

If the PNP switch is the culprit you can try a temporary fix by moving the shift lever between P and L quickly between 15 and 20 times with the engine running and foot brake firmly applied.

As for fluid change on your car Volvo recommend changing it only in the following instances:
1. When the diagnostics unithasregistered fluid temp too high.
2. The fluid smells burnt and is discoloured but no fault code has been set.
3. On cars used as taxis or used forregular pulling of trailers or caravans for most of its mileage.

The fluid to be used is Dexron111 or Ford Mercon.