Please help!

After driving on the highway for some timeabove 55mph(80km/h)theup-arrow on my dashboard will suddenly begin to flash;at the same time,the drive mode selector lights on the geargoes berserk. The gear shifts fine without any problem. I got the car scanned at a local workshop and it came with error code PO740. Since then I have had the tranny changed, swapped ECM&TCM from a similar 960 thatdidn't have a tranny problemand had the wiring from the tranny to the 2 controlled modules checked. The problem still persisted withthe PO740 code.The only other problem have had with the car so faris that the engine sometimes overheat while the temprature indicator arrow stays in middle position.

Any suggestions on what the problem could be?

 

If you have changed almost everything I would have to say it would be wiring somewhere.

 

Thanks tech i'll recheck the wiring.

One thing I need to add though is that the mechanic and I again tested the car in sport mode and the light did not come-up. It seems to come on only when I drive in the economy mode.

I'm begining to suspect the drive mode selector switch. Do you think this could be the problem?

 

It is possible.