After driving on the highway for some time above 55mph(80km/h) the up- arrow on my dashboard will suddenly begin to flash while at the same time, the winter/sports/economy lights on the drive mode selector switch begin to oscillate. 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 that didn't have a tranny problem but the problem still persisted with the PO740 code. Any suggestions on what the problem could be? A point to note however is that the problem does not occur while driving at low speed.
