Had the flashing arrow and 313 code come up meaning the transmission PNP switch was bad. Referenced Volvospeed Bay 13 for an excellent description on how to replace the $150 part. Along the way, he mentions an alignment tool to set the PNP in the right place. I did not have the tool so I improvised by using vise-grips to hold two straight 2inch jigsaw blades on either side of the flat part of the shaft. Then, center the marked line between the blades and the PNP switch is lined up. This worked as I got everything put back together, cleared the codes and so far, no more errors. The whole thing took me 3 hours and I'm not an experienced greasehead.