P1317 rough road, the defender uses a striped down abs ecu as a rev limiter. there is more to that but it is the basic function.
though the 96 and up defender did not have abs, the gems ecu needed to see wheel signal thus, it uses all 4 wheel sensors, a signal to engine ecu and power connections. no abs failure light.
check your wheels sensors to be fully seated by using a short drift made out of a wooden broom handle and tapping it with hammer, sometimes you feel the sensor bottom out other times you can see it move.
check your sensors for proper operation, check all connections including main connection to abs ecu located under passenger seat. if all is well you should be able to clear codes by using an abs capable scanner or a land rover dedicated scanner, choose to diagnose discovery 1 abs as scanners do not recognize defender abs.
much of this info is in the rave.