I have owned a 2001 S80 since last August! Recently when I go into a turn there is a terrible pounding noise in the front end that sounds like metal being hit with a hammer! The little yellow triangle comes on on the dash! Does not seem to so it when the car is going straight! I have recently had 2 messages come on intermittently! DSTC needs work and ABS needs work! But they both go off. If I turn off the DSTC none of this occurs! What is this! I had my mechanic check the rack and pinion and anything else in the front end but there was no problem seen! Help!

 

What does the manual say about the DSTC?