Hi NorfyXR6,
The master cylinder will have nothing to do with this problem I dont believe.
When your mechanic says " not throwing any codes " is probably because the
ABS unit is faulty and will not communicate with the Scan tool device - ie will not detect or recognise the
ABS module.
Feel free to do that test first and see if it can detect an
ABS system.
If it cant see it -the module is faulty and should be replaced or repaired (better with lifetime warranty) as per the Ebay ad on my last post. only $150 !
Once my unit was repaired it worked perfectly immediatley and the lights cleared on start up and could be seen by the Scan tool when connected.
Good luck.