corradomaster

OK my 4 matic light was on all the time, I have unpluged the battery and the light went off and stays off while driving but when I come to aa complete stop and take off the light gives me 2 longer flashes about 2 seconds apart. Before I have seen the system giving me short flashes also before the battery unpluging. The 4matic system is in the function mode.
So whats the right way to check for codes ? If there's a trouble does it tell you each time you take off from a stop ? This is my fourth w124 wagon 4matic and I never had problems before. Today the road was wet and I could make rear wheels spin and no light comes on. Winter is coming and I'm about to burn this car and buy a Subaru or Audi AWD.
Please help
Thank you in advance.