Mega i2c pins not working

[adamr1]

I am working on a project that includes the v2 motor shield, i2c fram unit, and a 8x8 matrix with i2c backpack. I had my project working great on an uno but I started to run out of memory and moved my project to a mega. I switched the i2c pins from A4&5 from the uno to 20 and 21 on the mega. I can't get any of the i2c components to work. I've tested motor shield, fram, and matrix seperatley and I cannot get them to function. For instance, when I run the fram example and enter the serial view, it just hangs but if I remove the i2c wires (on 20 and 21) the example continues and I get the cannot be found error. I've replaced wires, done everything I can think of. Again, it worked fine on the uno.

[Franklin97355]

How are you connecting to 20 and 21 and did you remove the connections to A4 and A5?

[pburgess]

Can you test the components individually, with only one I2C device physically attached at a time? e.g. try just the matrix running one of the stock examples.

Also, tried swapping the wires to 20 & 21?

[adamr1]

I have not tested seperatley but will try that. I did try swapping 20&21 with no luck and replaced the wires with no luck? Can the i2c bus go bad on its own? I've loaded different sketches and the board works otherwise.