How does the diode from emitter to collector in a TIP120 dissipate current generated by the coil of a relay?
http://www.st.com/content/ccc/resource/technical/document/datasheet/f9/ed/f5/44/26/b9/43/a4/CD00000911.pdf/files/CD00000911.pdf/jcr:content/translations/en.CD00000911.pdf
I would suggest it does not. It only blocks current flow the same as the turned off transistors, and allows high voltage to be created from the coil generated current.