Joel, I'm not sure what you're trying to accomplish by clearing codes. In most cases there's a fault that has to be remedied so the light stays off. Some faults do not keep the light on. The light will come on to let you know something wrong then the light will go off. Fault codes are stored in system memory so a technician knows it occured since the last time codes were cleared. Just because the light is off doesn't mean there are no faults the system is dealing with.
83 300SD ... $950, see cars forum