Originally Posted by mmckenna
Not sure if it applies to the CDM's, but I know on some of the Motorola radios there was a modification that would let them scan without a mic connected. I think you installed a jumper, or maybe it was remove a resistor, in the head to make it do that. Probably would be a good idea to disassemble the head and take a good close look at it to see if anything is out of place.
Not necessary on the CDM's. The older Radius, MaxTrac's, GM300's, etc. needed a jumper between Pins 3 & 4 of the mic connector to scan or hold PL without a mic. That was best accomplished with a jumper in an RJ45 plug rather than opening up the radio. The CDM's need neither as it is all in the software.
I'm not familiar with any jumper or other component on the heads that needs to changed.
However. making sure the flat ribbon between the radio and the head is properly seated is a good thing to check.