Programming Failure Work Around
So you’ve attempted a programming on an MS42 or MS43 DME and it failed. Now you have no communication to the DME. Are you boned???
Give this procedure a shot...
Access the DME relay and verify the loss of ground
Apply a good ground to pin 4 of relay and verify B+ out of pin 2 at relay.
Attach battery charger, and with a volt meter, maintain approximately 13.5v. Lower than 13 or higher than 14 will cause the programming to abort.
It may take over 1 hour to fully complete the programming. If fails again, perform a battery disconnect overnight and try again. If it fails again, you can attempt to bench program the DME.
Hook up the DME as shown.