D5 error for coin slide. Cleaned off sensor still had D5 error. Ohmed out wire harness good, corrosion on user interface board. Cleaned it up using electrical spray. Still had D5 error code. Swapped in user interface and solved the problem. Tech sheet says what steps to take but did not provide how to test the coin sensor other than shorting 2-3 connections on Ui will simulate good coin sensor.