Q: Does this work with the HONEYWELL sending unit that comes on the Rotax 912? The back sure looks different. What are all the pin positions for when the transmitter has only 3 pins? comment to Acft Sp: pictures of the back side connectors would sure help us reduce return shipping costs. Thanks This is the correct tach for your application. The white wire from the sender will go into pin 5 of the DB 9 connector. The red wire will go to pin 2 and the black wire will go into pin 8. You will then need a jumper from pin 2 to pin 1 which will be connected to power. Also a jumper from pin 8 to pin 9 which will then go to ground.