Replacing the OPEN Relay

In Superior Lift Gates controllers built before July 2004 a relay inserted in the OPEN line.  The purpose of this relay is to isolate the OPEN pin of the microcontroller from voltages that may be induced into the wires connected to it by lightning or static discharges.  In some cases the lightning discharge is powerful enough to damage the relay. 

Notice that the relay was inserted in the white wire that originally ran from the OPEN terminal to the microcontroller by cutting the white wire and inserting the relay.  The relay can be removed from the circuit by disconnecting the white wires from the relay and connecting them back together.

The relay can be replaced with most any 12-V DC relay by duplicating the wiring shown above.  The diode is internally connected in the Hamlin relay but most relays do not have the diode.  The diode can be connected externally.  A 1N4001 diode will work.

Suitable replacement relays and diodes from Radio Shack are:

Part                                    Part number

Reed Relay                          275-233

12 V DC Relay                    275-241

1N4001 Silicon Diode          276-1101