diode in relay harness?

[Blazer406]

Looking at buying a few 30A relays on fleabay with the plastic harness they plug into.... some have a diode shorted in between two terminals.... some don't.... what does the diode do for you? keep you from hooking it up backwards?

 

[TURBOV6]

Those relays you are buying is usually used from starter kill for alarm systems.

The diode is used so there is no negative feedback going back to the alarm system or to the ignition.

The diodes are between terminas 85/86 of the coil of the relay, just cut the diode off at the hardness.