Round Relay Questions

[MoparBoy72]

What can you tell me about the round relays that are found in our cars? I am primarily looking for amperage ratings and wiring diagrams.

Is there any reason that I should not use these as headlight relays that will support 100 Watt bulbs?
Also, what is the difference between the red and black relays?






Any help is appreciated

Thanks,

[joetiii]

I just replaced one of the black relays for my fan blower, rear defrost and trunk lite in my 69.

Haynes manual has wiring schematics, but I don't think they show the values of the relays or the wiring hookup. Daniel Stern lighting has a schematic of how to rewire for modern high watt lighting. I did not use this black relay or stock wiring when I upgraded to H4s and driving lights. If you need to keep everything for concours, then run stock bulbs. Otherwise, I'd suggest using modern relays with larger wire.