89ragtop

I wired up my foglights. I used a 30 amp relay. There are 4 terminals on the relay.

power source - to battery
switch - to switch
relay ground - ground
lights - power to lights

I heard the relay click once when I flipped the switch, but I forgot to connect the ground to the lights and the ground for the switch. Now, with everything hooked up, I get nothing.

I did not put an inline fuse between the power source and the relay. Did I blow the relay?

Stuart Moss

I don't understand your relay connections, or why you want/need to ground the switch.

A four terminal relay should be connected as follows (following your post):

Think of the relay in two sections, the "contact" section which acts as a toggle switch, and the "coil", which activates the contacts. The contacts will handle a large amount of current, the coil needs only a fraction of an ampere to operate, needing only 18-20 gauge wire.

Two of the relay terminals will be the "switch", which looks like you connected properly. One side to the battery, with a fuse at the battery side, and the other terminal to the fog lights, which will have +12 present when the switch is turned on to energize the coil.

The other two terminals will be the relay coil. Once side you said you connected to ground. Fine. The other side must receive +12 (battery positive) through your switch. This is why I didn't understand why you indicated the switch would be connected to ground. The switch must be connected to +12 (probably +12 when the ignition is on so the lights cannot be on with the car off).

Of couse, without the lights connected to ground to complete the path, they will never come on.

Does the relay still "click"? Again, I don't understand if the relay coil was connected to ground on both sides. If so, it would never operate, or "click".

I doubt you damaged anything. If so, it'd probably be the switch if you connected one side to ground and the other side to +12, at which time you would be shorting positive to ground through the switch. If the contacts held up, the wires would start to burn. Perhaps your switch acted as a "fuse" and sacrificed its life if it was connected this way.

Let us know what happens. And you may want to put a fuse in the positive line at the battery side before doing anything else...

89ragtop

Durrrrrr.

Brain fart.

Switch needs power, not ground. WTF was I thinking?

Don't worry, I kicked my own a$$ for that.

I don't think I damaged anything. I knew it was something simple and stupid that I had done. I'm sure when I hook the switch to power it'll work fine. Everything is wired correctly other than that.

Thanks.