Attempted to get these fans to work again today, no joy. There are two relay "parts", one is the relay itself, which has a diagram, and the other is the "socket", that has wires already plumbed to it. So I attached the "socket" to the "relay", and went about wiring it up according to the diagram on the "socket". I thought it was odd that the white wire was ground and the black wire went to a switch, but off I went. Connected the blue wire up to battery positive with an inline fuse, and the yellow wire went down to fan positive. When I jumped the fan positive directly to the battery, the fans came on, which tells me there's also a good ground down at the fans. When I jump the switch directly to the battery, it lights up like it's supposed to, so I know the switch works.

So of course when I got everything wired and toggled the switch, the fans didn't come on. I tested the "socket" ground against the switch and battery positive, and the switch worked, so that ground is good. I tested "socket" power up at the battery by disconnecting the fused wire and jumping the switch there, and the switch worked, so I know the power connection is good. So it would appear that the power and ground wires off the "socket" are good, that leaves the switch and output wires. I already know the switch doesn't work when it's wired up to the switch wire, and without that working, I can't test the output wire, i.e. disconnect the output wire to the fan, flip the switch to "ON", then use a multimeter to see if there's voltage coming off the output wire.

Now what's interesting is the wiring diagrams on the relay and the socket are different. The output and power are the same, but ground and switch are reversed. I'm going to defer to the diagram on the relay as being the correct one, because that one says black is ground and white is for the switch, which makes more sense. I am SO frustrated by this whole ordeal I'm ready to go to the range and burn thru a couple of boxes of bullets. This is freaking ridiculous!

I'm at wits end now trying to get these fans to come on. What should be something fairly simple is turning out to be my worst nightmare. I mean, how hard can it be to wire these damn things up, when I know the fans work and the switch works when you jump them directly to the battery. It's got to be the freaking relay wiring that's making me crazy. So the next step I'm thinking of doing is unplugging the "socket", and wiring it up directly off the relay. There's only four terminals, so how badly could I screw that up?!

I was so frustrated I put everything away and went for a motorcycle ride, to help calm me down. This is so freaking ridiculous, I'm besides myself. Oh, and to further complicate things, I decided to jump the wires on the 14" Derale fan I took off, and guess what? Yup, I couldn't get that fan to come on at all, whereas the dual MBZ fans would come on with a direct jump. WTF, over?!

This is why automotive electrics make me so freaking mad. What should be something simple is going to take a rocket scientist to figure out...