I've diagnosed the left relay under my hood is ticking Very Loudly... Never heard this before, I thought it was my dash rattling like mad until I popped my hood and discovered it was one of my 2 relays on the firewall.

There are 2 relays on the driver side of the firewall where the brake booster is.. It's the LEFT one..

What relay is this? Why would it be ticking really loud?? On it's way out?

Thanks