Anyone know which wire powers the gauges on the opposite side of the firewall?

[bennylava]

All my gauges died after I got a little too happy with the power washer. I always try to be careful, but apparently the 87 truck didn't think I was careful enough. So I removed the cluster, and have confirmed it's got a good ground.

But when I checked the power wire with the multimeter, it's only showing millivolts, not volts. So that must be the problem, no power.

But I have no idea which wire that would be, on the other side of the firewall. I'm assuming it goes out through that big square bulkhead plug.

Any help would be greatly appreciated, thank you!