He was suggesting you splice into the wiring for the high beams,at the bulbs.I thought instead of running wire from the bulb socket,run it from the high beam wiring direct from the signal switch.You know for a fact that the high beam headlights are getting power,both on high and on flash to pass.So the actual fault lies between the switch and the HB indicator in the gauge cluster.
I would run a couple more tests just for the heck of it before you start running wires all over.You have a volt/ohm meter...right? Ok,now disconnect the two wire harness plugs on the back of the gauge cluster.Disconnect the HB socket from the board.Now turn your meter on resistance (ohmmeter setting,looks like an upside down horseshoe).Now,looking at the reverse side of the board with the HB socket on the top,put one probe on the contact that the bulb socket would normally connect to.Probe the lower contact that traces down and to the right which ends where the harness would plug in.Now put the other probe where the trace ends at the harness.Make sure the probe touches the exposed copper trace on the plastic strip.The meter should read 0 ohms when both probes are in the correct spot.If it shows "out of range" or some sort of infinity symbol or even nothing at all then move the brobes around to make sure your getting a good connection.The meter should not read higher than 0.1 ohm.If it does then you have a connection problem.Clean the contact area on the board with isopropal alcohol (clear rubbing alcohol 70 - 90% ).The other trace on the top of the bulb socket is ground.You'll notice that many other traces connect with that one.
The other and last test you can try.
Where the harness plugs into the gauge cluster,probe the pin (On the harness plug) that connects to the HB.You can do this two ways.You can set the meter to (DC volts ) setting.This setting may show 2 lines,one that is dashed or broken,aand the other a solid line (thats DC Volts).Make sure you set it to a range that reads up to 14 V.Now,with the one probe on the plug,turn your headlights on and switch to high beams.Connect the other probe to a good grounding source such as bare steel with a ground tied to it.The meter should read 11 - 14 volts with the HB turned on.If it doesn't then theere is a fault in the wiring going to that plug.The other method I mentioned was to use either ohmmeter or continuity and probe from that plug ..and connect the other probe to the correct pin on the plug that is connected to the signal switch.Doing it this way just checks for a break in the wiring between the switch and cluster.You leave the headlamps off (no power).Use the continuity setting for this.That way it will give you an audible beeeeep whenever the connection between the two probes is complete.When ever you remove the probes or there is a bad connection somewhere,you wont hear the beep.This helps you trace broken wiring easily without having to constantly look at the meter.