Stock:
Each headlight harness (9003) has 3 wires: hot wire that goes hot for both hi/lo, a ground wire that switches for lo beam, a ground wire that switches for hi beam. When no lights are on, each wire in the 9003 floats (neither hot or grounded).
Now modified:
Each 9003 harness now drives a bosch style automotive relay.
On both sides of truck, the hot wire from the 9003 harness now goes to 85 on a relay which is the hot side of the trigger solenoid to turn on bulb. The ground side of the trigger solenoid goes to a constant ground, so the lo beam grounding switch wire from 9003 harness is now empty.
On both sides of truck, the hot wire from the 9003 harness
also drives the hot side of another solenoid that triggers the high beam shutter. The ground side of that solenoid goes to the high beam grounding switch in the 9003 harness.
Situation:
This setup is great. It works perfect because with this setup, there is no power interruption to the HID ballast just to trigger the hi beam shutter. If I wired the lo beam solenoid ground to the 9003 harness, there would be an interrepution to the ballast. The interruption is why people need to install a capacitor to carry that brief power during the hi/lo switch on a retrofit.
I would have just bought a harness like
the Morimoto one, except I really don't like it because it only pulls from one side of a dual circuit to go through one fuse and one relay to then split again and drive both left and right.
That's super dangerous. Any failure point through that harness will knock out both lights at once. No thank you.
I made my harness with redundant circuits for both sides and they have independent fuses and relays. It works great, but the dang blue light on my dash does not work anymore. Not that I really need it... I sure know when high beams are on lol.
When switched for lo beams, there is very little solenoid current through the hot 9003 that grounds common (so there is no current returning back through the lo switched ground in 9003).
When switched for high beams, there is very little solenoid current through the hot 9003 that grounds back through the hi switched ground. And there is still a little more hot current that's still driving the lo beam solenoid.
So I can't imagine why the hi beam indicator stopped working?