its the hdm solid state module. Looks like a small relay in your under hood fuse block. Drl is like 70% power. Headlights are 100%. The lower voltage reeks havoc on ballasts.. and relay harnesses.

I know on the trailblazer they use a capacitor on the signal to run it at 100% all the time.

I haven't personally done this on my 04 never had any issues....but I just found out recently this only effect 06+

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