Can anyone please suggest possible location(s) of the headlight relay (parts catalogs term it "driving light relay") in a 1990 full-size Blazer?

This relay accepts an oval-shaped female connector, and this relay has a flange on the top of it with a hole for a mounting screw. The Standard Motor Products part number is RY109T, and the relay has 5 male pins.

This Blazer has 5.7L small block 350 V8, Silverado package. (I believe it is more formally a V-1500 Suburban, though based on experience, suspect wiring system is similar/same as Blazer, and I know it as such.)

I have looked behind glove box, and in the area near fuse block (just above-left brake pedal), and do not detect this headlight relay (yet, at least).

Likewise, I have had no luck finding this headlight relay in the engine compartment yet.

I am hoping someone can please point me to a spot which I can then isolate for deep scrutiny, as means to compensate for my age-worsening eyesight (even with cheaters).

The issue I'm trying to address is headlight cut-out after about five minutes on high beam.

Low beams work fine all the time, provided I do not engage high beams during a trip.

As well, high beams return to operation if I leave the lights off for a bit before turning them on again.

Root cause thus appears to be electrical current-induced heating of some sort.

Unfortunately, various shop manuals (including Chevy's) and Internet resources equivocate as to whether this unit has this relay or not.

I am hopeful it does, and thus seek to find it as means to attempt "plug & play" problem resolution, as opposed to gutting steering column and replacing headlight switch as some references indicate may be required.

Thus, please also feel free to conjecture on whether my Blazer has this headlight relay.

Apologies if this topic has already been covered. I did not detect situation-specific answer in my copious search of historical threads.

Thanks!