Other than the ignition being on...that's the way I've bled brakes for 30 years. However on the H3, I eventually gave up on this method and used a vacuum pump.
Regardless of how you bleed the brakes, you must get all the air out of the lines. There is something very goofy and strange going on with the H3's brake system. As you hit 30 mph, the H3's computer initiates some sort of "purge" or "test" in the brake system. It will apply the RH side brakes for 5 seconds then release...then it will apply the LH side brakes for 5 seconds and release. When this happens, if there is any air in the system...the truck will dart hard for the ditch then hard for the centerline. Its very surprising and sudden, and sometimes the truck would slow itself down to 15 mph. All of this happens without any driver input to brake pedal. Also, there is no pulsing or ABS light whatsoever. You are merely driving along and when you hit 30 mph...it will dart right...then dart left. If you're not ready for it, you'll be off the road (or worse). I messed with mine for three months trying to figure out WTF?
The brake-thru (pun) came when I noticed that it only did this first thing in the morning. After I drove and applied the brakes several times...the problem went away. I deduced that this was because I had "pumped" the brakes several times and compressed the air bubble to the point where it wasn't a problem. Only after sitting overnight would the pressure bleed-off, and that's when the bubble would return to its hiding spot somewhere inside a brake line. The H3's computerized master cylinder was doing something to compensate for it. Once I got ALL the air out...it works great once again.
I vaguely recall a story years ago about a red solid-axle H3. The guy had installed Rockwells (overkill) and the truck had mysteriously activated the brakes at highway speed. He rolled the truck and totaled it. Obviously his center-of-gravity was way too high but, I can't help but think this roll-over might have been caused by improper brake bleeding.
