Important meaningless info! I have discovered a disturbing GM Factory Fuse Panel Wiring Mistake. (FFPWM). This mistake has never been noticed in over 60 years. I reveal this copy written, intellectual secret here on Stovebolt.com. I can be contacted by PM/Email for interviews, by Nobel prize committees, magazines, job offers, letters of congratulations and so on. It is with great humility and modesty that I amazingly have become a idolized mentor guru who will serve my unknowing public.
Part 1: The operation:
Since GM started offering factory turn signals and in-cab fuse panels in about 1960. There was a two prong flasher receptacle. The flashers are of the "thermal" 552 type. We have always known that on those flashers that "X" prong is for ignition switched battery power. We also know that "L" is for "Load". The thermal flasher has two circuits inside, one small, high resitance wire coiled around a bimetal strip. The other circuit is the primary circuit, basically the strip inself flexing, touching a contact which passes full voltage to bulbs. These flashers could be called a normally open momentary switch or a relay, kind of. When the turn signal switch lever is moved, the switch connects voltage to either left or right bulbs. Voltage comes in the "X" flasher terminal thru the small coil circuit, out the "L" and into the turn signal switch. Voltage/current gets distributed by the turn signal switch to the proper bulbs, thru bulb and into ground. The low amperage coil-wrapped strip inside flasher gets hot, without lighting bulbs, and flexes to touch the primary contact. Then voltage takes the "big" primary path to light bulbs. Strip current goes to zero and strip cools. Strip flexes away from primary contact, gets some current and back and forth every ~ second.
Part 2: The "mistake":
At the rear (or inside) of a GM fuse panel, are the factory harness wires in and out of the panel. On the Chevy and GMC wiring diagrams that I have studied, 1960 to around 1973, they used a brown or red wire from battery switched power to a flasher socket and a purple/Vio wire, for the load, to the other socket The purple goes to the turn signal switch. There is only one way to install a two prong thermal flasher into the sockets. GM has the RED or BRN power wire wired to the "L" prong socket and the Purple or VIO load wire wired to the "X" socket!!!!! Holy Cow, how come nobody noticed? "How can millions of flashers work if it's so "wrong" Bartamos? or whatever your name is?"....because the heater circuit can be wired either way and heats the strip.... Then when primary contact is "thrown", full voltage goes toward the grounded bulb.... and
The flasher never knows the difference. If GM ever noticed the error, seems they would have changed the diagram at some time.
I post this for those who are installing an aftermarket T/S switch with hang down flasher, for someone rewiring their factory fuse panel or buying a fuse panel for DIY harness build. It may help to avoid confusion if following a factory wiring diagram or copying and old fuse panel. No worry about harness kits, they have it "correct". With aftermarket column turn signal switches, follow direstions.
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