I have a 1985 Toyota 4runner SR5 5 speed and have the same problem, I bought a new pin for the horn assembly from the Dealer, found I did not have the time to take everything apart, I took a 22LR round, pulled off the bullet, dumping the gun powder and then inserting the "empty round" into the 22 rifle and fired the primer, on the grinder I filed the shell down a third and put some dielectric grease inside, inserted it over the original pin that is worn out, re-assembled the wheel back, and horn works!!
I have a 1985 Toyota 4runner SR5 5 speed and have the same problem, I bought a new pin for the horn assembly from the Dealer, found I did not have the time to take everything apart, I took a 22LR round, pulled off the bullet, dumping the gun powder and then inserting the "empty round" into the 22 rifle and fired the primer, on the grinder I filed the shell down a third and put some dielectric grease inside, inserted it over the original pin that is worn out, re-assembled the wheel back, and horn works!!
Is dielectric grease used on the contact surfaces? Not sure if it would help or just collect dust.
Where did you find the pin??
I bought one on Ebay.
Amazon