SOUND HORN OK PLEASE

MIND BOGGLING

Vehicles with this type of signage first arrived in Goa after the Indian Govt. takeover in 1961. At present the only thing that is 'OK' seems to be the honking, but not the roads, the drivers or their driving habits.  Honking apparently goes on and on, sometimes without rhyme or reason, and even when there is no one around (force of habit, I guess). 

I've tried to figure out the above signage mainly on trucks, ever since the time I learned to read, but never really understood it. HORN PLEASE OK, PLEASE SOUND HORN OK, PLEASE OK HORN, BLOW OK HORN, etc. I don't really know whether the horn of the guy in front of you is okay or whether he requires that you get your horn repaired if that's ok with you. Will someone please enlighten? 

I"M OK, YOU'RE OK, HORN OK, BUT TRUCK BRAKES NOT OK, TRUCK DRIVER NOT OK (may be drunk) SOUND OF HORN IS NOT OK, TRYING TO FIGURE OUT WHAT IS OK. I ASKED A DRIVER BUT HE DIDN'T SEEM TO KNOW WHO IS OK? 

SO IF YOUR HORN IS OK KEEP BLOWING IT ALL THE TIME OK? 

PLEASE