NHTSA Complaint #10143087 — 1997 CHEVROLET BLAZER

I HAVE A 97 BLAZER 4X4 WITH A LITTLE OVER 113K MILES. I'VE BEEN HAVING PROBLEMS WITH THE VOLTAGE (I THINK) FOR A WHILE NOW. THE VOLTAGE METER SWINGS FROM JUST ABOVE 9V TO OVER 14V WHEN I STOP AT A TRAFFIC LIGHT. I'M CONVINCED THE GAUGE IS NOT TO BLAME BECAUSE WHEN I PUT A LOAD ON IT, IT INDICATES 9V TO 10.5V, THE DASH LIGHTS DIM, THE HEADLIGHTS WIL ALSO DIM. I'VE ALREADY REPLACED (3) ALTENATORS AND THE BATTERY TWICE WHICH IN 4 MONTHS AND EVERYTHING IS STILL THE SAME. THE GAUGE WILL READ JUST ABOVE 14V WHEN I'M AM DRIVING THE TRUCK WITH NO PROBLEM BUT THE MINUTE I STOP AT A TRAFFIC LIGHT THE VOLTAGE GAUGE DROPS DOWN TO 9V OR 10.5V DEPENDING ON WHAT ACCESSORIES AM RUNNNING ON MY TRUCK. TEMPERATURE AND FREQUENCY BETWEEN TRIPS SEEMS TO NOT MAKE A DIFFERENCE EITHER. THE ONLY THING I HAVE DONE TO THE TRUCK EVEN REMOTELY CONNECTED TO THE ELECTRICAL SYSTEM IS TO SWAP THE RADIO, BUT I USED A WIRE HARNESS TO CONNECT THE WIRING. I'VE CHECKED AND WILL RECHECK TONIGHT FOR LOOSE WIRES OR BAD GROUNDS, BUT OTHER THAN THAT I'M LOST. ANY HELP? *NM