TECH TIP FOR JUNE, 1994

WE HAVE BEEN SENDING OUT TECH TIPS FOR MORE THAN 2 YEARS NOW, BUT SOME RECENT DISCUSSIONS INDICATE THAT A REVIEW OF CERTAIN FACTS IS IN ORDER:
1)NEVER, NEVER, EVER, UNDER ANY CIRCUMSTANCE,ARE YOU TO REMOVE A CABLE FROM THE BATTERY WHEN THE ENGINE IS RUNNING. THE SPIKE CREATED CAN RUN WELL OVER 200 VOLTS AND IF IT DOESN'T FRY EVERY COMPUTER CIRCUIT, IT DAMAGES THE ALTERNATOR. THE ORIGINAL THEORY BEHIND WHAT IS CALLED "LOAD DUMPING" IS THAT IF THERE ARE ANY QUESTIONABLE PIECES, YOU WILL FIND THEM RIGHT NOW.  WHAT REALLY HAPPENS IS; THAT IF THERE WERE GOOD PIECES, YOU JUST MADE THEM QUESTIONABLE!!

2) YOU CANNOT RUN ANY MEANINGFUL TESTS ON THE STARTING, CHARGING, OR WIRING SYSTEM IN AN AUTOMOBILE IF THERE IS NOT A FULLY CHARGED BATTERY IN THE SYSTEM. WE HAD A CASE THIS MONTH WHERE A SHOP (WHICH WILL REMAIN UNNAMED, TO PROTECT THE INNOCENT), WAS GOING TO REPLACE BOTH THE BATTERY AND THE ALTERNATOR, IN SPITE TELLING ME THAT THE BATTERY WOULDN'T TAKE A CHARGE, EVEN AFTER BEING ON THE CHARGER FOR MORE THAN 1/2 HR. THE CAR ARRIVED AT MY SHOP, WHERE I REPLACED THE BATTERY, FOUND THE ALTERNATOR TO BE WORKING PERFECTLY, AND SENT THE CUSTOMER ON THEIR WAY.

3) MOST WIRE USED IN AUTOMOTIVE APPLICATIONS IS OF THE MULTI STRANDED VARIETY. THIS TYPE OF WIRE, EVEN IF ONLY 1 STRAND IS STILL CONNECTED, WILL LIGHT YOUR TEST LIGHT TO NEAR FULL BRILLIANCE. THIS DOES NOT MEAN THAT THE WIRE WILL SERVE ANY OTHER USEFUL FUNCTION, BECAUSE IT IS NOT CAPABLE OF PASSING SUFFICIENT CURRENT (READ APMS) TO DO ANY WORK. FOR THOSE OF YOU WHO DO YOUR ELECTRICAL DIAGNOSIS WITH ONLY A TEST LIGHT, YOU HAD BETTER INVEST IN SOME REAL EQUIPMENT, OR LEAVE THE ELECTRICAL WORK TO THOSE WHO HAVE.

4)VOLTAGE DROP TESTS ARE PERFORMED WITH CURRENT FLOWING IN THE SYSTEM.IF THERE IS NO CURRENT FLOWING, YOU PROBABLY WILL NOT HAVE A MEANINGFUL DROP. IF YOU HAVE A MEANINGFUL, READABLE VOLTAGE DROP ON A STATIC TEST, YOU, MY FRIEND, ARE IN DEEP DOGGY DODO!

AND NOW THE ANSWER TO LAST MONTH'S QUIZ:
THE MECHANIC FOUND THAT THE FACTORY HAD CONNECTED THE MAIN VEHICLE GROUND CABLE TO THE AIR PUMP PIVOT BOLT. THE VOLTAGE DROP THROUGH THE MULTIPLE CONNECTIONS ON THE GROUND SIDE OF THE SYSTEM WAS GETTING EVER WORSE, UNTIL FINALLY IT COULD SUPPORT SOME OF THE ELECTRICAL SYSTEM, DEPENDING ON THE LOAD, BUT NOT THE STARTER'S DRAW. THE CURE WAS TO CLEAN A SPOT ON THE BLOCK AND MOVE THE GROUND CABLE TO IT. AFTER DOING THIS, OF THE TRUCK'S ELECTRICAL PROBLEMS WENT AWAY AND TO DATE, THERE HAS BEEN NO REOCCURRENCE.