TECH TIP FOR AUGUST, 1994

IN THE "TECH TIP" FOR JULY, 1994, WE REPORTED ON BATTERY GASS INGCAUSING DAMAGE TO WIRING AND "NO STARTS" IN 92-93 FORD EXPLORER'S. DAVE NICHOLAS OF DAVE'S AUTO SERVICE, REPORTS THE SAME PROBLEM IN A 1990 EXPLORER (4.1L), AS DOES A REBUILDER IN THE WOODSTOCK AREA. IT APPEARS THAT EXPLORERS FROM 1990 ON ARE SUSCEPTIBLE AND SHOULD BE CAREFULLY INSPECTED DURING REGULAR SERVICE TO AVOID A BREAKDOWN. OUR ORIGINAL CONCEPT BEHIND THE "TECH TIPS", WAS TO SHAREINFORMATION MADE AVAILABLE TO US, WITH THE PEOPLE IN THE LOCAL INDUSTRY. WITH THIS IN MIND, IF YOU COME ACROSS A PROBLEM WHICH IS UNIQUE, AND CAUSES YOU HEADACHES BEFORE YOU CAN DIAGNOSE IT OR FIX IT, PLEASE CALL US AND TELL US ABOUT IT. WE WILL PUT IT IN THE NEXT TECH TIP, AND OUR INDUSTRY WILL BE BETTER OF FOR YOUR HAVING SHARED THE INFORMATION.

A FRIEND OF MINE, AT OAKVILLE STARTER ALTERNATOR, HAS TAKEN THE TIME TO PREPARE THE FOLLOWING DESCRIPTION OF THE WIRING USED ON THE FORD IAR ALTERNATOR. THIS IS THE ALTERNATOR WITH THE BLACK REGULATOR HELD ON THE OUTSIDE OF THE BACK BY 4 TORX SCREWS, AND WAS FORD'S FIRST ATTEMPT AT AN INTERNALLY REGULATED ALTERNATOR. THE UNIT HAS TWO PLUG©INS, EACH HAVING THREE WIRES. ONE PLUG HAS TWO LARGE WIRES AND ONE SMALL WIRE. THIS IS THE MAIN BATTERY PLUG. IN THIS PLUG, THE TWO LARGER WIRES ARE LIVE WITH FULL BATTERY VOLTAGE AT ALL TIMES, WHILE THE SMALLER WIREDISAPPEARS INTO THE WIRING LOOM AND EVENTUALLY RETURNS TO JOIN UP WITH THE CENTRE (S) WIRE IN THE SMALLER PLUG. IF THIS WIRE IS UNPLUGGED, THE ALTERNATOR WILL CONTINUE TO CHARGE BUT THE LIGHT WILL NOT GO OUT. THERE WILL NOT BE ANY POWER ON THIS WIRE WITH THE ENGINE OFF. IN THE SMALL PLUG, THE WIRE TO THE (I) TERMINAL IS USED TO TURN THE REGULATOR ON, AND SHOULD BE LIVE ONLY WHEN THE KEY IS IN THE "ON" POSITION. ONCE THE ENGINE HAS STARTED AND THE ALTERNATOR BEGINS TO CHARGE, DISCONNECTING THIS WIRE SHOULD HAVE NO EFFECT, UNLESS THE ENGINE IS STOPPED AND THEN THE REGULATOR WILL HAVE TO BE EXCITED AGAIN.

THE THIRD WIRE IN THE SMALL PLUG, THE (A) TERMINAL, IS ACTUALLY THE SENSE TERMINAL (HOW THE REGULATOR TELLS WHAT THE CONDITION OF THE BATTERY IS), AND SHOULD ALWAYS BE LIVE. IF COMPLETELY DISCONNECTED, THE ALTERNATOR WILL SHUT DOWN; HOWEVER, SINCE IT IS A "SENSE" WIRE, ANY INCREASE IN RESISTANCE IN THIS CIRCUIT WILL BE INTERPRETED BY THE REGULATOR AS A LOW BATTERY AND IT WILL INCREASE THE CHARGE RATE IN AN ATTEMPT TO BRING THE BATTERY UP TO FULL.

IT IS POSSIBLE, IF THE RESISTANCE IS HIGH ENOUGH, THE ALTERNATOR WILL FULL FIELD; OR AS AN ALTERNATIVE, THAT THE REGULATOR WILL BELIEVE THAT THE BATTERY IS TOO LOW TO BE CHARGED BY THE ALTERNATOR AND COMPLETE SHUTDOWN WILL OCCUR. PLEASE REMEMBER THAT ANY CIRCUIT BREAKERS OR FUSIBLE LINKS IN THE SYSTEM THE CAUSE OF INCREASED RESISTANCE, AND SHOULD BE CHECKED CAREFULLY IF IT IS FELT THAT THERE IS A CHARGING PROBLEM.

FROM A JUNE 1993 NAVISTAR TECHNICAL INFORMATION BULLETIN, COMES A WARNING THAT WE HAD NEVER CONSIDERED, BUT WHICH APPLIES TO NOT ONLY THEIR VEHICLES BUT PROBABLY A LARGE NUMBER OF CARS ON THE ROAD. THEY WARN THAT SINCE RADIATORS AND THEIR SUPPORTS ARE OFTEN MOUNTED IN RUBBER TO EXTEND THEIR LIFESPAN, THIS CAN RESULT IN THE RADIATOR AND THE SUPPORTS NOT BEING ELECTRICALLY GROUNDED TO THE CHASSIS OF THE VEHICLE.ANY ELECTRICAL DEVISE MOUNTED TO THE RADIATOR OR SUPPORT MAY FIND ITS GROUND PATH THROUGH THE COOLANT TO THE ENGINE, WHICH IS GROUNDED. CURRENT THROUGH THE COOLANT WILL CAUSE ELECTROLYTIC CORROSION OF THE RADIATOR RESULTING IN RAPID RADIATOR FAILURE. THE DEGREE OF CORROSION VARIES WITH THE TYPE OF DEVISE AND THE LENGTH OF TIME THE DEVISE IS USUALLY OPERATED. ANY ELECTRICAL DEVISE MOUNTED TO THE RADIATOR OR A SUPPORT SHOULD BEINDEPENDENTLY GROUNDED TO THE CHASSIS USING A 10GA. WIRE, AND CARE SHOULD BE TAKEN TO MAKE SURE THAT THE PAINT IS REMOVED FROM THE CHASSIS WHERE THE STRAP IS ATTACHED.