TECH TIP FOR FEBRUARY, 1996

REMEMBER THE ARTICLE ON THE CHRYSLER CHARGING SYSTEMS? WELL, IT'S COMING BUT IT'S A LOT HARDER TO GET TOGETHER THAN THE ORDINARY TECH TIP, AND BESIDES I'VE FOUND THIS GREAT ARTICLE ON THE FORD INTERNALLY REGULATED CHARGING SYSTEM. SO CHRYSLER IS COMING, BUT BE SURE YOU READ THIS PIECE ON THE FORD IAR.

FIRST, FOR AN EXTRA TECH TIP. WE RECENTLY WENT THROUGH A PROBLEM WITH A 1991 OLDS "98" ELITE, EQUIPPED WITH A 3.8L AND THE "HEATED FRONT WINDSHIELD" OPTION. THE CAR'S CHARGING SYSTEM WOULD INTERMITTENTLY START OPERATING AT ABOVE 18 VOLTS. AT FIRST IT WAS THOUGHT THAT IT WAS THE GAUGE THAT WAS FAULTY, BUT SEPARATE METERS CONFIRMED THAT IT WAS REALLY HAPPENING.

THE ALTERNATOR WAS REMOVE AND BROUGHT TO US FOR CHECKING, AND OF COURSE THERE WAS NOTHING WRONG WITH IT. EVENTUALLY IT WAS TAKEN OFF A TOTAL OF THREE TIMES AND A NEW REGULATOR AND ROTOR WERE INSTALLED OUT OF SHEER SPITE (READ DESPERATION). ONCE WE WERE SATISFIED THAT THE ALTERNATOR COULD NOT POSSIBLE BE AT FAULT THE CHECKS OF THE BATTERY AND WIRING INTENSIFIED.

THE CAR WOULD RUN PROPERLY FOR HOURS, BE SHUT OFF, AND AFTER RESTART, WITHIN MINUTES, MIGHT GO TO THIS HIGH CHARGE RATE, MAYBE! WE SUSPECTED THAT IT HAD SOMETHING TO DO WITH THE HEATED FRONT WINDSHIELD OPTION, WHICH WILL ALTER THE CHARGE RATE OF THE ALTERNATOR TO CLEAR THE WINDSHIELD, BUT AFTER THE CAR SHOWED THAT IT COULD OVER-CHARGE EVEN WITH THIS OPTION TURNED OFF, WE ABANDONED THAT LINE OF THINKING.

THE FINAL OUT COME A BAD GROUND IN THE ECM MAIN PLUG. THE PINS IN THE ECM HAVE WHAT APPEARS LIKE BURRS ON THEM TO HELP HOLD THE WIRE CONNECTOR IN PLACE. ON THE GROUND PIN IN THIS ECM THERE WERE NO BURRS AND THE CONNECTOR WOULD WIGGLE A LITTLE LOOSE CAUSING THE REGULATOR TO THINK THAT THE BATTERY WAS UNDERCHARGED AND THE RESULT WAS THE HIGH CHARGE RATE. SINCE THE ECM & WIRING CONNECTOR ARE PROBABLY FAIRLY STANDARD THIS COULD PROVE TO BE A PROBLEM ON OTHER GM VEHICLES.

SINCE THE REST OF THIS MONTH IS ABOUT THE FORD IAR ALTERNATOR, YOU KNOW, THE ONE WITH THE FLAMABLE PLUGS, I FELT THAT I SHOULD CLARIFY SOMETHING. WE SUPPLY NEW OEM PLUGS WITH EACH UNIT, AND HIGHLY RECOMMEND THAT YOU USE THEM; BUT!WE DIDN'T DESIGN THE ALTERNAOR, THE PLUG OR THE SYSTEM AND CANNOT THEREFORE BE HELD RESPONSIBLE FOR THE ORIGINAL OR FUTURE FIRES IN THE ALTERNATOR.

THE ARTICLE I AM GOING TO SHOW YOU TAKES ABOUT 10 PAGES WITH ITS VARIOUS DIAGRAMS. WITH THIS IS MIND, FROM A MAILING COST STAND POINT ALONE, I AM GOING TO BREAK IT UP INTO PROBABLY THREE MONTHS. BE SURE TO SAVE ALL OF THESE TIPS, SO THAT YOU GET THE COMPLETE STORY. A HINT!  THERE ARE THREE OTHER TECH TIPS TO BE FOUND WRITTEN INTO THE ARTICLE, BESIDES HOW TO HANDLE THE FORD IAR.

NOW FOR FORD IAR ALTERNATORS. THIS ARTICLE IS FROM JOHN THORNTON, PRO-TEC AUTO REPAIR INC., NAPERVILLE,ILL. MR.THORNTON IS A CONTRIBUTING EDITOR FOR THE AUTO ELECTRIC REBUILDERS EXCHANGE NEWSPAPER AND THE AUTOMOTIVE REBUILDER MAGAZINE. FOR THE MOST PART I AM GOING TO QUOTE MR. THORNTON.

HOW MANY TIME HAVE YOU HEARD SOMEONE SAY " THE ALTERNATOR IS BAD"?  THEN, "WHAT'S WRONG WITH IT"? THIS IS USUALLY FOLLOWED BY THE EVER INFORMATIVE " IT DOESN'T WORK".

I'VE ALWAYS SUBSCRIBED TO THE THEORY OF TESTING, THAT HELPS DETERMINE WHY A SYSTEM, CIRCUIT, OR COMPONENT FAILED. THIS TECHNIQUE HELPS ENSURE ACCURATE DIAGNOSIS

INSTEAD OF SAYING " THE ALTERNATOR IS BAD", I FIND IT PREFERABLE TO SAY ONE OF THE FOLLOWING:

1.) THE FIELD WINDING IS OPEN

2.) THE REGULATOR POWER TRANSISTOR IS OPEN OR FAILING

3.) THE RECTIFYING DIODES ARE ALLOWING EXCESS AC CURRENT INTO THE  CHARGING SYSTEM

THE PURPOSE OF THIS ARTICLE IS TO SHARE WITH YOU SOME OF THE IN VEHICLE TESTING TECHNIQUES, WE USE AT OUR SHOP WHEN EVALUATING FORD, IAR ALTERNATOR EQUIPPED, VEHICLES. THIS STYLE OF TESTINGPREVENTS MISDIAGNOSIS. IT'S EASY TO JUMP TO CONCLUSIONS IN A BUSY AND HECTIC SHOP ENVIRONMENT. A CAR COMES IN WITH A CHARGING PROBLEM, AND A LOAD TEST SHOWS LITTLE OR NO OUTPUT. MUST BE A BAD ALTERNATOR, RIGHT. MAYBE, MAYBE NOT. PLANNED, SPECIFIC TESTING APPROACH WILL VERIFY THE DIAGNOSIS.

LET'S START BY EXAMINING FIGURE 1. THIS SIMPLIFIED DRAWING SHOWS THE TYPICAL IAR REGULATOR, WIRING AND COMPONENT RELATIONSHIP. TERMINAL"I" AT THE REGULATOR PLUG IS THE IGNITION TURN ON. TERMINAL "S" IS THE STATOR SIGNAL INPUT TO THE REGULATOR, AND TERMINAL "A" IS BOTH SENSE AND THE FIELD CURRENT SOURCE. ALTHOUGH FIGURE 1 DOESN'T SHOW IT, THE REGULATOR IS GROUNDED THOUGH IT'S CASE AND MOUNTING FASTENERS. AT THE BACK OF THE REGULATOR ARE TERMINAL (FASTENERS) "A" AND "F". "A" IS THE SAME AS "A" IN THE REGULATOR PLUG (SENSE AND FIELD CURRENT SOURCE), AND "F" IS THE FIELD CONNECTION POINT IN THIS AªCIRCUIT REGULATOR.

THERE IS NOT MUCH TO BE SAID ABOUT THE HIGHLY PUBLICIZED BBS OUTPUT PLUG CONNECTOR. OUTSIDE OF THE DOTTED LINE IN FIGURE 1 IS THE BATTERY, IGNITION SWITCH, FUSE, AND WARNING LAMP. DEPENDING ON THE APPLICATION, THE WARNING LAMP CAN COME ON WHEN SENSE VOLTAGE (TERMINAL "A") IS TOO HIGH OR TOO LOW, AND/OR IF THERE IS A STATOR PULSE PROBLEM AT THE "S" TERMINAL.

PLEASE STUDY FIGURE 2, WHICH IS MY SIMPLIFIED DRAWING OF WHAT IS INSIDE AN IAR REGULATOR. WE WILL USE FIGURE 2 AS OUR ROAD MAP FOR MANY OF THE CIRCUIT CHECKS.

THE FIRST GROUP OF TESTS IS PERFORMED WITH THE IGNITION OFF. MEASURE THE VOLTAGE AT TERMINAL "A" OF THE REGULATOR WITH THE REGULATOR PLUG CONNECTED. WHAT DO YOU EXPECT TO FIND? THAT'S RIGHT! BATTERY VOLTAGE, WHICH SHOULD BE ABOUT 12.6 VOLTS. WHERE ELSE COULD YOU MAKE THIS MEASUREMENT? TERMINAL "A" ON THE BACK OF THE REGULATOR, WHICH IS WHERE I USUALLY GO FIRST. A CAREFUL LOOK AT FIGURE 2 WILL SHOW A CONNECTION BETWEEN THESE TWO POINTS.

NEXT, GO TO TERMINAL "F" ON THE BACK OF THE REGULATOR AND MEASURE THE VOLTAGE AT THIS POINT. WHAT DO YOU EXPECT TO FIND HERE? LET ME GIVE YOU A CLUE. WITH THE IGNITION OFF, THE FIELD POWER TRANSISTOR IS TURNED OFF. IF THAT'S THE CASE, THERE WILL BE APPROX. 12.6 VOLTS AT "F" SINCE THE CIRCUIT IS OPEN AT THE POWER TRANSISTOR. SUPPOSE YOU MEASURED 12.6 VOLTS AT "A" AND 1 VOLT AT "F", WHAT WOULD YOU KNOW? THE FIELD CIRCUIT IS TURNED ON. SHOULD IT BE WITH THE KEY TURNED OFF? NO, IT SHOULDN'T. SOMETHING HAS KEPT IT TURNED ON. SOUNDS LIKE A REGULATOR PROBLEM, DOESN'T IT.

BE AWARE THAT FORD HAS ISSUED A BULLETIN REGARDING THIS VERY CONDITION. FORD BULLETIN # 94/9/11 AFFECTS 1993 & 94 RANGERS. IF THE BLOWER IS IN OPERATION WITH WHEN THE IGNITION KEY IS SHUT OFF, AN INDUCED VOLTAGE WILL BE BACK-FED INTO THE REGULATOR THROUGH THE ALTERNATOR WARNING LAMP CIRCUIT, SPECIFICALLY FUSE# 9 IN THE PANEL. THIS WILL LEAVE THE REGULATOR TURNED ON WITH THE KEY OFF. OBVIOUSLY, THIS CURRENT DRAW ON THE BATTERY WILL EFFECT STARTING PERFORMANCE. THE FIX? A $16.00(US) KIT THAT CHANGES THE FEED FROM FUSE# 9 TO FUSE# 7.

ASIDE FROM ODDBALL SITUATIONS; WHEN THE KEY IS OFF, THE FIELD CIRCUIT IS OFF. IF IT'S NOT, SUSPECT A REGULATOR PROBLEM. SUPPOSE THAT YOU MEASURE 12.6 VOLTS AT "A" AND NOTHING AT "F". WHAT HAVE YOU FOUND? LOOKS LIKE THERE IS AN OPEN IN THE ROTOR OR A PROBLEM WITH THE BRUSHES.

THE NEXT TEST TO PERFORM WITH THE KEY OFF IS A RESISTANCE MEASUREMENT OF THE ROTOR AND BRUSHES. THIS WILL VERIFY THE PREVIOUS SCENARIO. DISCONNECT THE PLUG FROM THE REGULATOR, AND PUT YOU OHM METER ACROSS "A" AND "F" ON THE BACK OF THE REGULATOR. FORD'S SPEC IS 2.4 OHMS MINIMUM.

NOTE!I HAVE TESTED GOOD ALTERNATORS WITH RESISTANCE READINGS IN THE 2.2 - 2.3 OHM RANGE.

THE SECOND GROUP OF TESTS IS PREFORMED WITH THE KEY ON, ENGINEOFF (KOEO). USING A "T PIN" OR A "J HOOK" MEASURE THE VOLTAGE AT THE "I" (LAMP) TERMINAL OF THE REGULATOR PLUG. PLEASE REMEMBER, THE CONNECTOR IS PLUGGED IN. THE WARNING LAMP ON THE DASH SHOULD BE ON. READINGS TYPICALLY FALL IN THE 2/3 VOLT RANGE WITH 1 VOLT BEING THE MINIMUM. A PROPERLY OPERATING LAMP CIRCUIT ALLOWS THE FIELD CIRCUIT TO TURN ON. LOOK AT FIGURE 2 AND YOU WILL SEE A CONNECTION BETWEEN THE LAMP DRIVER AND THE SWITCH CONTROL. IF THIS 2/3 VOLTS IS NOT PRESENT WITH THE KEY ON THE FIELD CIRCUIT WILL NOT TURN ON.  NO FIELD, NO CHARGE.

NOW MEASURE THE VOLTAGE AT THE "F" TERMINAL ON THE BACK OF THE REGULATOR. ASSUMING THAT THE FIELD DRIVER (TRANSISTOR) IS TURNED ON, WHAT SHOULD YOU EXPECT TO MEASURE? WE SHOULD BE MEASURING THE VOLTAGE DROP (SATURATION VOLTAGE) ACROSS THE POWER SWITCHING TRANSISTOR. ONE VOLT IS TYPICAL, FORD EVEN HAS A SPECIFICATION FOR THIS CHECK; IT IS 1.5 VOLTS.

IF YOU WERE TO MEASURE 12 VOLTS AT "F" WITH THE KEY ON, WHAT WOULD BE YOUR NEXT STEP? THINK ABOUT IT FOR A MOMENT. IT WOULD SEEM THAT WE HAVE AN OPEN SWITCHING TRANSISTOR, THEREFORE A FAILED REGULATOR. BEFORE THE REGULATOR IS CONDEMNED, WE WOULD HAVE TO MAKE SURE WE HAD A GOOD GROUND CONNECTION BETWEEN THE REGULATOR, ALTERNATOR AND THE NEGATIVE TERMINAL OF THE BATTERY.

CHECKING THE VOLTAGE AT "F" IS ALSO USEFUL FOR ANOTHER REASON. ELECTRONIC DEVISES TYPICALLY ARE NOT GOOD ONE DAY AND BAD THE NEXT. OVER TIME THE PERFORMANCE OF SOLID STATE DEVISES CAN DEGRADE. IT IS POSSIBLE TO DETECT IMPENDING FAILURES BEFORE THEY OCCUR. CHECKING THE VOLTAGE AT "F" IS A GOOD EXAMPLE OF THIS. SUPPOSE YOU WERE TO MEASURE 1.7 VOLTS AT THIS TERMINAL. I'VE TOLD YOU THAT THE TYPICAL READING IS 1 VOLT AND THAT THE FORD SPEC IS 1.5 VOLTS. WILL THIS ALTERNATOR STILL CHARGE? WILL THE CUSTOMER HAVE A COMPLAINT? THE ANSWERS ARE YES AND NO RESPECTIVELY. THE REGULATOR'S PERFORMANCE IS STARTING TO DEGRADE. THIS IS AN EYE OPENING AND INFORMATIVE CHECK TO MAKE ON ALL "GOOD" CHARGING SYSTEMS. I HAVE SEEN SIMILAR CONDITIONS IN IGNITION MODULES AND ENGINE COMPUTERS.

THE LAST CHECK IN THIS GROUP OF TESTS IS TO MEASURE FIELD CURRENT. PREVIOUSLY WE WERE MEASURING VOLTAGE AT "F". SO LEAVE YOUR METER LEADS CONNECTED, SWITCH JACKS ON YOUR DVM TO AMPS AND TURN TO THE AMPS RANGE ON YOUR METER. YOU WILL NOW BE MEASURING FIELD CURRENT. THIS IS MORE ACCURATE THAN USING THE OHM METER TO CHECK THE ROTOR AND BRUSHES. TYPICAL READINGS ARE 3.5 - 5.5 AMPS. LESS FIELD CURRENT THAN THIS WILL CERTAINLY EFFECT OUTPUT CURRENT.

THE THIRD AND FINAL GROUP OF TESTS ARE PERFORMED WITH THE ENGINE RUNNING. BEFORE WE GET TO THEM, LET'S REVIEW WHAT WE HAVE DONE. WE HAVE VERIFIED THE REGULATOR IS GETTING WHAT IT NEEDS FOR PROPER OPERATION (CORRECT VOLTAGES AT "I" AND "A"). THE REGULATOR FIELD IS ABLE TO TURN OFF AND ON PROPERLY. POWER TRANSISTOR SATURATION VOLTAGE (ABOUT 1 VOLT) APPEARS TO BE GOOD. FIELD CURRENT IS WITHIN SPEC (3,5-5.5 AMPS). IF YOU THINK ABOUT WHAT WE HAVE DONE, I HOPE YOU WILL AGREE THAT WE KNOW QUITE A BIT ABOUT THIS CHARGING SYSTEM, AND WE HAVEN'T EVEN STARTED THE VEHICLE.

OUR FIRST RUNNING TEST IS MEASURING THE VOLTAGE AT "A". THIS IS SENSE VOLTAGE AND SHOULD BE CLOSE (WITHIN .2-.3 VOLTS, WITH THE ALTERNATOR PRODUCING 20-25 AMPS) TO THE ALTERNATOR'S AND BATTERY'S POSITIVE POST VOLTAGE.

"I" (WARNING LAMP) VOLTAGE IS APPROX. 14 VOLTS (CHARGING SYSTEM VOLTAGE). THIS OPPOSING VOLTAGE WILL TURN THE WARNING LAMP OFF. THIS IS ACCOMPLISHED WHEN THE REGULATOR SEES A SIGNAL FROM THE STATOR AT THE "S" TERMINAL. THIS IS OUR NEXT CHECK. MEASURE THE VOLTAGE AT THE "S" TERMINAL IN THE REGULATOR PLUG. YOUR METER SHOULD READ APPROX 6-8 VOLTS. THIS IS A NON-RECTIFIED SINGLE PHASE PULSE. SEE FIGURE# 3, AND NOTICE AMPLITUDE OF THE SIGNAL GOES FROM 15 VOLTS TO A NEGATIVE 1 VOLT. YOUR METER WILL DISPLAY AN "AVERAGE" OF THIS SIGNAL. WITHOUT THIS SIGNAL TO THE REGULATOR, THE WARNING LAMP WILL NOT TURN ODD, ALTHOUGH THE ALTERNATOR MAY BE OPERATING PROPERLY.

(IT IS BEST TO USE A LAB SCOPE TO MAKE THE REST OF THE TESTS, AS A SHOP SCOPE, USING A INDUCTIVE PICK-UP WILL BE DIFFICULT)

NOW, LET'S RE©EXAMINE THE "F" TERMINAL. SEE FIGURE# 4. WE ARE LOOKING AT A RECTANGULAR WAVE. WHEN THE SIGNAL IS HIGH AT 15 VOLTS, THE REGULATOR'S POWER TRANSISTOR (FIELD DRIVER) IS TURNED OFF. WHEN THE SIGNAL IS LOW AT 1 VOLT, THE POWER TRANSISTOR IS TURNED ON AND FIELD CURRENT IS FLOWING. NOTICE THE CLEAN SIGNAL. ITS CORNERS ARE SHARP THE TRANSISTOR TURNS ON AND OFF CLEANLY, WITHOUT HASH OR ELECTRICAL NOISE. CAREFULLY EXAMINE FIGURE 5 AND COMPARE IT TO FIGURE 4. BELIEVE IT OR NOT THIS CAR ACTUALLY DROVE IN. OBVIOUSLY THIS DEPICTS A BAD REGULATOR. THE SCOPE MAKES IT VERY CLEAR. THE VOLTAGE LEVELS ARE WRONG, THE CORNERS ARE NOT SHARP, AND THE REGULATOR ON TIME HORIZONTAL LINES ARE WAVY.

AT THIS POINT IN OUR TEST PROCEDURES WE SHOULD PERFORM OUTPUT AND VOLTAGE DROP TESTS. AS THESE ARE PRETTY STRAIGHTFORWARD I'LL SKIP TO THE LAST TEST WE PERFORM WITH THE ENGINE RUNNING; MEASURING AC VOLTAGE, SOMETIMES CALLED RIPPLE.

PLEASE EXAMINE FIGURE 6. THIS IS AN EXAMPLE OF NORMAL AND ACCEPTABLE RIPPLE. THE AC HUMPS ARE UNIFORM AND ARE BELOW .350 VAC RMS. EXCESSIVE RIPPLE INDICATES A PROBLEM WITH THE DIODES &/OR THE STATOR. BESIDES REDUCING CHARGING OUTPUT, EXCESSIVE RIPPLE CAN CAUSE DRIVEABILITY PROBLEMS. LOOK AT FIGURE 7. THIS WAS TAKEN FROM A 1986 COUGAR ( THIS IS NOT AN IAR ALTERNATOR). THE CUSTOMER'S COMPLAINT WAS INTERMITTENT ROUGH IDLE. AFTER SPENDING MORE TIME THAN I SHOULD HAVE , I STUMBLED ACROSS THE CAUSE.... EXCESSIVE ALTERNATOR RIPPLE. CHARGING VOLTAGE WAS GOOD AND THERE WASN'T A CHARGING COMPLAINT, SO I ELIMINATED THE ALTERNATOR FROM MY MIND. I DON'T MAKE THAT MISTAKE ANY MORE, AND I HOPE YOU WON'T EITHER.

FINALLY, TAKE A LOOK AT FIGURE 8. THIS IS AN INJECTOR PATTERN FROM A 1988 FORD TAURUS WITH A 3.0L ENGINE. NOTICE WHAT IS RIDING ON THE INJECTOR OFF SIGNAL (APPROX 15 VOLTS). THAT'S RIGHT. EXCESSIVE RIPPLE. AT 1700rpm WITH AN ELECTRICAL LOAD OF ABOUT 40 AMPS, I MEASURED 1.5 VAC RMS ON MY METER. THIS IS ANOTHER EXAMPLE OF A VEHICLE IN WHICH THE CUSTOMER DID NOT PERCEIVE A CHARGING PROBLEM.

ACCURATE TESTING TELL US MORE THAN " THE ALTERNATOR ISN'T WORKING" AND "IT DOESN'T WORK". A PLANNED SPECIFIC TEST APPROACH WILL CONFIRM YOUR DIAGNOSIS.

HOW'S THAT? THIS IS THE TYPE OF TIP I'VE WANTED TO FIND FOR SOME TIME. AS A REBUIDLER, I SHOULD TELL YOU; THAT SOME ALTERNATOR MANUFACTURERS, IN ORDER TO GET BETTER OUTPUT AT IDLE, ARE RECTIFYING THE WHYE CONNECTION OF THE STATOR. THIS PRACTICE WILL LEAD TO HIGHER THAN EXPECTED RIPPLE SIGNAL UNDER LOAD, AND SHOULDNOT BE CONFUSED WITH A DEFECT.

THE NIPPONDENSO ALTERNATORS USED ON HONDA AND TOYOTA ARE PARTICULARLY SUSCEPTIBLE TO THIS.