<VV> Meters vs Test Lights

[HallGrenn at aol.com]

In a message dated 8/8/2008 8:49:44 AM Eastern Daylight Time,  
FrankCB at aol.com writes:

Ken,
That's why you have to measure the voltage DROP  in  the wire going to the 
device with the device turned ON.  If  the wire or  connection cannot supply 
enough amperage, the voltage  will re reduced to the  point where it will be 
too 
low to allow the  device to function properly.   So measure voltage at the 
device  with it turned on.  If the voltage is  appreciably below 12 volts,  
then 
you have a problem in the line going to the  device OR possibly,  in the 
ground 
connection FROM the device.
Frank  Burkhard



Frank,  Very good point.  When I married I also acquired my  wife's Plymouth 
Duster 318--which had continual battery, alternator and  electronic ignition 
problems--every two years or so something would go  bad.  I found one bad 
connection in an engine multi-wire harness with the  wire that carried the heavy 
current from the battery/alternator back to the  dash--the connectors had gotten 
jammed and cocked instead of meshing during  vehicle assembly (car was 
purchased new).  The dealers never fixed it and I  stopped taking it in and just 
replaced parts to keep the thing running.  At  about 200,000 miles my wife called 
to say the car had died on the  highway--everything was dead, no lights, 
horn, ignition.  The through  firewall connector had the same problem with the 
same circuit--it had been  overheating for over ten years and finally gave out.  
If I or the dealer  had spent a couple of hours checking for voltage drop (or 
if the car had had a  voltmeter instead of an ammeter) we would have found 
both problems years  earlier.  Now that our cars are so much older I have found 
that voltage  drops point the way to solving most of my lighting and wiring  
problems.  Cleaning ground clips and screws and replacing corroded  connectors 
makes things work like new.  I use my voltmeter much more today  than twenty 
years ago.
 
Bob Hall



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