[AT] Tractor lighting puzzler

[Phil Auten]

John,
Each light was using the other light as a ground return.
I witnessed the same thing with the wiring on my father-in-law's boat 
trailer many years ago.
We were checking the lights out without connecting the trailer to the 
vehicle's trailer hitch.
The regular lights seemed to work ok, but did seem a bit dim. When we tried 
to check the
turn signals, WOW, all the lights flashed together! After puzzling that for 
a while, we hitched
up the trailer and everything worked as it was supposed to. Like Farmer 
says, check the grounds!

Phil

At 03:22 PM 11/7/04, you wrote:
>This is a good one.  I installed two new low beam and two new high beam 
>headlights on my MF 175--one each on each fender.  The low beams and high 
>beams each had their separate wiring to the light switch.  They are wired 
>so in switch position 1 only the low beams come on; in switch position 2 
>both high and low beams come on, and in switch position 3 only the high 
>beams come on.  The first time I tried them the lights on the right fender 
>worked according to plan, but in ALL switch positions the lights on the 
>left fender BOTH came on VERY dim--together.  Obviously the right fender 
>was not grounded good enough so I added a ground wire from tractor frame 
>to the fender--which cleared up the problem..       The puzzler to me 
>is--before I grounded the right fender why did BOTH lights on the right 
>fender come on (very dim) even with the switch energizing only one circuit 
>(high or low beam)??????????????        Electricity always has been a 
>"challenge" to this old guy!    John
>
>                    In the wide-open spaces of NE Oregon