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Discussion Starter #1
Hey guys, I have a set of fog lights on my brothers bike that finally went out. The switch is good, ohm'ed it out, 12.67 dc volts to ground, I just can't get the lights to fire up and they are brand new lamps. The ground is good via the tester and I have power ( 12.67 volts ) .....even when I hook up the lights directly bypassing the switch nothing happens.
Any ideas ????? :DeadHorse:


Thanks
 

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Gypsy on Parade
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4,772 Posts
It sounds like there could be a short in the housing. Maybe the socket is grounding to the lamp case?
 

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Discussion Starter #4
Southernman, I had even taken the light socket assembly out of the housing and jumped the ground and power directly to it...no go. I still read 12.67 volts to engine ground but I can't get the lamp to burn.
 

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Retired citizen
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I would test resistance from each wire lead to the socket contact and the socket itself. The contact would be the hot and the socket would be ground. That would confirm or eliminate open circuits. If you find an open circuit, that's the problem.
 

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Like Schmidtys says, an open or partially open circuit can fool you. It is possible to measure 12.5 volts at the socket with no load and have a corroded connector causing a high resistance "open" in between the voltage source and the socket. With no load (bulb), you see the full voltage; install the bulb and the voltage divides between the high resistance open and the bulb, causing low voltage at the bulb. For the sake of discussion, you will see "half" of the voltage at the bulb and the other half where the problem is.
 

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You need to check the voltage, on the sockets, with the bulbs in the sockets. Of course the bulbs need to be good. With the bulbs in the socket they put a load on the circuit, if there's high resistance in the circuit, the voltage will drop to unusable with the load.
 
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