Seeking help with auto headlight electrical problem

[Fred W]

[Getting back on topic: One thing I don't understand is how you could have measured -12V anywhere on a bike that has no negative power supply. Everything on a motorcycle is ~ +12V with the negative side being grounded.

Could it be that you reversed your test leads on that JB?

Hi Fred, the headlights he is testing are on a Nissan Car.

The terminal that is used for ground on the headlight bulb is connected to power and the filiments are grounded by the headlight switch. So if he had the negative lead of his volt meter connected to the center terminal and the positive lead connected to one of the other terminals he would read negative voltage.

It will be important for Hans to check the available voltage with the headlight connected as the load of the headlight will make bad connections more apparent. The idea is, you could have 12volts of electrical pressure but a bad connection chokes down the flow enough to not light a big light.

But hell you knew that, so I was just explaining it so Hans might get an idea what to check.

Hehe, shucks, yes, I did know that. And I knew it was a car and not a bike, too. But that doesn't negate the lack of a negative voltage. And that you knew...

 

[James Burleigh]

But hell you knew that, so I was just explaining it so Hans might get an idea what to check.

Uh, right. I'm on it.... :blink:

 

[odot]

Holy rats nest/spagetti-O's........only one fix for that.

A gallon of gas and a match.