Hi, I noticed today while riding my 150 cc scooter that my headlight was dim. when I applied the brake the light got bright again. Any ideas of what could be wrong?

 

That's a new one.

Is this intermittent, or does it do this all the time?

I'm not sure how accessable the wiring harness and connectors are on your scooter, but if the battery is at 12 volts and the light is dim then a lot of voltage drop is happening somewhere. When you have a big voltage drop *and* current flowing (the headlight is putting out some light proving that some current is flowing) power is being wasted big time (as in heat). Turn the headlight on and while it is "dim" feel around for hot spots in the wiring. You may get lucky and have the bad connection accessable to your fingers. Hot connections are bad connections.

If you can't find it then find a voltmeter. Measure the following DC voltages while the headlight is on *and* dim:

1) What is the voltage from the battery positive terminal to the battery negative terminal?

2) What is the voltage from the battery positive terminal to the headlight socket positive side?

3) What is the voltage from the battery positive terminal to the headlight socket ground side?

4) What is the voltage from the battery negative terminal to engine/frame ground.

5) When you step on the brake and the headight gets bright, which measurements above (1-4) changes? And by how much?

What kind of scooter? What is the engine size?

 

Lynn, It happens all the time. I will work on your list of questions and get back to you. thanks, bob

 

Thats funny my car does that too. All the lights will be dim at low idle, its a power conservation thing, when you rev it up they get bright again. Man, your funny