04 Ninja 250 - no taillight, brake light circuit still works

ollie_on · October 20th, 2014, 07:01 PM

This is a weird one.

Ninja 250 taillight doesn't turn on but brake light still works. It was intermittent last week (friend said people told her it was off while she was riding) but now it just won't come on. I know they're on a separate circuit.

I measured the voltages at the socket contacts and we get 11.5-11.8 volts on the brake light circuit but only 7.5 volts on the taillight circuit. The wires look all right, nothing is rusty. Fresh bulb didn't fix anything. No fuses were dead.

I'm stumped, any ideas?

Ghostt · October 20th, 2014, 08:26 PM

Quote:

Originally Posted by ollie_on

This is a weird one.

Ninja 250 taillight doesn't turn on but brake light still works. It was intermittent last week (friend said people told her it was off while she was riding) but now it just won't come on. I know they're on a separate circuit.

I measured the voltages at the socket contacts and we get 11.5-11.8 volts on the brake light circuit but only 7.5 volts on the taillight circuit. The wires look all right, nothing is rusty. Fresh bulb didn't fix anything. No fuses were dead.

I'm stumped, any ideas?

You sir have a electrical gremlin, and the only way to get rid of it is extremely methodical troubleshooting.

Start at the socket, and work your way backwards, with not only the hot but the grounds as well.e
if the voltage is off that much then you have a bad connection somewhere.

Also double check EVERYTHING, don't assume something is ok.

JasonJ · October 21st, 2014, 04:34 AM

^ what Ghostt said. Starting at the socket where you know the voltage drop is measurable.. work backwards in that circuit until you find a spot (a fuse junction, wire splice, plug in connector, component, etc) where the voltage goes back up to normal.. now you've isolated the area where the voltage drop occurs. fix it.

If you find no such place, then it is a grounding issue and you can check the quality of your ground starting at the socket and working backwards.

October 20th, 2014, 07:01 PM	#1
ollie_on ninjette.org newbie Name: Alan Location: berkeley Join Date: Oct 2012 Motorcycle(s): '10 ninja 250 Posts: 1	04 Ninja 250 - no taillight, brake light circuit still works This is a weird one. Ninja 250 taillight doesn't turn on but brake light still works. It was intermittent last week (friend said people told her it was off while she was riding) but now it just won't come on. I know they're on a separate circuit. I measured the voltages at the socket contacts and we get 11.5-11.8 volts on the brake light circuit but only 7.5 volts on the taillight circuit. The wires look all right, nothing is rusty. Fresh bulb didn't fix anything. No fuses were dead. I'm stumped, any ideas?

October 21st, 2014, 04:34 AM	#3
JasonJ ninjette.org member Name: Jason Location: Bay City, MI Join Date: Apr 2014 Motorcycle(s): 1980 Yamaha XS850G Midnight Special, 32k Miles; 2000 EX250F, <5000 Orig Miles Posts: 98	^ what Ghostt said. Starting at the socket where you know the voltage drop is measurable.. work backwards in that circuit until you find a spot (a fuse junction, wire splice, plug in connector, component, etc) where the voltage goes back up to normal.. now you've isolated the area where the voltage drop occurs. fix it. If you find no such place, then it is a grounding issue and you can check the quality of your ground starting at the socket and working backwards.