Brake Lights works, tail light doesn't? By braketroubles (Read 18,352 times)

[braketroubles]

Ok so I have this scooter www.chineseatvonline.com/sunl-sl15021b-150cc-chinese-moped-owners-manual-p-12812.html?page=5

SUNL 150.

Anyways, are there any quick fixes you can think of for why my brake light works but my taillight doesn't? They both come from the same bulb, but for some reason it's not getting the message to be a tail light when i'm not braking. As you can imagine this is dangerous at night. We only have one scooter repair shop here and they are well... not the best. Any suggestions?

[dlallen]

I believe it is a dual fillament bulb. The taillight part is burnt out but not the brake light part.
Kind of like a headlight where low beam doesn't work but high beam does.

[braketroubles]

Well that was the first thing I thought too, but after replacing it with new bulbs twice i'm beginning to doubt my intuition.

[Bashan]

As dlallen described the bulb has two filiments and they have different circuits. Your brake light most likely has a green/yellow wire and the tail light is usually a brown. First check the connectors that the wires run to. It's usually a pigtail off of the light. Unhook it and make sure the contacts are in straight and the wires are good. It's not the green ground wire that's trouble since both filiments ground through it. If those things are good then you'll have to trace the brown back to the front. Refer to the wiring diagram below and you can see how the G/Y and brown wires connect. This PDF explains how to test the circuits from front to back usng a multimeter.

[braketroubles]

Ok this was very helpful thank you! I have determined that all the connections are good up until the brake light switches. I'm assuming that this was the problem and I have ordered some new ones here:

www.ebay.com/itm/BRAKE-LIGHT-SWITCH-LEFT-RIGHT-CHINESE-SCOOTER-GY6-50cc-GY6-150cc-QMB139-QMJ157-/200860710142#vi-content

Am I correct in assuming that if there is a complete circuit between the connectors going into the brake light switches and the light bulb port, that the problem is the switches linked above? The green/yellow makes a circuit with the back terminal of the brake light switch and the brown makes a circuit with the front terminal. It works for both the right and left switch. Is there anything else involved that i'm missing?

[jct842]

Brake light switchs do not have anything to do with tail light not working. Use your meter and find out why there is no 12 v on brown.

[Bashan]

It can be confusing, that's for sure. The two brake light switches are linked so that the bulb will light when either, or both handles are pulled. They energize only one filiment of the bulb when braking. The other filiment (in the same bulb) is energized by the tail light circuit through the brown wire. One confusing thing is that they share a common ground wire. An easier way to visualize it is think two seperate bulbs, one for the brake supplied by the G/Y, and one for the tail supplied by the brown. Ignore the brake circut, it's working, concentrate on where the brown runs. Then go at it with a multimeter set on continuity and test each aspect of the wire until you don't get a tone.

[adamt]

I have a 2021 bintelli sprint i had to remove the seat and all rear plastic. The tail light housing is attached to the 2 rear side panels. Make sure you put the bulb in the right way, it lines up differently than turn signals