Wiring the rear light for brakes - 2000 kawasaki KLX 300

You have a short in the cross over wire. Almost all cars and trucks have one main break wire with a second wire "y" in off to the passenger side . You could just wire in a cross over and disconnect the old one.

Need to know year make and model. There is no fusable link. There will be a brake light fuse only

The high mount brake light gets its own signal from the brake light switch (on the brake pedal). Or at least the wire leaving the brake light switch will splice, one wire to the high mount brake light, and the other for the rear brake lights is routed through the turn signal switch, and coordinated there with the turn signal wires to the rear brake lights. The brake wires and turn signal wires share the same wire, and same filament in the bulbs. It is kind of complicated, but brakes applied with no turn signal, brake light wire goes from brake light switch through the turn switch and out to the bulbs. If brakes applied with turning signal, non blinking brake light wire goes from turn switch to rear light, while the turning signal wire will go through the flasher relay, and then to the rear light to cause blinking.

I hope that makes sense. It appears the problem may be in the turn signal switch for both the turn signals and the rear brake lights.

Hi, Hank before diagnosing any brake light issue always check the bulb and fuse first for integrity a brake light staying on is usually caused by the front brake light switch, which is mechanical, not disengaging. In early models moving the throttle control housing closer to the front brake master cylinder is the main fix. On late models, the switch gets tweaked and needs to be realigned. A brake light that does not come on when the brake lever is applied can be caused by a faulty switch or no continuity in the wiring at the switch. The rear brake light switch is hydraulic and it is extremely rare to malfunction in a closed circuit condition causing the brake light to stay on. Usually, rear brake light switch issues are caused by no brake pedal free play or a sticky rear master cylinder piston. A brake light that does not come on when the rear brake pedal is depressed can be caused by a faulty switch, air contamination in the brake line, or no continuity in the wiring at the switch. Finally, most tail light wiring harnesses run under the rear fender held in place by spot-welded clips. Worn out rear shocks or lowered suspension can bottom out causing the rear tire to come in contact with the wiring harness, rubbing the insulation off, exposing the bare metal inner core, allowing it to break or short out.
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It sounds like the rear brake pressure switch is bad. The wires for the front brake light switch are wired in parallel to the this switch. Replace the pressure switch in the metal brake line coming from the rear brake master cylinder going to the rear brake caliper.

Good Luck
Steve

Check the wires on the rear brake light switch. Follow the metal tube brake line coming out of the rear master cylinder going towards the rear wheel. You'll come to a pressure switch. This is the rear brake light switch. Check to see if the wires are still plugged onto the switch. One set of wires should be "hot" whenever the switch is on. The front brake light switch is simply wired in parallel with this switch.

Good Luck
Steve

one wire is 12 volt power all the time weather the key is on or not, the other wire goes to the turn signal switch on most models, ( you did not give your year or model ) , if the car uses the rear turn signals as brake lights also then the wire goes threw the turn signal switch, if the car has a separate turn signal bulb in the rear ( usely has amber lens in the rear ) then the second wire from the brake light switch goes to the BCM ( body control module ) and the BCM turns the brake lights on.

Check to see if the brake light works when you apply the front brakes. If they work but if the brake light won't come on when the rear brake pedal is depressed, the rear brake light switch is bad. Find the rear brake master cylinder and you'll see a metal line coming out of it. Follow the line back towards the rear of the bike until you come to a tee in the line. The brake light switch is screwed into the tee and a couple of wires plugged onto it.

If neither your rear brake light nor you tail light works, first check the bulb. If the bulb is good, you might have a wiring problem. The wiring is a sub-harness that plugs up under the seat area and then runs back to the rear light assembly. The turn signal wiring usually run down each side of the rear fender behind the fender struts.

Ride Safe
Steve

Yes , The wiring in question does effect the brake lights because they all run on the same circuit.
I would repiar or repalce all the wiring and then replace the brake light switch. The switch could have shorted out from the fire.

no disrespect but....
Check the book and make sure you are using the proper bulbs on all sides. (3957 looks just like 3956 but wont work right)