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Brake light is 12-14v dc but tail light is 24v AC?

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Keep blowing bulbs and put multi meter on and brake light is 12/14dc but the tail light wire is 24v AC ... Is there 2 rectifiers one behind headlight and one under tank?

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Incandescent light bulbs are not current specific (i.e., AC vs DC).  You need a voltage regulator, which used to be optional.  My old XR250 did this when I replaced the incandescent headlight bulb with a halogen bulb.

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But why does the headlight and tail light produce AC current but the brake light is dc current ? I thought the rectifier changed from AC to dc and the regulator reduced the power , near headlight there's a box says 12v rectifier , so does that mean the box under tank is the regulator ?

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There's what looks like a reg and rec behind headlight and also one under tank , is one for blinkers and brake light and another one for head light and tail light ? Put the multi meter on the socket for trail light And brake light is all sweet 12v dc but the tail light is 24v ac

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A rectifier converts AC to DC,  A regulator controls voltage.  A reg/rec does both.  I don't see a problem with some lights being AC and some DC.  Some conversions are like that.  24 volts sounds like a problem.  Is this bike factory street-legal or converted? 

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Yeah, i'd say 24v is a problem. In your other thread you say there is no battery in the system. If running any lights on DC you should have a battery or capacitor to smooth out the power. Your lights then get fed from the consistant power of the battery and the battery gets fed/charged by the output coming from the rectifier.

Right now, sounds like eveything DC is getting fed directly from the rectifier and any components connected to it will see any spikes coming from it.

Something in the ac circuit is not wired right or the regulator is not working right if you're getting 24 v.

Another thing that seems odd to me is that the brake and tail lights are different types of voltage, but both light filaments are in the same bulb, unless your setup has two different bulbs, one for brake and other for tail.

Edited by Trailryder42

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No same bulb , weird isn't it , blinkers are fine aswell , where is the rec reg at under the tank or is it the one behind headlight

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On US bikes the stock regulator is the one hanging from the center frame tube under the tank.

Are you sure you measured the voltage at the bulb receptacle properly for it to show one side dc and the other ac? Never heard of that before. Strange for sure.

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And there's one under the tank aswell but doesn't have anything written on it , I'm thinking there's one for blinkers and brake light and seperate one for headlight ands tail lights ? Because blinkers are showing correct voltage aswell

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Ohk found my answer the headlight is reg and rec for blinkers and brake light and the under tank one is reg only that's just for headlight and tail ImageUploadedByThumper Talk1400457395.755615.jpg

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Yes and ? The dc circuit is fine , it's just the one under the tank putting out 24v ac for the headlights and tail light that is the problem

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I'd say because the head and tail lights are always on and their current draw is a constant. Brake and blinkers are off until actuated, resulting in a sudden current draw and voltage drop. That's why running a battery or capacitor in the dc system is recommended, to stabilize and help prevent the sudden voltage drop when the brake and blinkers are actuated, so you get an immediate response and full illumination of the lights when activated.

The lights don't have to draw from the available current the bike is making at the moment of activation, they draw it from the storage unit where the power is already there at the proper voltage.

Sounds like you need a new regulator then. If it is connected to the system with the stock connectors and wiring hasn't be altered, then it shouldn't be a problem with being wired into the system wrong.

Do you have a Mate with a bike you can swap out his reg for to experiment with?

But why does the headlight and tail light produce AC current but the brake light is dc current ?

Edited by Trailryder42

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