Pbassred Posted July 4, 2021 Posted July 4, 2021 I had a failed front brake switch. These things happen. What surprised me during testing is that the switch passes 3Amp while its off!. I would expect that a circuit would be cold until the leaver is pulled and current flows to the light, even if there was a relay in the circuit. What actually happens is that the circuit is active until the leaver is pulled and current stops. That must trigger the relay. So normally on instead of normally off. The switch is a standard part in many bikes so it must be a standard circuit. Does anyone know why? Quote
Stu Posted July 4, 2021 Posted July 4, 2021 I have never come across a switch that behaves like that! They are normally cold until you pull the lever Quote
husoi Posted July 4, 2021 Posted July 4, 2021 Even in normal operation you wouldn't have that type of current. 23W for 1 brake light does around 1.65A As @Stu says, when in rest the switch is open and no current are passing. You have a parallel switch circuit for the pedal but the current is the same and open circuit until actioned. You should check for some insulation being damaged. Quote
Pbassred Posted July 5, 2021 Author Posted July 5, 2021 No the switch is normally closed i.e. "on" when the brake leaver is not squeezed. I took it out and tested it on a multimetrer. That circuit could not work in any other way. I could be wrong about the actual current. I had to use the 20A setting as my small reading fuse is blown. However, the switch gets warm at rest while the brake light is off. That is definetly what is happening. I just can't figure out why. Quote
Pbassred Posted July 5, 2021 Author Posted July 5, 2021 I thought of that, but its a Honda VFR800 6 gen (2002 - 2009) so; no. Besides, there is no dash error light. I previously changed the side lite bulbs to LED which would usually throw a hissy fit. Its not just Hondas. Its common to Nissin master cylinders. Yamahas use it too. Quote
Stu Posted July 5, 2021 Posted July 5, 2021 11 hours ago, Pbassred said: No the switch is normally closed i.e. "on" when the brake leaver is not squeezed. I took it out and tested it on a multimetrer. That circuit could not work in any other way. I could be wrong about the actual current. I had to use the 20A setting as my small reading fuse is blown. However, the switch gets warm at rest while the brake light is off. That is definetly what is happening. I just can't figure out why. You are checking it right aren't you? as I have mad this mistake before in that when the switch is removed there is no pressure on the tab that operates the switch which makes the circuit Basically the lever holds the circuit open and once the switch is removed it then becomes closed Quote
fastbob Posted July 5, 2021 Posted July 5, 2021 Wouldn't it be a simple matter of replacing the switch ? Quote
Mississippi Bullfrog Posted July 6, 2021 Posted July 6, 2021 If you buy one of those eBay brake switches take it apart and put a smear of copper grease on the moving parts before fitting. They are assembled dry and since they are exposed to the elements don't last long before seizing up. The last one I replaced lasted a few weeks before sticking. After adding a small amount of grease it's worked fine in all weathers. Quote
iangaryprice Posted July 6, 2021 Posted July 6, 2021 23 hours ago, Stu said: You are checking it right aren't you? as I have mad this mistake before in that when the switch is removed there is no pressure on the tab that operates the switch which makes the circuit Basically the lever holds the circuit open and once the switch is removed it then becomes closed As above the switches seem to work the wrong way around when not installed. Not pressed - switch closed. Preseed switch open. 3.4 Amp is about right for the current draw. Most bigger bikes have 2 bulbs - 2 x 21w =42w /12v =3.5amp. Quote
Pbassred Posted July 9, 2021 Author Posted July 9, 2021 The last 3 posters have reinforced what I have been saying - the switch opens when you press it. The question wasn't about whether is does this, but WHY design a circuit like that.. The repair is simple. I already have the switch. The second odd thing is this it has stopped failing now. Quote
Stu Posted July 9, 2021 Posted July 9, 2021 8 hours ago, Pbassred said: The last 3 posters have reinforced what I have been saying - the switch opens when you press it. The question wasn't about whether is does this, but WHY design a circuit like that.. The repair is simple. I already have the switch. The second odd thing is this it has stopped failing now. Your first post says that the current is cut for the light to come on? Re reading what you have posted I think you have mixed it up a little The live feeds the switch then to the light and when the lever is idle the switch is pressed which cuts the circuit When you pull the lever it releases the pin activating the circuit The switch works the wrong way round so press the button it cuts the circuit releasing the switch makes the circuit 2 Quote
Pbassred Posted July 16, 2021 Author Posted July 16, 2021 No actually I did get it twisted. I had convinced my self that current was flowing when the switched was pressed. It also seemed to get warm. With further measurment I have found that the opposit is true. In fact my last post is arguing with myself. Literally; 2 wires, a bulb and a battery. Where is that facepalm icon when you need it? 2 Quote
Bender Posted July 16, 2021 Posted July 16, 2021 1 hour ago, husoi said: You mean this? Captain obvious Quote
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