280zrice Posted May 22, 2008 Share Posted May 22, 2008 test driving a 78 andwith lights on low beam smoke from behind the horn button, goes away when high beam , but no high beam? anybody ever had this happen ??? Quote Link to comment Share on other sites More sharing options...
zmaster Posted May 22, 2008 Share Posted May 22, 2008 I'm not an electrical genious, but I dfon't think that is a good thing. check the fuses to see if they are the correct amp rating, maybe the headlight fuse is too high an amp, and in result it is burning the switch. Quote Link to comment Share on other sites More sharing options...
hughdogz Posted May 22, 2008 Share Posted May 22, 2008 Remove the combination switch and try cleaning the contacts inside. Hope this helps... Quote Link to comment Share on other sites More sharing options...
ktm Posted May 23, 2008 Share Posted May 23, 2008 A little electrical lesson for the day. Smoke = heat = resistance. What this means is that you are seeing smoke (wire insulation cooking) because of very high temperatures in the wiring. The high temperatures in the wiring are caused by high resistance in the wiring and connectors. High resistance can be a result of poor contact between connectors either by gaps and/or dirt, corrosion of the wires/connectors, improperly rated wiring (unlikely), etc. Good luck. Quote Link to comment Share on other sites More sharing options...
280zrice Posted May 23, 2008 Author Share Posted May 23, 2008 thanks for the info Quote Link to comment Share on other sites More sharing options...
blueovalz Posted May 24, 2008 Share Posted May 24, 2008 That's the magic smoke, that onced released, the part never works again. Quote Link to comment Share on other sites More sharing options...
woldson Posted May 24, 2008 Share Posted May 24, 2008 ^^LOL! Smoke = heat = resistance << Yea if you want to call a shorted wire a resistor. Techniclly true but odd to think of it in that way. I.E. braker bar between battery terminals. Quote Link to comment Share on other sites More sharing options...
ktm Posted May 24, 2008 Share Posted May 24, 2008 No, it's not odd to think of it that way. It is increased resistance, either through dirty contacts, corrosion, etc., that causes the wire to overheat. Wires typically have less than 0.5 ohms of resistance in a circuit in a car. I am talking about measuring the resistance between the wire and the chassis ground. How else would you "think of it"? The reason you get smoke is due to heat. Heat is generated in the wire due to increases resistance in the wire caused by corrosion, dirty connectors, etc. Wire heats up and starts to cook the insulation. To think of it in a hydraulic analogy: if you have a smooth-walled (resistance) pipe and need to flow (current) X amount, you develop a given pressure. If you roughen the pipe wall (increase resistance), but need to flow (current) the same X amount, your pressure increases. Quote Link to comment Share on other sites More sharing options...
Brad-ManQ45 Posted May 29, 2008 Share Posted May 29, 2008 One of the best things you can do for your car and lighting is to put relays for the headlight circuits - takes the load off the combo switch and insures full voltage to the lights. Quote Link to comment Share on other sites More sharing options...
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