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Switch resistance

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Old May 31, 2012 | 08:55 PM
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From: Idaho Falls
Switch resistance

Okay here is a quick question that is kind of dumb. I tested a switch running my off road lighting with a multimeter. The switch lit up but showed no resistance. Does this mean it is not functioning properly? Thanks for your time.
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Old Jun 1, 2012 | 03:43 AM
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A toggle switch will not have resistance (if so very little) unless you are pushing more power through it than what is rated for, which will create heat and burn up the switch. All it does is complete an electrical connection. But I'm not understanding how you are checking for resistance here.
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Old Jun 1, 2012 | 07:47 AM
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Define "no resistance". No resistance might mean 0 ohms (or resistance, 0 = no or none), or it might mean infinite resistance or no continuity:
- http://www.4crawler.com/4x4/CheapTri...oUseAnOhmMeter
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Old Jun 1, 2012 | 08:07 AM
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Checking with a multimeter. 0 OHMS reading but the LED lights up on the switch.
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Old Jun 1, 2012 | 08:48 AM
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0 ohms is a good reading for a closed switch. They usually have the internal LED wired to a ground connection and then when the switch closes and passes power to the load connection, the LED, that is wired in parallel with the load, lights up to show the switch is on.
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Old Jun 1, 2012 | 10:11 AM
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I was measuring the switch in the on position so should it be open at that point. The reason I though it was bad was because the OHMS didn't change from when they were touching nothing when I touched them to the switch. I'm new to a multimeter and just tryin to get some experience with it. Thanks for the input
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Old Jun 1, 2012 | 10:17 AM
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Originally Posted by Tomg303
I was measuring the switch in the on position so should it be open at that point. The reason I though it was bad was because the OHMS didn't change from when they were touching nothing when I touched them to the switch. I'm new to a multimeter and just tryin to get some experience with it. Thanks for the input
Read the web page section I linked above. It'll tell you how to use an ohm meter. Getting the same reading as when the probes are not touching anything is not 0 ohms, that is infinite ohms or an open circuit. There is no standard way of indicating infinite resistance, each meter will be different. But infinite ohms is that, infinite as is really really high resistance or an open circuit.

What you might try is using a piece of bare metal or wire and try touching the probes to that metal and see what reading you get. Or touch the probes together and that should be 0 or a short circuit.

It might be you were not touching the right contacts on the switch with the probes. They usually have a power, ground and load contact. Depending on how they are wired internally, the switch may connect the power contact to the load contact or it may connect the ground contact to the load contact when the switch is closed.
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