Using a multi-meter to test handlebar switches

[GeorgeOC]

Hello everyone, I am attempting to get a head start on some work for the weekend. Looking to make a dent in a re-wire. I want to rule out and errors or wire color mis-matches when comparing the stock diagram, and the replacement switches I have lined up...

Is there a chance anyone has experience using a multi-meter to test switch buttons etc, basically to find which wire is actually which? If anyone might have advice for this novice, i'd be in your debt.

Thanks in advanve for any replies!

 

[fredintoon]

Hi George,
if you don't have a circuit powered up, use the lowest Ohms (resistance) setting to check that circuit's continuity.
If a circuit IS powered use the 20VDC setting to see where the power is going.
Of course, if the circuit is powered and it's bulb lights up and goes out when the switch is flipped that circuit don't need no steenkin' multi-meter.

 

[GeorgeOC]

Hi George,
if you don't have a circuit powered up, use the lowest Ohms (resistance) setting to check that circuit's continuity.
If a circuit IS powered use the 20VDC setting to see where the power is going.
Of course, if the circuit is powered and it's bulb lights up and goes out when the switch is flipped that circuit don't need no steenkin' multi-meter.

Thank you Fred, much appreciated. The switches are not powered... at least I don't think so. Stock replacements for a 76'. In order to check continuity, doesn't one need two ends of the wire? In the form of a switch, my main hiccup is that only one end of the wire is exposed. the switch itself is the other end. Where I am drawing the blank is where to physically place each test lead...?

 

[DanielBlack]

George, each switch will have a feed to the switch and a send to a device. For example, the turn signals. You'll see a Br/W wire going to that. When switched to Left, the switch is making contact between the Br/W and Ch wires. That's your two ends. Br/W to the switch, the switch makes the connection, Ch out of the switch. Touch one lead to Br/W, the other to Ch. Switched to the Right, you'll see continuity between Br/W and Dg.

 

[MaxPete]

Right - DB has certainly outlined the process very well George.

The other key is to use the wiring diagrams and focus closely on the schematics of the switches. You should be able to follow a given wire from the headlight bucket and see what other wire it connects to when you move a given switch. Then you connect one of the leads from the meter to the first wire and the other lead to the second wire - and push the switch.

If the needle on an analogue meter swings to zero ohms (or the number drops to zero on a digital meter) when you push the switch - you've got a continuous circuit.

The beauty of this type of testing is that you really cannot damage anything because the only power in the circuit is that provided by the little battery in the meter itself.

 

[DanielBlack]

+1 on the diagram.

Also, I usually turn the beep off on my meter because it's kind of annoying and the tests I've doing recently need actual resistance readings. The tests you are doing are binary; continuity or no continuity. I'd use the beep here.

 

[fredintoon]

Thank you Fred, much appreciated. The switches are not powered... at least I don't think so. Stock replacements for a 76'. In order to check continuity, doesn't one need two ends of the wire? In the form of a switch, my main hiccup is that only one end of the wire is exposed. the switch itself is the other end. Where I am drawing the blank is where to physically place each test lead...?

Hi George,
If the switch is connected to the bike's battery use the Volts setting to look for power.
From what you say, I suppose you have a replacement switch with wires coming out of it (surely more than ONE wire?) that are colored differently than those in your wiring diagram?
Best you don't power it before you know which wire does what.
Usually, one wire feeds power in while the others feed power out to whatever's downstream of it when the switch is snapped to the appropriate position.
Set your meter to it's lowest Ohms setting.
Touch the meter's probes together to see it's base reading. That's what a switched connection should read, or close to it
Pick a wire and hold a probe on it, stay with that one and touch the other probe on each of the other wires in turn with the switch snapped to each of it's positions. You should see either an open circuit or a full connection. Write down all the results, from which you should be able to deduce what the wires do.

 

[GeorgeOC]

Hi George,
if you don't have a circuit powered up, use the lowest Ohms (resistance) setting to check that circuit's continuity.
If a circuit IS powered use the 20VDC setting to see where the power is going.
Of course, if the circuit is powered and it's bulb lights up and goes out when the switch is flipped that circuit don't need no steenkin' multi-meter.

George, each switch will have a feed to the switch and a send to a device. For example, the turn signals. You'll see a Br/W wire going to that. When switched to Left, the switch is making contact between the Br/W and Ch wires. That's your two ends. Br/W to the switch, the switch makes the connection, Ch out of the switch. Touch one lead to Br/W, the other to Ch. Switched to the Right, you'll see continuity between Br/W and Dg.

Right - DB has certainly outlined the process very well George.

The other key is to use the wiring diagrams and focus closely on the schematics of the switches. You should be able to follow a given wire from the headlight bucket and see what other wire it connects to when you move a given switch. Then you connect one of the leads from the meter to the first wire and the other lead to the second wire - and push the switch.

If the needle on an analogue meter swings to zero ohms (or the number drops to zero on a digital meter) when you push the switch - you've got a continuous circuit.

The beauty of this type of testing is that you really cannot damage anything because the only power in the circuit is that provided by the little battery in the meter itself.

+1 on the diagram.

Also, I usually turn the beep off on my meter because it's kind of annoying and the tests I've doing recently need actual resistance readings. The tests you are doing are binary; continuity or no continuity. I'd use the beep here.

Hi George,
If the switch is connected to the bike's battery use the Volts setting to look for power.
From what you say, I suppose you have a replacement switch with wires coming out of it (surely more than ONE wire?) that are colored differently that those in your wiring diagram?
Best you don't power it before you know which wire does what.
Usually, one wire feeds power in while the others feed power out to whatever's downstream of it when the switch is snapped to the appropriate position.
Set your meter to it's lowest Ohms setting.
Touch the meter's probes together to see it's base reading. That's what a switched connection should read, or close to it
Pick a wire and hold a probe on it, stay with that one and touch the other probe on each of the other wires in turn with the switch snapped to each of it's positions. You should see either an open circuit or a full connection. Write down all the results, from which you should be able to deduce what the wires do.

Gents, tremendous thanks. This was the ah-ha moment. Makes sense now! Will report back on the progress. Thank you all!

 

[mrtwowheel]

What multi-meter are you using? I still learn new things from the little books that came with mine.

 

[CoconutPete]

My multi-meter has a setting for just testing connectivity. That's what I use when I test switches.

 

[gggGary]

once you know the +12 lead AND the Ground lead then a light bulb tester is very handy. A meter can show 12 volts even through a path that is not capable of delivering any amperage.
there is a lot going on in that LH bundle, several different ins and outs. Any aftermarket unit should have come with a wiring diagram.

 

[GeorgeOC]

What multi-meter are you using? I still learn new things from the little books that came with mine.

Thanks mrtwowheel, I am using a Fluke 110. After reading the manual up and down there doesn't seem to be a straight forward connectivity function.

 

[mrtwowheel]

Thanks mrtwowheel, I am using a Fluke 110. After reading the manual up and down there doesn't seem to be a straight forward connectivity function.

It's got to be there in the book, measuring OHMs on the OHMs function of your meter.

Scott

 

[GeorgeOC]

Ohms, yes for sure then.

 

[Highwaystar]

once you know the +12 lead AND the Ground lead then a light bulb tester is very handy. A meter can show 12 volts even through a path that is not capable of delivering any amperage.
there is a lot going on in that LH bundle, several different ins and outs. Any aftermarket unit should have come with a wiring diagram.

on that I was in the switches and was getting 13.5 on the meter and yet nothing on the test bulb pretty sure that the flasher relay is just shot and as soon as any load is applied it dumps

 

[DanielBlack]

Original flasher? Those need a good 12v+ and the correct wattage draw. Stock on my bike was two 27w bulbs plus the 3w dash indicator per side.

A lot of us here are running electronic flashers available for a few bucks at the local auto supply store. They'll work below 12v, important for sitting at the light waiting to make your left turn, and if one of the 27w bulbs die.

 

[gggGary]

Original flasher? Those need a good 12v+ and the correct wattage draw. Stock on my bike was two 27w bulbs plus the 3w dash indicator per side.

A lot of us here are running electronic flashers available for a few bucks at the local auto supply store. They'll work below 12v, important for sitting at the light waiting to make your left turn, and if one of the 27w bulbs die.

True dat. but flasher default is always on, not that I have ever had a bike with turn signals that come on and don't flash unless the motor is revved, if then.