please help me understand f/r switch ohm readings

[rbridges]

https://www.buggiesgonewild.com/atta...5&d=1336743911

we had a f/r switch go bad last summer. I replaced it, and it's been fine since. My wife was out riding the other day, and it quit. She said it moved for 2 seconds and then stopped. The solenoid clicks. Pack voltage is 37v.

Using the diagram from here: https://www.buggiesgonewild.com/atta...5&d=1336743911

I tested resistance in the forward and reverse positions. In forward I get -0.4 ish with a solid tone if I have the red lead at #5 and black at #3. When I put red at #3 and black at #5, the screen goes blank and no tone. I know the negative means there's a load on it, but I'm not sure why I get a tone with the leads in one position and not another since it's measuring continuity. Normal readings at 4 and 8 with either polarity.

When I put it in reverse, I get good measurements at #3 and #8, but I get the same issue with 4 and 5; -0.4 with leads in one polarity and a blank screen when reversed.

Position #5 seems to be the common site with the weird readings. It's a cheap multimeter, and I couldn't find any info saying what the blank screen means. Since there is no tone, I'm assuming it's a loss of continuity with a certain polarity.

Does it sound like a bad f/r switch, or should I keep looking? Thanks!

edit--I disconnected the battery pack, and I still get the negative reading; -0.45 at 3-5 and 4-5. Why would I get a negative reading with no voltage going through the system?

[radioman]

I would like to help but I am completely confused about where to start. Resistance (Ohms) has no polarity. Select continuity on your multimeter and short the two test leads together. You should get a beep if the test leads are good (have continuity). Now place the leads across the switch terminals where you expect to have continuity per the instruction you posted. Anything less than a beep should indicate lack of continuity. If the circuit is open some ghost voltage readings may display on your meter.

[ThreeCW]

As radioman pointed out, there is no polarity with resistance ... it sounds more like a meter problem.

It might be as simple as you need to replace the battery in your multimeter. This has been noted on a number of BGW posts ... so you would not be the first person to get erroneous readings from a meter with a bad battery.

Failing that, perhaps borrow a meter and check the resistance readings again.

[rbridges]

Originally Posted by radioman

I would like to help but I am completely confused about where to start. Resistance (Ohms) has no polarity. Select continuity on your multimeter and short the two test leads together. You should get a beep if the test leads are good (have continuity). Now place the leads across the switch terminals where you expect to have continuity per the instruction you posted. Anything less than a beep should indicate lack of continuity. If the circuit is open some ghost voltage readings may display on your meter.

It works fine and you described when I just touch the leads together. I did some googling, and they said you can get polarity in the case of capacitors and such, but I don't know why in this situation. It has me stumped. I get a tone with the leads in one setup along with a small negative number (-0.45). When I swap the probes, I get no tone and the screen blanks. I have a nicer fluke meter, but it's out of town right now. I may wait until I get my hands back on it to see what it says.

[rbridges]

Originally Posted by ThreeCW

As radioman pointed out, there is no polarity with resistance ... it sounds more like a meter problem.

It might be as simple as you need to replace the battery in your multimeter. This has been noted on a number of BGW posts ... so you would not be the first person to get erroneous readings from a meter with a bad battery.

Failing that, perhaps borrow a meter and check the resistance readings again.

I just bought it yesterday and used the 9v battery that came with it. I'll try swapping it for a new one and see if it changes anything. Thanks!

[JohnnieB]

Originally Posted by rbridges

edit--I disconnected the battery pack, and I still get the negative reading; -0.45 at 3-5 and 4-5. Why would I get a negative reading with no voltage going through the system?

The controller has a dozen or more 1,000µF capacitors between its B- and B+ terminals, so there is a voltage source even when the battery pack is disconnected. The capacitors have a bleeder network, so the voltage bleeds off in about 5 or 10 minutes, or so.

[radioman]

Originally Posted by rbridges

I just bought it yesterday and used the 9v battery that came with it. I'll try swapping it for a new one and see if it changes anything. Thanks!

What your meter continuity test is trying to tell you is the switch contacts are not making. Regardless of voltage present in the area you should get a beep across the contact terminals if they are closed making contact just as you get when you short the meter leads together. I suspect the switch contacts are not making. May be due to improper alignment/adjustment, defective or damaged due to improper installation or some other unknown.

[rbridges]

Originally Posted by radioman

What your meter continuity test is trying to tell you is the switch contacts are not making. Regardless of voltage present in the area you should get a beep across the contact terminals if they are closed making contact just as you get when you short the meter leads together. I suspect the switch contacts are not making. May be due to improper alignment/adjustment, defective or damaged due to improper installation or some other unknown.

All that makes sense except I get a tone one way, and no tone when I switch the red/black probe.

[MacGyverr]

If your F/r switch is off alignment by just a small amount it will burn the contacts, causing resistance which your meter is showing you. As i posted just recently alignment is easily changed by not backing up the shaft when you install one.

[radioman]

Originally Posted by rbridges

All that makes sense except I get a tone one way, and no tone when I switch the red/black probe.

See post #6. The stray voltage is likely coming from the controller, and it is playing tricks on your meter readings. If the contacts were making you would get a continuity beep regardless of the how the red or black leads are connected because stray voltage would be bypassed by the closed contacts. You are getting false readings. Forget the readings and look for a beep. No beep = open contact.