Help reading 78 GL1000 color schematic

[pidjones]

I bought a couple from an eBay vendor who has a bunch of used ones - they were both good.

[EdK]

Do you have a link by any chance?

[Sidecar Bob]

It is best to use the ohms scale instead of the continuity test setting whenever possible. In this case yo should use the lowest HIGHEST range and you should read a very high resistance with the leads connected to the diode one way and a low resistance when you reverse the leads.

EDIT: You need to use the highest ohms scale, not the lowest.

[EdK]

Thanks,
I'm getting nothing either way. I guess all of mine are shot. Hopefully the ones I ordered on ebay work!

[pidjones]

Do you have a link by any chance?

https://www.ebay.com/itm/Honda-75-79-GL ... 2749.l2649

[Sidecar Bob]

I just realized that I gave you the wrong information in post #18: You need to use the highest ohms scale to test diodes, not the lowest. I have corrected this above.

[EdK]

Thanks, I did get a reading on the highest setting (20M) Here's the 4:

10.9 1.07
5.46 2.30
4.71 1.34
5.47 -----

These are approximate because I get a different reading every time I test them, and it seems to fluctuate.

Thanks

[Sidecar Bob]

Make sure your fingers are not touching the test probes or the terminals on the diodes while you are testing. The human body, being mostly water, conducts enough that the electrical resistance of the skin can be measured; Some meters will only do this of the probes touch the skin close together (like half an inch apart on the same finger) but others sill provide a reading when you hold one probe in each hand.

Also, make sure the terminals on the diodes are shiny clean where the test probes touch them because your meter actually measures resistance by passing a very small current through the item being measured and dirt/oxidization on the metal can affect the amount of current that flows and cause false readings.

[EdK]

Thanks, sorry for being so remedial about this - I cleaned everything up a little more and just probed on the bottom edges of leads.

All came out to around 5.0-6.0 on one side and nothing on the other.

[Sidecar Bob]

If you mean "nothing" as in the same as when the test probes aren't touching anything with the leads connected one way and 5-6 ohms with the probes reversed then I think your diodes are OK.

If you mean "nothing" as in zero ohms, the same as with the test probes touching each other that is a different matter altogether.

BTW: If you are unfamiliar with using meters for electrical/electronic measurement I highly recommend reading https://electronicsclub.info/meters.htm and then https://electronicsclub.info/multimeters.htm

[EdK]

Yes, that's what I mean - same as when the probes aren't touching anything. Thanks for your help, and for the references. Wish me luck, by this weekend I'll have the new harness in hopefully back on the road. I'm learning a lot about these bikes that's for sure. Fingers crossed!

[desertrefugee]

Body resistance should not affect a resistance measurement unless you’re in a high (Mohm) range. Even soaking wet, you’d probably read a couple of kohms unless the leads were literally millimeters apart.

[Sidecar Bob]

As I said in an earlier post you need to use the highest resistance scale your meter has when testing diodes.

We were taught not to let your fingers touch the test probes when measuring high resistances (like the reverse of a diode) when I was in school and the reasons why haven't changed in the 4.5 decades since. My good analog 100,000 Ω/volt meter is still my more accurate than any of the digital ones I have (not to mention that there are some things a digital meter just doesn't do well). If I set it to the MΩ scale and grab one lead with each hand it reads about 2-3 MΩ.

[CYBORG]

I agree with everything Sidecar Bob said, as that was the same wisdom I gleamed from the USAF, and MIT

[EdK]

Just want to follow up and say thanks to everybody for all the help.

My problem started here: https://www.ngwclub.com/forum/viewtopic.php?f=1&t=65624

As of today I got the new harness in, and lo and behold she started up and just about everything worked! I spent a lot of time going over the new (used) harness before I installed it, and I also installed a new main fuse. As I went through I checked and cleaned all connections, and made repairs where needed. There were quite a lot of bad connections, especially behind the headlight. I wouldn't wish this on anyone, but on the plus side I now have a way better understanding of my bike's electrical system than I would have otherwise. Getting pretty good at reading a schematic too.

The only issue I can see right now is my front turn signals aren't working. And I can hear the flasher working all the time. Still and all very happy with the way everything went.

Cheers!