XS500 Strange electrical behavior

[650Skull]

@minus150

What year is this diagram for???............i read the 73/74/75 have the same loom and it changes in 76

Cant guarantee the wiring matches the bike. Did find a couple of the
wire lables were wrong. Haven't corrected them but the wire colour is the guide.

Do check the right bar switch wires for a L/W, (blue/white), wire. This comes from the L/R, (blue/red) going to the Brake lining warning switch wire. On the diagram the L/W comes off the L/R in the loom........

 

[minus150]

The wiring diagram is for a 1975 XS500B which matches the model of the bike. Wow the colored guide is fantastic, thanks for that. I picked at it a little more after work today and uncovered a splice hiding under some electrical (DG at harness). But according to the diagram it was done correctly other than the mismatched Br insulator color and feeds into the RH flasher circuit like it should. A little suspect but not sure if it factors into my problem.

Continuity on all RH bar switch wiring checks out including the L/W. The wire color differs from the diagram at the zener diode, but I believe my black goes to LR and my white/black goes to LW.

 

[650Skull]

Download the coloured diagram. I mucked up the B/R wire, have fixed and re posted the diagram

The wiring in your pics looks to be in good condition. A good wipe down with something like WD40 would make it look brand new. If the rest of the bike is like that it shouldn't be to hard to fix when you find the prob

Does the solenoid/Starter switch have L/R going to it??

 

[minus150]

No LR to starter solenoid, little more color inconsistency there. It's LW all the way from the bar starter switch.

 

[650Skull]

So we have L/R from the Brake lining switch on the rear hub, to the Brake lining light in the tack to the black wire at the diode, from the diode on W/B to L/W to the solenoid and Bar switch............Yes?

 

[minus150]

Yep I believe that to be correct. I do have a little resistance from the WB at diode to the LW at starter switch in the bars. 0.4 ohms

 

[650Skull]

Did you touch the probes to see if there was any resistance..........If there is that will show up when it should be reading infinity.

On the early Xs650's the earth wire is on the bottom of the through bolt that holds the Handle bar dampers. The earth from the bar switch is when it clamps to the bars.

The inside of you bar switch look pretty clean. Still wouldn't do any harm to dismantle all of the Switches, clean contacts, lube and reassemble.

 

[minus150]

Well I'm a little embarrassed it took me so long to find, but the oil pressure warning and brake lining lights were reversed at the dash. I still can't explain the brake light interfering with the flashers. But I'm going to charge up the battery and see if it's still an issue while running as others have mentioned it might not be. I found a source for dash bulbs here https://www.hondapartsnow.com/genuine/honda~bulb~dash~34902-259-000.html

@650Skull yes that value factors in the resistance value between the probes directly.

 

[650Skull]

Well I'm a little embarrassed it took me so long to find, but the oil pressure warning and brake lining lights were reversed at the dash. I still can't explain the brake light interfering with the flashers. But I'm going to charge up the battery and see if it's still an issue while running as others have mentioned it might not be. I found a source for dash bulbs here https://www.hondapartsnow.com/genuine/honda~bulb~dash~34902-259-000.html

@650Skull yes that value factors in the resistance value between the probes directly.

Redone the diagram to show the change at the diode............also resized it up a bit larger but the site has dowsized it but it is still a bit bigger than before. Id=f you want the larger version Pm me with an email and i will send o=it to you or you can resize it yourself.


Have the Dg and Ch Flasher wires been tested?? Do need a good battery or you could be chasing problems that arn't there

Also check where the wires go into the headlight bucket. Where the loom goes into the bucket can be a problem area especially when the rubber dampers deteriorate and fall out the bucket cuts into the loom creating shorts

 

[mrtwowheel]

Some of your earlier posts made me think of this.........keep in mind, while you are checking for continuity, that when a light bulb is in a circuit that circuit will show continuity between positive and negative. For a true continuity test in some situations remove light bulbs, and in some cases, disconnect electric motors.

Scott

 

[minus150]

Have the Dg and Ch Flasher wires been tested?? Do need a good battery or you could be chasing problems that arn't there

These wires tested ok, and the rubber grommet wire protectors in the headlight bucket are old but intact.

@mrtwowheel Good point, this initially confused me going through and testing.

The cause of the remaining problems (flashers not flashing, idle speed drop when stop light is illuminated) seem to have been caused by operating while not running the motor and using an undercharged battery. With the battery charged up and the motor running, the flashers don't have an issue. I edited the first post with findings. Thanks to all for troubleshooting, will be keeping that color coded wiring diagram handy.

 

[650Skull]

Good to hear and thanks for the reply on your solution to finish the thread