That Diode

[Joolstacho]

Do all GS500 models have that little 3-pin double diode?
Mine doesn't test out and I need to get another.
-Jools

[codajastal]

What is this diode you speak of?


Sent from my iPad using a big stick

[adidasguy]

Yes, they do.
It is the dual-diode that controls the side stand relay. Bikes must be in neutral or side stand up otherwise the side stand relay kills the bike.
actually, the dual diode isolates the neutral light from the side stand switch as the neutral switch and the side stand switch both turn on the relay to let the bike run.
Without the dual diode, the neutral light would come on when the side stand is up.

Surprised you dug in that far. That dual diode is buried in the wiring harness and vary hard to locate.

Any symptoms that made you go after it? How are you testing it?

[Joolstacho]

Adidasguy: Well i'ts a long(ish) story! Suffice to say that I'm working from scratch to ensure everything is right with the starting circuit. The suss little lad who sold me the bike told me he'd "lost the ignition key" - Har, har... heard that one before eh?
Anyway, when I got it home it turns out that the camchain tensioner was so rooted that the camchain had skipped teeth on the camshafts resulting in a valve hitting the piston when turned over (by hand). I'm hoping it wasn't run like that 'cos if he has there'll be a bent valve in there. So I've lifted the cams and retimed it, and fitted a new tensioner. I'll do a compression test to see if I have a bent valve.
The diode tests: no continuity between any of the 3 terminals, so I'm assuming it's stuffed?
Maybe I could bypass it? I wondered whether the later models have the same diode, if so it'll be easy to get a new one.

-Cheers,
Jools

[adidasguy]

They use te same diode. Are you are that the diode is polarity sensitive?
Diodes conduct electricity in one direction. They may have as high as 5k ohms resistance.
Set the meter to a higher scale - such as 1k or 20k and check each pair of leads with the probes in both directions.

[Joolstacho]

Interesting... no continuity in diode contacts in the 20k ohms range, but I did get 'transient' readings in 2000k and 200k ranges. So, after cleaning up the contacts I plugged 'er in and the starter turned over... job done eh! (FLW) 
-Jools

[adidasguy]

Ah, the old corroded contacts problem.