Head scratching wiring problem!!

I have just fitted a complete perfect conditon wiring harness to one of my st1100's and everything is working perfectly apart from the dammed neutral warning lamp!! an explanation follows ...

Neutral lamp works normally with the engine not running.

Side stand down, clutch in engine won't turn over (neutral lamp on)

Side stand up, clutch in engine turns over and starts (neutral lamp on)

Clutch in, put into gear (neutral lamp stays on but dulls very slightly)

Release the clutch in gear (neutral lamp goes off) but every time I pull the clutch in to change gear the neutral lamp comes on working off the clutch switch!!!!

I have tried bypassing the side stand switch but makes no difference to the neutral lamp just stops the engine turning over, anyone had the same sort of problem (the harness was identical to the one removed) is there a relay that could cause this fault because I used all relays that came with the harness off a donor bike untested) .... if so wich one is it cos they all look the same!

I would be suspicious of the clutch switch. On one of my ST1100s, the bike will sometimes not start when the neutral light is on unless I pull in the clutch. I can't remember if the clutch switch is a naturally 'opened' or 'closed' switch, but I'd bypass it and see what happens.

Clutch diode? It's the lump inside the wiring loom running between the upper frame tube and the left side of the air cleaner housing. Picture available if asked.

John

Thanks folks, I shall be changing the clutch diode tomorrow and will let you know how it goes.

You can make one cheap with two diodes for a fraction of the cost of the OEM part. There's instructions somewhere in the tech forum. The OEM costs $26 here in Canada Can you slavage the one from the old harness?

I will be using one from the old harness which I know didn't have the fault, so fingers crossed.

Dinosaurbuilder said:

Clutch in, put into gear (neutral lamp stays on but dulls very slightly)
Release the clutch in gear (neutral lamp goes off) but every time I pull the clutch in to change gear the neutral lamp comes on working off the clutch switch!!!!

Click to expand...

hmm... I'd the very same symptoms on my prev '92... turned out to be a dodgy neutral switch...
However, swapping the diode for a cross-check is an easy thing, if the trouble remains, dig for the neutral switch...

Thanks folks, all sorted, it was the clutch diode now all systems working perfectly and another 1990 st1100 with 50K on the clock back on the road, maybe it will get run in someday. Thanks again it's good thing to have a live data base.