Side Stand Switch Safety Circuit

I came to a realization about the side stand safety circuit on my 750 seca and turbo seca and wanted to share with the forum.

Contrary to what's been posted many times on the forum (unless of course the safety circuit is wired differently on different models) the side stand safety circuit DOES NOT cut off ignition if the clutch is let out and the bike is in first gear when the side stand is down. Some other bikes may do this, but I know that my 1982 XJ750RJ Seca and 1982 XJ650LJ Turbo Seca do not.

Looking closely at the wiring diagram, the side stand safety circuit is wired into the starting circuit (i.e. completing the low current circuit that engages the starter solenoid). I believe this means that the side stand safety circuit is ONLY meant to protect a rider from leaving the bike in first, then starting it and causing it to jump off the side stand. However, once started, if the owner puts the side stand down, then puts it into first gear and takes off, the bike won't stop you.

This also means that the side stand circuit cannot cause intermittent ignition problems.

Besides looking at an electrical schematic, this is very easy to test. Simply put the bike up on the center stand, start the engine, put the side stand down and put the bike into gear. The engine will continue to run.

I haven't altered my safety circuits in any way, although I should probably test to make sure that the 750 seca stand stand safety circuit is functioning properly won't start with the side stand down.

As for the Turbo Seca, I know it won't start with the side stand down. When testing it, I actually left the side stand down, while the bike was in gear, and on the center stand. The starter didn't spin, however, the fuel pump did. So if you own a Turbo Seca, and you need to spin the fuel pump to fill you carb bowls before starting it, just put it on the center stand, put the bike in gear and the side stand down, and push the start button. You'll fill the bowls right up without turning over the engine (and don't have to used the fuel relay bypass under the left front fairing).

 

Re: Info: Side Stand Switch Safety Circuit

Not so on most of the bikes; there should be a lead to the TCI from the RELAY (not the switch) that drops it to ground.

I can't speak to the 750 Seca with its myriad of warning lights; but on my 550 Secas, if the bike is running and I drop it in gear with the sidestand down, the motor immediately shuts off. (Then my smartass kid on the back yells "sidestand!") Clutch being pulled DOESN'T matter, if the stand is down and the bike goes into gear it shuts off. If the stand is up, then you can start the bike in gear provided the clutch is pulled in.

But yes, the safety circuits are different on different models, some have a "sidestand relay" separate from the cutoff relay and some don't. But the functionailty should be similar. Maybe you've got a malfunction in yours somewhere.

 

Re: Info: Side Stand Switch Safety Circuit

The side stand circuit is to prevent riding with the stand down. The relay disables the ignition, the starter cut out is to keep you from running the battery dead trying to start it with the ignition disabled.

Generally if a Yamaha (with side stand circuit) will run in gear with the stand down either the relay is defective or missing.

 

I've changed the title then. Something must be wrong with my bike's relays (both of them?). I haven't disabled or bypassed any of the relays intentionally, and I've been through both harnesses entirely.

So a missing relay (ignition) will allow the bike to run, or does it need to be bypassed (or stuck internally)?

 

You have a defect somewhere. I have a Seca 750, and when in gear, lowering the sidestand kills the engine (both clutch in, and clutch out).

 

I'm about to leave the house so don't have time to dig through the wiring diagram right now, but here is what I think:

All the XJs with side stand circuit are functionally the same, and the other Yamaha's from that era too.

You have two safety circuits. The safety relay makes sure the starter won't crank with the motorcycle in gear unless the clutch is pulled.

The side stand relay watches the neutral switch and side stand switch. If the side stand is down and the neutral switch is open the relay closes and kills the TCI. The side stand switch is also wired into the clutch safety circuit to keep the starter from cranking with the side stand down and the motorcycle in gear.

Since the side stand relay works by essentially shorting the TCI any open in the circuit (broken wire, bad connection, missing relay etc.) will disable the ignition kill function. Of course a bad neutral switch will also render it inoperative. Your neutral light does go off in gear?

My 89 Venture has a box similar to the Atari on your Seca. It has essentially two switches in the side stand switch assembly. One disables the ignition and the other turns on the side stand idiot light.

 

Well I feel dumb for being sooo certain that my bike was right and everything else that I had read was wrong. I feel bad for posting, but I guess it might save me if I ever lay down my Turbo Seca.

I've never suspected an issue before because all of the lights and warnings work, neutral light and side-stand warning included. The clutch safety relay works (won't turn over with clutch out, in gear, and side stand down). So I guess that points to either the starting circuit relay or a wire that would ground the TCI.

Furthermore, I really need to test if the emergency cut-off switch (tip-over switch) will kill the engine on the Turbo Seca in the event of a tip over. It would be a bad day if I lay that bike down, the switch grounds (I've tested the switch itself) but it's routed through the same circuit that's failing me now and I get a nice big puddle of gasoline thanks to the fuel pump.

 

Don't feel dumb at all. You brought up an important point (the proper functionality of the safety circuit) And in the process discovered something that could keep you from getting hurt.

Now you know what to look for thanks to Carl.

Something to keep in mind about the clutch switch: it ONLY allows starting in gear with the stand up. It's the "stalled it in traffic and can't find neutral" preventer. Once the sidestand comes down, the bike dies, period. The clutch switch will not (or shouldn't anyway) have any effect at that point.

 

Ok, finally got around to troubleshooting this. I actually hadn't ridden either bike much (I bicycle a lot to work) but I was also having some other electrical gremlins in my charging system.

For BOTH bikes, the lone plug off of the TCI which allows the multitude of safety interlocks to ground the ignition...was un-plugged. Mind you, I can't blame this on any POs, I've been through all of the harnesses myself . Oh well, at least I'm consistent :roll: . Now with either bike running, side-stand down, and clutch in, I put it in first and the ignition dies immediately.

I also found the red pin off of the RR connector un-seated from the connector (likely the cause of my charging system issue on the 750 seca). Which was something else that I fixed recently. Man I just can't win...