Neutral light

When my 2001 (with 140K mi) ST11 is first started and cool the neutral indicator light functions properly, but when bike reaches full operating temperature the light will not work and the bike will not start in neutral without pulling in the clutch, and the bike dies when the side stand is put down while the bike is in neutral. Bad neutral safety switch?? Where is the switch and how hard is it to replace?

Ya, it sounds like you have a funky neutral switch. It's located on the rear case. I couldn't find any more info than that in my service manual. You may have to remove the fuel tank to get at it. Pull the left ( right ? ) side cover, you may be able to see it - it has a single wire going to it.

Check out this PARTS DIAGRAM :
http://www.partzilla.com/parts/search/Honda/Motorcycle/1998/ST1100+AC/REAR+CASE/parts.html

I'm sure Uncle Phil , John O. or someone else can give you more specific info.

The location according to the service manual looks like it would be directly below where the fuel filler door is located, but way down low, so you'll very likely need to remove the fuel tank unless there's a way to get in there from the side. No remove/replace instructions in the manual, so hopefully someone who has done the job before can give advice. The manual does specify a torque value of 9 ft-lb or 12 N-m and to apply sealant to the threads.

Removing the tank isn't that big a deal, so even if that's the only way in, its not a lot of work.

dwalby said:

Removing the tank isn't that big a deal, so even if that's the only way in, its not a lot of work.

Click to expand...

Just make sure it's near empty!

And don't forget to disconnect the float connector on the left hand side of the tank before you remove it. [ Don't ask me why that's important. ]

Another possibility is a bad clutch diode. Check out this linky. A single green wire comes up from the neutral switch to the clutch diode. You can check to see if the neutral switch is good (without pulling the fuel tank) by connecting a multimeter to this wire and a ground point, and seeing if you have continuity when the bike is in neutral. If the switch grounds out in neutral then it is probably a bad diode.

The neutral switch is right next to the alternator and has a green wire going to it with a bullet connector. More than likely the connector at switch will be corroded. Easy enough to get at with the fuel tank out, to clean up the connection and test the switch. With what you are describing, it's one of three things. The connection, neutral switch, or clutch diode....

I am attaching two pix of the location...

Pics with annotation totally ROCK!

Thanks guys, I too have a manual, but it is not very helpful for this situation. I am a bit of gear head but I may pay for this repair. The bike is ride-able, just pull in the clutch. If I choose to tackle the further diagnosis and or repair, I may need more expertise.

Thanks

If you are a bit of a gearhead, then don't waste money at a shop. The fuel tank is very easy to remove, when near empty - four bolts (IIRC), wiring on top, a wire connector on the left side and the fuel hose and it lifts right out. Then you can easily see that neutral switch.

First off, why pull the fuel tank as the first step to diagnose the problem? The clutch diode is accessible by removing the L/R side covers and the top shelter, and is the small square package that is taped to the harness on the top left frame rail next to the throttle cables. Disconnect the diode package and test it with a multimeter.

It just doesn't seem logical to pull the fuel tank without first testing the clutch diode, it could save you a lot of work.

The symptoms fit a bad neutral switch exactly. I doubt the diode is bad. But you are correct, why not check the diode first ? But my money is on the neutral switch.

I attached a schematic of the neutral and clutch starting circuit for future reference. The low side of the starter relay connects to ground either through the neutral switch or the side stand switch (when the stand is up). The negative ends of the two diodes connect to ground through the neutral switch.

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I know this is an old post, but for anyone (like me) finding it on a search, as mcthorogood has posted a drawing of the starting circuit, as well as checking the diodes why not just check for continuity between the green wire and earth when in neutral. If it is s/c in neutral and o/c in gear then this proves the switch is OK. Also, earthing the green connection on the diode pack with ignition on will also prove the neutral lamp