As I stated above, the problem is very intermittent. It has actually done this to me 2 times , both during the same inspection. any other time I have tried to check it, it runs fine for me. When it does it on someone else, they put it in neutral and call me. when I put it in gear, it works. It has to not work to bypass anything. I was hoping some one else might have encountered this same problem and figured it out. As it is, for me to check anything, it would have to not work. I would only know if I bypassed something and it still had the problem that it was not that. I truly appreciate any and all suggestions. As for the neutral light goes, it only comes on when the truck is in neutral.
For a temporary test you can bypass the seat switch while you operate it and test it, but MAKE SURE YOU CONNECT IT BACK. This will rule out the seat switch and wiring completely. If it still causes travel issues, I am sure the Neutral light is coming on then the truck doesn't travel. I would suspect that the OSS controller is faulty. Make sure you order the correct part # also as there are many and the numbers are only 1 digit difference.
Back again, the forklift started working again on its own for a short time. Now it does it when it wants, usually when you need it the most. There is no trigger that I can find, and it only does it some times. It might go days without a problem, then have a problem every few minutes others. Just a few minutes ago, I went to check it because they were having problems every few minutes, and when I started to back it out, it stopped with a short alarm. I put it in neutral then back in reverse and it backed out fine. I put it in forward and drove it for about 200 - 300 yards and it did it again. I put it in neutral and back in forward, drove it for 20 minutes doing every thing I could think of that might trigger it, but it ran fine the whole time. I checked all the connections and the insulation on the wire and couldn't find any problems. as I stated before, this machine is only a couple of years old, and taken care of. physical appearance is excellent. I don't really know how to check the safety switches with it only having a problem sometime.
Sorry i should mention, also confirm your park brake switch works as well. Often a broken brake switch wire will cause this symptom.
Check seat switch and related wiring. Some models will move and operate for a few seconds if the seat switch fails then will sound alarm.