So, I finally got the tuneecu to run and the fault that keeps reappearing is the po335 crankshaft position sensor. Does this fault often because I don't know why it would have failed? Does anybody have any pics of its location? I'm gonna surf the repair manual and see what I can find but this fault is making less and less sense as the day goes by. It actually won't even start now ( it used to) but it could be because it's a little cold outside (KTM's) are complete bitches in the fall and winter).

Thanks in advance to anybody who replies.

All in the manual but check connector/wiring before you start taking apart to replace .

I'm 99% sure the crank position sensor is inside the engine cover clutch side. You can see the wires coming out of the engine where the clutch side cover joins the main engine cases towards the front. It wouldn't be a difficult job to swap it. Check the connectors first though.

I would check the connector on the front first. The sensor rarely fails.
The connector is in front of the engine just above the battery box under the radiator where the regulator is. It gets sprayed in water and crap from the front wheel.

absolutely correct, I checked the connector first. There was a light brown residue (probably oil) but I cleaned it out. Tried to start the bike again (good prime, gas is good) and still nothing. I have it on the lift, put it in first, tried to start it and I know at least the starter is good. The engine is cranking over and the chain and tyre move.

Just for grins and giggles, I disconnected the plug and tried to start it and sure enough, it did the exact same thing. I'm going to grab a multimeter from work and measure out the resistance for the plug. Since it acts like a switch, with it depressed in, it should short across the terminals. the other part of the plug appears to head up to the ECU.

I have pulled the ECU out and checked its status yet but the fact that the TUNEECU can talk to it, clear codes and respond kinda shows its working as well, but maybe not at 100%.

I won't be able to pull the casing apart until this weekend so stay tuned chummers.

Colonel Klinck, thanks for the pick and as always, thanks ktmguy.

If you ever get to come out to Japan, I'll be you a chu hai.

never mind about the depressing of the switch, I just realised its inductive. maybe a magnet?

Be very careful removing the engine case. You may be lucky and the gasket won't tear. If it does you'll need another. They aren't super expensive though.

if I can measure the resistance without having to remove the cover plate then I will try that first. I think I have a working simpson 260 somewhere (the perks of working in the military). I don't WANT to have to remove the cover plate if I don't have to. And I'll also check for the wire rot, but on initial inspection, it looked pretty good. No burns or charring from accidentally rubbing against the exhaust.

again, it will probably be this weekend until I get to mess with it again. It gets dark here at about 5PM and thats normally what time we get home.

Well ktmguy, if you're readings are correct (and I have absolutely no reason to doubt) it looks like I might have the first bad PG ever. With the plug disconnected, ohm meter set to read ohms, and meter leads tested, I got OL when reading between the two pins for the plug (yes, the ones for the actual PG, and not the ones going to the damn ECU). So, looks like that's the problem. with the plug still disconnected, I tried to read the voltage to see if it would flash while cranking and nothing. I'll get it on order and a new gasket today. Should be here in about 2 weeks (dammit).

yeah, I'm an electrician by trade and an open is usually a pretty good indicator that its broke as hell. just ordered the parts, they should be here in about 2 weeks.

Stay tuned!

What I would do in the mean time is pull the cover off and have a look inside, just for peace of mind.
Imagine you get the parts in and you open it up and come to the conclusion you need something else... it will ruin your day....

The oil in these engines lives in the tank so if you tilt it over nothing comes out the sump anyway. Like Klinck mentioned be careful with the gasket and you might be able to put the cover back on till the parts arrive.

I used to hang it from a ratchet sling on the frame from a solid roof mount or so and tilt it on it's side.

To be on the safe side, I purchased a gasket, which, when I pulled off the cover, there would have been no way to salvage.

PG looked fine except there was a minor scratch on the top. It "could" have come in contact with the cog but I seriously doubt it. The screws holding the PG in place were torqued on like a titans nuts. I installed the new PG, and ensured enough clearance so it wouldn't touch, but kept it close enough to relay the magnetic pulse from the gear.

Put it all back together (minus all the damn anti-freeze that leaked everywhere) and started her up.

TUNEECU came back with no faults and the bike rode like the crappy dream it is.

I downloaded a map from the TUNEECU site but I don't know exactly how to load it, or even to read the map that is currently on there.

I'll have to peruse the TUNEECU thread.

Thanks again everybody for the help. The pig is now running again.