Throttle Position Sensor?

[cmayes]

I've got a 2002 Supra Launch (new to me this season). Boat runs fantastic, but every now and again the boat seems to think it's not in Neutral and disables the ignition and the boat won't start. Often times if you move the throttle in a full range of Forward & Reverse it generally does the trick and it fires right up - no issues. But last night my sister took the boat out and the throttle trick didn't want to work, she tried it a bunch with no luck. Eventually it must have worked and the boat fired up and all was well.

My question is - Is there a sensor that wears out and needs to be replaced? Are the contacts prone to coming loose? :confused:

Any help would be great!

[Cusefan78]

I would check the shift cable to make sure it's actually setting the tranny fully into neutral. If you're moving the shifter back and fourth that sound like the culprit. Tps sensor I don't believe has anything to do with that. Just tells the cpu where the throttle butterfly is

[cmayes]

Thanks Cusefan78 - can you give me a pointer on where to look for the cable location on the tranny? From working on cars I know that TPS sensor was the wrong term, but couldn't figure out what to call it, Shift cable sounds like it's probably the ticket. Is there a sensor of any kind at the shifter itself or all done at the tranny?

Thanks!

[Cusefan78]

I believe the sensor you where looking for is called the neutral safest switch. That is located on the tranny. First off. Remove the shift cable off the tranny. Check to see if the tranny is actually in nuetral by moving the shift lever on the tranny. You want to actually feel a click in the center location. When you're positive it's in nuetral go and try to start it. If it starts you need to adjust the lever. If it doesn't check the contacts on the nuetral safety switch. Clean them and reattach the wire. Try and start. If it doesn't still change out the switch with a new one. Can get them at skidm. If it still won't start your boat hates you.

[UKandH]

Correct, the TPS is just a feedback into the ECU to tell the system where the throttle position is. Its just a sanity check for the DFI.
TPS issues usually manifest themselves as erratic idle, misfires at certain throttle positions and jerky throttle response. they are usually caused by the track getting worn because of vibrations at the most common throttle settings (normally for marine engines this is approximately 3/4 open)

The system fault you are describing isnt a TPS issue as Cusefan has stated and most likely the Neutral switch

[cmayes]

Perfect - I'll take a look this week and get it sorted out. It's the Neutral switch for sure - boat idles and runs perfectly. Anybody have a picture of the switch/cable location on the tranny?

Thanks Guys!

[flipz96]

Perfect - I'll take a look this week and get it sorted out. It's the Neutral switch for sure - boat idles and runs perfectly. Anybody have a picture of the switch/cable location on the tranny?

Thanks Guys!

You should be able to see the neutral safety switch move when you move your throttle in gear. I don't have a picture on me right at this moment.