[Davydo]

Here ya go NMK...

[NMKawierider]

Here ya go NMK...

I'll be damned..I'm shocked. That shouldn't have made any difference but clearly the base isn't grounding well...or for some reason current isn't making it from the base to that main battery ground cable.

[Ponytail]

Broken ground somewhere along the ground wire???

[Davydo]

The sensor body itself is ground as it makes contact to the housing it screws into according to the service manual info.  The only other disconnect I can fathom is where the thermostat housing, which the sensor screws into, mounts down on the cylinder head. Theres an o-ring to seal up and not a gasket, so the casting mating surfaces might have some corrosion build up or need to be cleaned resulting in a lost ground down the cylinder body. Also, I bench tested the sensors in a pot of water over the stove to duplicate the heating process. I had my ohm meter connected to the body and the B-pin the water temp reached 122 degrees, 176 degrees, and 212 degrees the resistance readings were way too high on all three sensors according to the service manual information. I dont know if that would interfere with the sensors ability to ground?? Anyhow, at the end of the matter, when Cfmoto decides if they have a problem or not with these sensors and if disassembling the thermostat housing and cleaning the mating surfaces with a scotch brite pad to remove corrosion doesn't fix the problem, I'm gonna solder a wire to the sensor body and connect to the ground bolt in the picture like Murdo suggested and hopefully move on with life.

[Z8rider]

resistance of the sensor increases as the temp goes up, if your bench test showed high, then the display would still show some type of reading versus nothing. In theory the reading would show high on the dash display

[Davydo]

Out of service manual and my resistance readings on the first and second replacement sensor.

[Z8rider]

either way, you're over-thinking it, the resistance values at a given temp are somewhat arbitrary in your case. Even if they are out of spec, with your values, you would still see something displayed on the dash. I think I gave the resolution (as you mentioned) to this a long time ago. Get the sensor a good path to ground, i'd save your time and just do a secondary ground.

[doug80638]

None of this makes sense to me. Need to step back a re-evaluate.

You've cleaned contacts and made it work for a while with two different sensors. This tells me it isn't the sensor.

I would first suspect an intermittent/poor  connection someplace in the wiring, including a possible break inside the insulated wire that makes contact when you move the wire (like when you are cleaning contacts).

All this talk of a separate ground for the sensor is silly to me. Check the continuity between the sensor and the block before attempting such a questionable band-aid. I'll bet it is just fine. If not, remove some of the thread lock and reinstall until good contact is achieved.

As for the sensor, are their any identifying markings or part numbers on the original sensor? On the subsequent replacement sensors?

[Z8rider]

what sounds silly to me is how long this has been going on when the owner knows what the issue is that I have called out multiple times.

questionable? you are providing a secondary ground to what the sensor does in the first place, basically a fail-safe layer. Do it and move on...

[doug80638]

Yes questionable.

The secondary ground is a band-aid which does not address the real problem, a problem that could possibly affect other systems if left uncorrected. And it should be a simple matter to diagnose.

You need good continuity from the sensor to the block and good continuity from block to ground. Both easily tested.  If you have those two things, then you don't need a questionable band-aid and need to look elsewhere for the problem (like wiring).

Fix it right the first time.

[Z8rider]

Yes questionable.

The secondary ground is a band-aid which does not address the real problem, a problem that could possibly affect other systems if left uncorrected. And it should be a simple matter to diagnose.

You need good continuity from the sensor to the block and good continuity from block to ground. Both easily tested.  If you have those two things, then you don't need a questionable band-aid and need to look elsewhere for the problem (like wiring).

Fix it right the first time.

nothing in the wire-harness affects the sensor to ground relationship. Secondary ground affects nothing else with the vehicle, it simply satisfies what the system inherently is not very well at doing. No different than any of the other "improvements" people swear by. You guys can go around and around with this all you want. Good luck!

[Davydo]

Thank you gentlemen for your comments.

[Davydo]

 I tested continuity between the sensor body and the the thermostat housing and it's there, then I slid my contact down past where the housing bolts down to the cylinder head and lost continuity amd repeated several times. So my problem like everyone suggested was loss of ground I'd imagine all this time even though the sensors bench tests were not in the manuals rated resistance. I'll disassemble the thermostat housing and scotch brite the mating surfaces. Hopefully itll fix it finally.

[Ponytail]

I’m no electrician but..... that plug 🔌 has 2 wires. One is hot one is ground. When you jump over that ground it works. I thank either the ground is broken somewhere in that wire or the plug is bad. JMO...

[NMKawierider]

If there is one thing I have learned working with these Chinese machines is-"Expect the Unexpected". Things you wouldn't think could or would happen on any other maker.. is more then possible with these.