Motor only runs with sensor harness unplugged?

[TheLetterJ]

I recently bought a new Hobbywing Xerun SCT Pro 120A ESC and 3656 4 pole 3400kv sensored motor. While trying to bench test it, it is unresponsive to throttle input other than the red light on the esc turning on when it gets throttle signal. I tried unplugging the sensor cable and then everything works as normal. I went through the throttle/esc calibration, battery is charged, phase wires are hooked up in the correct order, what am I missing?

[Prime]

Is it programmable? Does it have to be set to run in sensored configuration? I ask cause I am not familiar with that particular ESC but sounds like maybe a setting issue.

[JatoTheRipper]

Did you try a new sensor cable. Those things are fragile and die more often than they should.

[CM9000]

try reprograming it first, if that doesn't work you need a new sensor wire. tekin ones I find to seem be the best as far as quality goes. flexible and don't break at the plugs as easy.

[JatoTheRipper]

Originally Posted by CM9000

try reprograming it first, if that doesn't work you need a new sensor wire. tekin ones I find to seem be the best as far as quality goes. flexible and don't break at the plugs as easy.

Holmes has good sensor wires as well. Very flexible.

[TheLetterJ]

I tested for continuity on each of the 6 sensor wires and they all checked out good. I'll need a longer sensor harness to install this in my Wraith anyway, so no harm in ordering a new one.

If I "bump" the spur gear and hit the throttle while the spur is still in motion, I have throttle control all the way down to minimum rpm with no notable cogging (it does cog some with the sensor unplugged) and up to full thottle, but if I let it come to a stop, it won't restart with throttle alone.

The ESC is programable, but there is not a sensored/sensorless setting. I tried swapping the phase wires around even though the motor/esc are both clearly marked A B C, and it would not run even with a bump (it would run with the wires swapped and the sensor unplugged), so I am pretty certain that is not the issue.

I don't own any other sensored setups so I can't swap parts around for testing purposes. Any other suggestions on what I should check?

[JatoTheRipper]

Originally Posted by TheLetterJ

I tested for continuity on each of the 6 sensor wires and they all checked out good. I'll need a longer sensor harness to install this in my Wraith anyway, so no harm in ordering a new one.

If I "bump" the spur gear and hit the throttle while the spur is still in motion, I have throttle control all the way down to minimum rpm with no notable cogging (it does cog some with the sensor unplugged) and up to full thottle, but if I let it come to a stop, it won't restart with throttle alone.

The ESC is programable, but there is not a sensored/sensorless setting. I tried swapping the phase wires around even though the motor/esc are both clearly marked A B C, and it would not run even with a bump (it would run with the wires swapped and the sensor unplugged), so I am pretty certain that is not the issue.

I don't own any other sensored setups so I can't swap parts around for testing purposes. Any other suggestions on what I should check?

Did you calibrate the ESC? Either your throttle range is incorrect or your sensor cable is bad. Or there's a dead spot on your motor. I can't think of anything else.

[TheLetterJ]

Yes, I calibrated the throttle range. I even tried a different rx/tx and recalibrated, no dice. The motor/esc are brand new, so hopefully one of them isn't just bad since I'm pretty sure there is no warranty once I've soldered them up. I'm might open up the end of the motor to look for any obvious problems with the sensor, but I'm honestly at a bit of a loss.

[JatoTheRipper]

Originally Posted by TheLetterJ

Yes, I calibrated the throttle range. I even tried a different rx/tx and recalibrated, no dice. The motor/esc are brand new, so hopefully one of them isn't just bad since I'm pretty sure there is no warranty once I've soldered them up. I'm might open up the end of the motor to look for any obvious problems with the sensor, but I'm honestly at a bit of a loss.

Wait for the sensor wire before you open the motor. Sensor wires cause many odd issues.

[TheLetterJ]

I really hope it's that simple!

[CM.gbg]

I have the same setup (Xerun SCT Pro + Xerun 3656 3400kv), except mine is used and suddenly I experience the exact same behavior as TheLetterJ. I apologize for digging up an old thread, but I would appreciate if you could please share how this was resolved and if you ever found the root cause.

I can add that I tried with a second motor of the same model and got the same result.

[TheLetterJ]

I never did find the root cause. After trying a new sensor harness, with no change, I gave up on running sensored since I didn't really need it in the Foff application it was being used in. I had been running 4s for awhile with no issues, but one day it decided to be way down on power and get REALLY hot, like hot enough to melt solder out, so I just gave up on the whole system... kept the fan and program cards since they'll work with my SC8 esc's.

I don't know if it was the motor or esc that was the problem, but I've got a feeling that one of them was just faulty right out of the package. I didn't want to damage a new motor or esc by pairing it with either of the old hobbywing parts, so I eventually replaced it with a Mamba X and 2700kv Holmes Puller Pro (after going back to brushed, then Mamba X with a 1800kv Revolver.)

Sorry that I don't have a better answer for you.

[CM.gbg]

Thank you for taking the time to answer. I'll do the same and run it unsensored until it finally gives up.

[CM9000]

Some speed controls need to be programmed to know if its a sensored motor or not. Might want to look into that. My DE10's were like that.