ITS voltage check

[Drrhein]

Having looked at the Schematic for the sensor I can see how I might be getting the strange Ohmmeter readings. If the Rectifier bridge is merely made up of four diodes and they're wet, then it's possible I'm seeing the Capacitor.

The two attached pics show two sensors, one is old but works, one is old and doesn't. One was sitting in water. You can see where the nut corroded and flowed corrosion into the crack in the potting. Both sensors appear to be cracked in about the same places, interesting.

I'm probably going to silicone the cracks on the good one and use it.

I also have a scope and frequency counter so If I have time I'll scope the inputs on a good cart and try to take pics. I'll also get the frequency and see what happens as the slug goes in. Then I'll have a baseline to publish here if anyone is interested.

Should I start a new thread when I get that info?

[radioman]

I would post it here. I looked at the ITS output on a scope once and all I could see was a DC voltage with some high frequency hash riding on it.

[JohnnieB]

Originally Posted by Drrhein

..............
I also have a scope and frequency counter so If I have time I'll scope the inputs on a good cart and try to take pics. I'll also get the frequency and see what happens as the slug goes in. Then I'll have a baseline to publish here if anyone is interested.

Should I start a new thread when I get that info?

The ITS sensor is only 1/3 of the ITS circuit. The other two parts are in the controller. Those being the power source for the sensor and the demodulator that converts the variations in DC current flowing through the ITS sensor into the specific throttle signal used by the specific controller.

The voltage across and the current through the ITS sensor, are dictated by the controller, so those parameters vary by the make and model controller the ITS sensor is connected to.

The operating frequency is approximately 16kHz and does not vary when the slug is inserted into the sensor coil. The two terminals on the ITS sensor are fairly well isolated from the oscillator and coil drivers by filter capacitors, so you probably won't see much more than straight-line DC on a scope. However, the controller's PWM operates in the same frequency range, so you may pick up some EMI from the controller.

The thing to remember is that the ITS sensor is a current device, rather than a voltage device.

Good luck with your testing.

[Drrhein]

The rebuilt controller came in so I installed that without changing the ITS sensor. The voltage at the sensor was still .9 to 2 volts and the motor speed at pedal switch contact was too high. Changed the sensor with the old one mentioned above and the voltage came down to .45 to 1.5 and the speed is correct now. It seems to me that if there is too much current flowing through the solenoid and controller when the pedal switch breaks that there might be a big arc across the contacts and that can't be good for the controller either.

The scope readings were as mentioned, mostly DC so not worth taking a pic of and nothing registered on the frequency counter.

It's clear though, The cracks in the sensor potting must let in moisture and cause major problems.

I can't help but wonder if the cart was flooded at some point. The pedal box had more water in it than can be explained by just minor leakage. There is more corrosion on the cart and especially the motor than would normally be seen on a cart of this vintage.

Anyway, everything's is working and I drive it back to the guy tomorrow.

A good education on the ITS system in this thread and in previous threads, thanks to all!

Dennis