Weird upgrade issue

[CarterCrew]

Working on a friends '07 TXT(PDS). Diagnostics pointed to failed controller, so he ordered an XCT-48400-PDS from ScottyB (Awesome service,BTW!)

Replaced the controller last night, instructions are thorough. The comment in there about not being able to plug the cart harness in wrong is wrong (see pic #1).

Once installed, checked, corrected, and checked again, we powered it up, got the 4 green followed by 2 green-4 red error. I plugged in the laptop and checked the maintenance tab, it said the throttle was 100%, pressing it made it go down. We reversed the black & white wires at the ITS, after extending the white an inch, it works.

Anyway, here is the question: How is it working?

[scottyb]

Thanks for the heads up on the instructions. Keeping everything up to date is a never ending chore. The comment you were upset about is from the old model DCX control and has been revised.
I don't see any pics you referenced but, here is one of the ITS showing blk and wht wire locations.
Your wires could be reversed at either one of the 2 harness plugs ? Anyway glad it is running and hope your neighbor is enjoying the improved performance.

[JohnnieB]

Considering the fact that the input circuit of an ITS sensor is a full-wave bridge, I don't see how swapping the black and white wires at the ITS sensor (or anyplace else) changed anything electrically. (Attached is a block diagram as well as an actual schematic of an ITS sensor)

The 2-green 4-red blink code is for High Throttle Under range, and the corrective action suggested in the XCT Op manual is:

• High Throttle Over range & High Throttle Under range:
High Side of throttle signal is outside of acceptable window for that
throttle type. Check and/or replace throttle. Change throttle type to
correct throttle installed on car.

I suspect cart would still work if black and white wire on ITS sensor were returned to their original positions.

[CarterCrew]

ScottyB: The picture didn't post the first time because apparently you have to actually click upload (not just think about it!), I'll try again.
To clarify, I wasn't upset, I was merely pointing out that it is not error-proof.

JohnnieB: Thanks for the diagram, and in looking at it I would come to the same conclusion, it should work either way. I can tell you though, it didn't. With the wires in the positions as pictured in ScottyB's post, the controller saw 100% throttle and gave an error. Reversing the wires caused it to register correctly.

Could it be an indication of a failing throttle input?
Could that also be the cause of the controller failure?

[scottyb]

Could it be an indication you have the plug in backwards in the controller C5 ?
I know of no instance where the ITS caused a controller failure - the controller provides the power for the ITS

[JohnnieB]

Your picture shows J1 of the cart's wiring harness correctly oriented, but offset by one row and one space. The green wire is J1 Pin-10 and is plugged into C1 Pin-4. Fortunately the only external power in on J1 Pins 4 & 5, which are not plugged into anything on C1, so no damage was likely to have been done, other than possibly some physical damage to C1 Pin-2, which is one of the five keyed pins and the only conflict when plugging in with the one row and one space offset. Attached picture is J1 on a stock PDS controller.

When J1 is inverted (without any offsets) all 10 pins have a keying conflict and it is impossible to plug into C1, unless enough force is used to break the Molex connector shells.

---------------
The ITS circuit consists of three electrical parts, power source, ITS sensor and pedal position decoder. The power source and decoder are inside the controller while the ITS sensor is external to the controller.

The ITS sensor is described as a proximity sensor in the attached US Patent document. In a nutshell, as the plunger (iron slug moved by moving the accelerator pedal) is inserted into the sensor, the current flow through the ITS sensor increases (which means the dynamic impedance decreases).

I may be wrong, but I believe EZGO/Curtis use the ITS sensor as a variable resistor and the power source used is a constant voltage source while the decoder is fixed resistor on the return leg. As the ITS sensor's impedance decreases, the current flow increase through it and the fixed resistor in series with it inside the controller. The result is that the voltage on the return pin of the controller increases as the pedal is pushed. For a Curtis 1206MX (stock PDS controller) The voltage on J4 Pin-1 (White wire - power source) is supposed to be ~15V and the voltage on J4 Pin-3 (Black wire - decoder input) is supposed to be ~1.0V when solenoid clicks and ~3.0V when pedal is on floor.

I suspect Alltrax didn't want to pay royalties on every controller the built that could use the patented ITS sensor, so they came up with a "new and novel" way of using it that wasn't covered by either EZGO or Curtis patents. It appears that Alltrax uses a constant current power source and uses the voltage required to maintain the constant current flow through the ITS sensor to decode the pedal position. The result is the the voltage decreases as the impedance of the ITS sensor decreases. (IE: 10V pedal up and 6V pedal down.)

Basically, the power source and the decoder are on the same pin. Probably Pin-3.

The High Throttle Under range error means the voltage on Pin-3 is less than the 10V it ought to be with the pedal up. A current path in parallel with the ITS sensor would lower the voltage required to cause the expected current flow rate of a good ITS sensor.

I can see how the error occurs and how the throttle could be at 100% with pedal up, but I cannot come up with anything that will make the throttle percentage decrease as pedal is pushed.


It might be interesting to ask Alltrax if they know how it could happen.

Glad it is running.

[Rmcfeeley]

I have the same issue on my txt with Alltrax controller it's giving me a High/Low Throttle Input Under-range and Pedal 100% Error. Everything was working fine until I connected the controller to my laptop and attempted to adjust throttle settings, ever since then I haven't been able to clear the faults. Throttle settings is set for EZGO ITS. Any suggestions?

[VanillaXtract]

Originally Posted by Rmcfeeley

I have the same issue on my txt with Alltrax controller it's giving me a High/Low Throttle Input Under-range and Pedal 100% Error. Everything was working fine until I connected the controller to my laptop and attempted to adjust throttle settings, ever since then I haven't been able to clear the faults. Throttle settings is set for EZGO ITS. Any suggestions?

The exact same thing just happened to me. How did you fix it?