medalist throttle to controller issue

highlandb

First of all, thanks for all your help BGW has provided. I have been reading since last fall and have had success with several projects. Current project I need some help with an intermittent issue. Cart is a 95 medalist series stock motor. Controller Alltrax NPX 4834EZ new old stock, HD F&R switch new ( both thanks to Carts Unlimited), new batteries. New ITS and Micro switch in the pedal box. Cart is on jackstands as I am awaiting brake cables. Cart ran fine after F&R install let it sit on stands overnight then nothing. The LED on the controller blinked as it should 4 green then solid green but no motor turning. Went to track down the four pin connection from the pedal box to the controller to clean and or eliminate, now we are running again. While it is running I went to take down some numbers to try to isolate the issue and feel better about my self. At B- and M- I get full pack at the click of the solenoid and as the pedal is pushed down the volt goes down to zero. My concern is I measured the white and black( labeled throttle one throttle two) at the controller. I got .56 with the pedal up and 4.92 with the pedal down. This is while the cart seems to be working properly motor runs in forward and reverse. I thought I read some where that it should be 10V up and 6V down? I have taken the four pin connector apart and put it back together and right now everything seems to be ok, yet I haven’t really fixed anything. Wondering if there is a better way to diagnose the issue. Thanks in advance for any advice

BGW

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yurtle

Others can speak to your voltage readings, but if you determine it is the MOLEX connector, you can simply remove it and solder and tape the wires together. There is no real need for the connector, as an owner.

highlandb

thank you, that was my intent but while it is working I would like to test with a known point of reference, and maybe isolate the variables. until my patience runs out ha ha

cgtech

Disregard... Medalist, not marathon... Had a blonde moment.

highlandb

Last night, cart running fine on jack stands, in garage, this morning after twelve hours untouched I have same issue, controller lights good, but no engine go. I removed the four pin connector(molex?) from the pedal box to the controller, tied wires together, same thing. No go on engine, any ideas where to look next, would be appreciated. I am going to swap out ITS now thanks in advance for any help

JohnnieB

Measuring between the black and the white wires going from controller to the pedal box, with the wires connected to the NPX controller, you should get 10V pedal up and 6V pedal down.

I'm pretty sure it is an isolated constant current power supply, so you might get some strange readings if you are referencing your meter to the main negative terminal of the battery pack.

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The fact that the voltage between B- and M- is pack voltage with pedal up and Zero with pedal down, indicates the controller is getting a good set of voltages from the ITS sensor in the pedal box, but we don't know what it is when the cart is misbehaving.

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If the ITS sensor has any hairline cracks in the potting compound, moisture can get onto the PC board inside it and cause all sorts of strange things. Had it been raining or the humidity been high when the cart was misbehaving?

Attached is a schematic of what is inside an ITS sensor.

Attached Images

ITS sensor - Schematic.JPG (88.3 KB, 0 views)

highlandb

Thank you, yes humidity is high, Today when the cart was not running, I did three things to get it running.
1 I removed the negative cable from the battery pack which has a ANN 250 fuse attached for the controller.

2. I removed the resisitor and the cable going to B+ on the controller

3 I connected and reconnected the microswicth at the pedal box

waited @ hour reconnected and things are running again on jackstand inside garage

I am waiting for it to quit working again, as to try and isolate the issue, any ideas would be greatly appreciated. it seems as if it sits for a period of time in the am it wont run.

highlandb

Didn't proof read my reply, excited, as I am waiting for the cart to not work properly, the cable and resistor was removed from the large post off the solenoid. then all was reconnected then as now all works fine. I may have a different issue than I originally thought, again thanks for any guidance

highlandb

FWIW, again I get up this morning and the cart doesn't run, after sleepless nights, I thought the one consistent thing I have done to get it running is to remove the negative cable off the battery pack which has the ANN 250 amp fuse for the alltrax controller. I tested the pack voltage at the battery post, before the fuse 37.9, at the end of the fuse erratic readings, could this fuse be the cause a bad connection inside? Today the only thing I did was remove the fuse from the end of the battery pack and place it on the B- on the controller, voila it runs. the resistor on the coil would keep enough power to light up the controller but fuse would not cooperate to allow constant flow. if this is not plausible please let me know it would be appreciated, anyway off to find a new fuse, or can I run this without the fuse?

yurtle

You can certainly run without the fuse. Try it that way for a few weeks, and if the problem never resurfaces, it could be a partially bad fuse. If you like having the safety of a fuse, simply replace it. First, I'd ensure the connection to your fuse was solid.