PDS cart mysterious loss of power

[little1406]

My early 2000's (maybe 2005) stock PDS cart suddenly developed a problem which caused it to loose power and even come to a stop despite the pedal being floored. Releasing the pedal and pressing it again always caused the cart to move again....sometimes for a good while, sometimes for only a fraction of a second before it would stop again, despite having the pedal fully depressed.

I replaced the ITS. No change.

I replaced the stock Curtis 1206MX controller with a drop-in Alltrax NCX controller for this cart. No change.

Any idea what is causing this vexing problem?

Thanks

[kgsc]

I would have suspected the speed sensor but the Alltrax took that out of the equation. I would check the solenoid out next. Flip the run tow switch to tow, remove one side of the precharge resistor from the solenoid, put the cart on jack stands, flip it back to run and with some help and a volt meter check to see if you have voltage on both sides when the pedal is pressed.

[scottyb]

Sounds like the cause could be corrosive build up or moisture in the 4 pin plug between the throttle box and the solenoid.

Does the solenoid drop out (click) when the cart cuts off?

[smokey tennis shoe]

I had a similar sitch with a pds. It was driving me crazy. What it ended up being, was the wire on the microswitch, inside the pedal box. While i was messing around with it, i hit the wire and it dropped out. The terminal on the microswitch was lose.

It would move a little and cut out.

I replaced the switch, and fixed it.

[scottyb]

Whether or not the solenoid is dropping out is a key piece of the puzzle. THis lets you know if the trouble is in the solenoid activation circuit or the throttle signal, speed sensor, or control panel power problem

[little1406]

Thanks guys....the suggestions got me going again on diagnosis. Previously, I did not think that the solenoid was dropping out....maybe I didn't hear it. Today, I starting driving it around with the seat removed and a small piece of plywood to sit on. First, I tried connecting the voltmeter across the solenoid....to see if its contacts were loosing contact. I managed to get the cart to come to a complete stop with the pedal floored and the voltage across the solenoid was still nearly zero: contacts NOT the problem. Then I checked everything in the throttle box again and used the voltmeter to monitor the voltage across the microswitch while the loss of power was occurring: no problem with the microswitch contacts. And I checked the ignition switch....and the Forward/Reverse switch similarly: no problem. Then I finally noticed that the solenoid was dropping out sometimes during these loss of power events.....so I got the cart into that state where the pedal is floored but the cart is sitting still and checked the voltage across the solenoid coil: ZERO! Tracing the circuit that delivers power to that coil, I encountered the RUN/TOW switch and, sure enough, that switch was so old and tired that it was making intermittent contact. I just connected the run side wires together permanently and disconnected the tow side wires (so there wouldn't be a conflict) and the **** cart ran all over the place all day long without a single glitch!

Frankly, I'm not sure how the peculiar symptoms I observed could be caused by a glitchy RUN/TOW switch but that seems to be what fixed the problem. BTW, the ALLTRAX controller was helpful in this diagnosis. When the problem occurred, I observed the LED on the ALLTRAX was giving three red flashes, which is an error code that means the throttle has not gone to zero yet on this power cycle. That meant that something was causing a power cycle to occur while I held the throttle pedal down.....and it turned out to be the glitchy RUN/TOW switch.

Now that I think about it a bit, a brief glitch...which I didn't hear....would cause the controller to drop out and the cart to coast to a stop....exactly what I was observing.

Sigh......