Solenoid clicks on with key

[jaman74]

I have a 2002 ez go cart with E300 on the data tag. My problem is the solenoid on the motor controller turns on when the key is turned on and placed in F or R and stays on the entire time no matter what the throttle pedal is at which is in good adjustment. The yellow and blue wires were chafed open against the battery hot side and unit quit driving. I repaired the yellow and blue wire but unit will only drive about 4 to 5 mph, takes off fast but slows down. Batteries are new and charged to 38.6 at the pack. The A- terminal has 38.6 volts at rest and drops to 19 at full throttle with rear wheels off the ground.
Is the solenoid suppose to only click and turn on with the throttle pedal? What’s causing it to go so slow. Also no fault codes with diagnostic mode and beeps four times to indicate performance mode.
Am I possibly looking at multiple component failure?
By the way this cart has the precision drive and Curtis 1206 MC.

[bronsonj]

Under load the pack should drop to 34 or 36 volts. Under load it shouldn't go to 19v nevermind with the wheels in the air.

So you either have a dead battery pack or a bad connection.
You said they are new, maybe you got a bum set? I'd check all the connections for corrosion or partially cut wires.

Can you measure the V of the individual batteries when it drops to 19v?

[JohnnieB]

The A- terminal is the controller's output terminal (marked M- on other controllers) and should have full battery pack voltage on it when pedal is pressed just far enough to energize solenoid. Dropping to 19V at WOT means the controller is only passing roughly 50% of voltage applied to the B+ terminal (38.6V). This is likely due to the fact the rear wheels are in the air and a PDS controller limits the motor to 4400RPM in freedom mode, so it is throttling back to keep the RPM below the max allowed.

The PDS controller supplies both B+ (yellow wire) and B- (blue wire) to the solenoid coil and will often energize the solenoid when voltage is applied to J1 Pin-8 (Keyswitch), but only for a short period of time. (5-10 seconds?)

In addition to energizing the solenoid when the pedal is pressed, the controller also energizes it whenever regen braking occurs.

In freedom mode (four beeps) you don't have regen braking when you lift your foot off the pedal, but it does occur going downhill if the motor tries to exceed 4400RPM.

If the cart starts to move with the pedal up, the walkaway safety kicks in and regen braking is applied to keep cart under about 2MPH so you can catch the cart you forgot to set the parking brake on. Also, the beeper beeps rapidly.

Crash stop is my term for it, I haven't found what EZGO calls it. If the key is turned off or the F/R is shifted, max regen braking occurs and the beeper beeps rapidly.

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Since the solenoid stays energized when a direction is selected and key is on, it is very likely that shorting the yellow and blue wires together and to the B+ cable took out the main coil driver in the controller.

Replace it with an XCT4840PDS (or larger) and replace the stock (85A) solenoid with one rated for 200A or more.

[jaman74]

First off I listed the wrong Curtis controller and can’t seem to go back and edit it. It’s is a Curtis part number 73326G02.
Didn’t say my pack was dropping to 19. That’s at the A- terminal on the controller. Pack only drops to 36.
My main question here is why is my solenoid engaging as soon as I put it in forward or reverse with key on. It does it with wires disconnected from throttle pedal microswitch and or the its and also the connector on the controller?

[JohnnieB]

"X" and "C" are side-by-side on a qwerty keyboard, so I figured it was a typo.

Your cart is a 2002 TXT PDS.

Apparently the blue wire on the solenoid is continuously connected to B- and when you apply B+ to the yellow wire via the F/R switch and Key is ON, the solenoid energizes.

Either the relay coil driver inside the controller is shorted or the blue wire is somehow connected to B- outside the controller.

[jaman74]

Just a quick follow up to the outcome. Replaced the motor controller and everything works great and completely as designed.

[Zincode]

Originally Posted by jaman74

Just a quick follow up to the outcome. Replaced the motor controller and everything works great and completely as designed.

Cool I was also thinking the micro switch in the pedal box was possible blame but apparently not. Good work...

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