Solinoid help

[Mouse4x4]

So I think I have a bad solinoid, after a long run and then let off the pedal to stop sometimes I press it back down and don't get anything, no click from the solinoid or anything. If I keep the pedal mashed down and smack the seat off we go like nothing happened. I checked all connections, solinoid and controller look fairly new. Cart is new to me so I sure of history. Is this the syptom of a bad solinoid

[georgia088]

You’re going to have to give more info. Type of cart/motor? Which controller? Voltages etc.

[Mouse4x4]

All stock trx 2003 I believe series setup 36volt has a forward reverse selector with a rod to the shift mech and then a factory controller with solinoid mounted in front of it

[georgia088]

If it’s a txt? Series. This is a good thread with a wiring schematic.

https://www.buggiesgonewild.com/showthread.php?t=71254

There are several micro switches (pedal switch, key switch, reed switch (in charge port) and f/r switches these are shown in schematic you can check to make sure the solenoid is getting what it needs to engage. From my understanding the solenoid should engage on these series carts without any input from the controller. So, check your wiring and micro switches.

[JohnnieB]

Here is a schematic of a series drive with the solenoid activation circuit highlighted.

One side of the solenoid's coil is permanently connected to B-, so all that is need to activate it is B+ applied to the other side of the coil, but B+ has to go through four switch to get there.

[georgia088]

Originally Posted by JohnnieB

Here is a schematic of a series drive with the solenoid activation circuit highlighted.

One side of the solenoid's coil is permanently connected to B-, so all that is need to activate it is B+ applied to the other side of the coil, but B+ has to go through four switch to get there.

Jb- I know this isn’t my cart, but trying to understand how it works. I understand how the solenoid activates through the 4 switches, but once it activates what happens? The large wires on the solenoid go to the controller? And the controller adjust the current to the motor based on what it receives from the pedal input? Are these series cart foot pedals potentiometers that send signal to controller?

[JohnnieB]

Originally Posted by georgia088

Jb-

1. I know this isn’t my cart, but trying to understand how it works.

2. I understand how the solenoid activates through the 4 switches, but once it activates what happens?

3. The large wires on the solenoid go to the controller?

4. And the controller adjust the current to the motor based on what it receives from the pedal input?

5. Are these series cart foot pedals potentiometers that send signal to controller?

1. The following is for a series drive. If you want a similar explanation for a sepex drive (like your cart has), start a new thread so future readers of this thread don't get confused.

2. The KSI (Key Switch and Interlocks) voltage that energizes the solenoid also turns on the controller. Red wire from solenoid small terminal to Pin-4 in this case, as shown on schematic posted above.

3. The output of the solenoid's large terminals got to controller and motor (via F/R switch).

4. The controller is an Amp limiting device. The RPM the motor's armature is spinning at determines how many amps the motor can draw.

The controller's output to the motor is PWM DC (Pulse Width Modulated DC) that varies in duty cycle for 0% to 100% according to the pedal input.

The DC pulses go from 0V to whatever the battery pack voltage is about 18,000 times per second and the ratio of off (0v) to on (38.2V for fully charged 36V pack) determines how many Amps the motor is allowed to draw while the motor's RPM determines the max Amps the motor can draw when the duty cycle is at 100%.

5. Pre 1994.5 EZGO cart with controllers had a 0 to 5kΩ throttle. After 1994.5 they had an ITS (Inductive Throttle System).

Attached is a block diagram of a Curtis 1204/5 controller, which was used by EZGO prior to 1994.5 and a block diagram for the Curtis 1206 that was used after 1994.5 would be a near twin. All series controllers work roughly the same at the block diagram level.

[georgia088]

I understand it all except I can’t figure out what are the “large wires” on the solenoid are on the schematic. I don’t see any wires going from the solenoid to the f/r switch on the schematic. All the wires going to f/r are either going to controller or motor that I see. I know I’m missing something but can’t figure it out.

[JohnnieB]

Originally Posted by georgia088

I understand it all except I can’t figure out what are the “large wires” on the solenoid are on the schematic. I don’t see any wires going from the solenoid to the f/r switch on the schematic. All the wires going to f/r are either going to controller or motor that I see. I know I’m missing something but can’t figure it out.

Attached is a schematic with high current cables (thick cables) highlighted.

If you start at the battery pack's most positive terminal and follow the highlighted cables, you'll find a single path that goes through the solenoid's contacts (which are connected by a dotted line to the the solenoid's coil) through two of the four sets of contacts in the F/R switch, through the stator windings, back to the F/r switch and through the other two sets of contacts, to the armature and then to the M- terminal on the controller. The MOSFETs are electrically located between the M- and B- terminals and from the controller's B- terminals back to the B- side of the battery pack, completing the series loop.

FWIW: The speed control "Valve" is located in the B- portion of the series circuit.

[georgia088]

Originally Posted by JohnnieB

Attached is a schematic with high current cables (thick cables) highlighted.

If you start at the battery pack's most positive terminal and follow the highlighted cables, you'll find a single path that goes through the solenoid's contacts (which are connected by a dotted line to the the solenoid's coil) through two of the four sets of contacts in the F/R switch, through the stator windings, back to the F/r switch and through the other two sets of contacts, to the armature and then to the M- terminal on the controller. The MOSFETs are electrically located between the M- and B- terminals and from the controller's B- terminals back to the B- side of the battery pack, completing the series loop.

FWIW: The speed control "Valve" is located in the B- portion of the series circuit.

Ah! So the circled portion of my attached image are the “large terminals” of the solenoid?