EZGO TXT Non-PDS Help/Questions

[JoeBleaux]

2nd UPDATE:

Key on, F/R switch in F, pedal to solenoid click produces the following on the F/R switch studs: at A, pack voltage (38.9), at B, .61 volts, at C, .61 volts, at D, .61 volts. With the F/R in R, the only change is at D, which then is pack voltage. I think I mentioned that I removed the F/R switch and while it looked clean with clean contacts, I did hit the contacts with a Scotchbrite while it was out. It is wired according to the labels on the cables, which also match the schematic you posted (and also matched the one I found).

[rib33024]

JoeBleaux you should be able to send and revive PM's

[JoeBleaux]

Originally Posted by rib33024

JoeBleaux you should be able to send and revive PM's

I can - thanks!

[JohnnieB]

Originally Posted by JoeBleaux

UPDATE - Here are the actual readings from the cart:

Meter leads on B- and M-, key on, F-R in F, pedal pressed just to solenoid clicking on, voltage jumping around under 1 volt, pressing the pedal further decreases the voltage and seems to stabilize it a bit at full-down. When the pedal is allowed to return to full up, the voltage stabilizes at about .33 volts, within .05 volts (slightly different voltage with multiple readings) and starts to drop off in .01 volt increments - like a cap discharging???

It seems the last place I have pack voltage is inside the controller - is there any way to check it? I found nothing on the guts of the controller, so I am assuming that this isn't a fuse inside - correct?

Bottom line is that it would seem the controller isn't working properly - correct?

The voltage between the controller's B- and M- terminals is external to the controller. It will exist whether the controller is good or bad, or powered up or not; Unless the MOSFETs are shorted or turned on.

Disconnect the cables on the B- and M- terminals and connect the DVM between the two unattached cables. If you do not read full battery pack voltage now, you absolutely, positively have an open somewhere in the high current cables, connections or contacts.

Attached is a block diagram of a series controller. It is for a Curtis 1204 rather than a 1206, but they all work about the same.

[JohnnieB]

Originally Posted by JoeBleaux

2nd UPDATE:

Key on, F/R switch in F, pedal to solenoid click produces the following on the F/R switch studs: at A, pack voltage (38.9), at B, .61 volts, at C, .61 volts, at D, .61 volts. With the F/R in R, the only change is at D, which then is pack voltage. I think I mentioned that I removed the F/R switch and while it looked clean with clean contacts, I did hit the contacts with a Scotchbrite while it was out. It is wired according to the labels on the cables, which also match the schematic you posted (and also matched the one I found).

The contacts in your F/R switch are not making contact. Otherwise, there would be 38.9V on all four studs.

Make sure the the cam is being turned all the way into the mechanical stops.

[JoeBleaux]

3rd UPDATE

First and foremost, thanks for the help! This is getting weird. I got the cart to go...all of 15 feet. Here's what I found:

Someone had spliced the 4 cables to the motor at the mid-point of the cables and had done a strange, overkill job of reconnecting them or there was something originally in the circuit that was removed and the lugs bolted together. Three of the wires to the motor had lug eyes crimped on and heatshrinked, then bolted together with stainless bolts, lockwashers and nuts and then carefully and thoroughly over-wrapped the connections with 3M-type rubber tape. The fourth was connected with a heavy-duty copper butt crimp connector with two layers of industrial-duty heatshrink and again, overwrapped. This connection had failed - tip of the hat to JohnnieB on tracing the high-current circuit. You couldn't see these "joints" because they were ziptied in place under the small "secondary panel" between the motor access panel and the battery/control area.

Anyway, I took the F&R switch out to really clean and examine it (and I am 95% sure it is OK) and I figured I would disconnect the other ends from the motor and examine the cables. That's when I found the splices and failed connection. I built new 4 gauge cables (the original was about 6, not gauge marked, but the connection points were factory printed on them, along with a <part number?>) and sure enough, the cart ran...for 15 feet...then died.

Now I'm getting 20-21 volts through the resistor on the controller side of the solenoid and the resistor is getting warm-to-hot, but the solenoid seems to be working (it passes pack voltage when the pedal is pressed). I removed the resistor (it metered at 251 ohms), but still have "click and no go." When the pedal is pressed and the solenoid clicks, I get pack voltage at all four lugs on the F&R switch. With the pedal up, I get about 7-8 volts everywhere, which I guess is the caps in the controller.

I'm missing something, but what?

[JoeBleaux]

Originally Posted by JohnnieB

The voltage between the controller's B- and M- terminals is external to the controller. It will exist whether the controller is good or bad, or powered up or not; Unless the MOSFETs are shorted or turned on.

Disconnect the cables on the B- and M- terminals and connect the DVM between the two unattached cables. If you do not read full battery pack voltage now, you absolutely, positively have an open somewhere in the high current cables, connections or contacts.

Attached is a block diagram of a series controller. It is for a Curtis 1204 rather than a 1206, but they all work about the same.

Thanks for all the help and info, but the internals of the controller are above my pay grade. I have decent basic electrical knowledge but no real electronics knowledge, i.e., I can wire home/commercial to code, I know basically what a resistor, cap and diode are, but when it comes to board-level electronics troubleshooting, not so much. But please see my latest update and again, thanks!

[JoeBleaux]

I previously wrote:

Originally Posted by JoeBleaux

You couldn't see these "joints" because they were ziptied in place under the small "secondary panel" between the motor access panel and the battery/control area.

More weirdness - what I called the "secondary panel" is actually part of the original motor cover. However, it appears that the original cover was carefully cut at the "drop-down" into the battery area, with two extra screws used to hold it place separately from the main part of the cover. In other words, my motor cover is in two pieces with seven screws rather than one piece with 5 screws.

I have no experience with TXT carts, but this and the splices in the motor cables make me really wonder if something wasn't installed and removed between the F&R/M- and the motor. Anyone have any ideas/thoughts/guesses (or even SWAGs)?

[JoeBleaux]

Originally Posted by JohnnieB

The contacts in your F/R switch are not making contact. Otherwise, there would be 38.9V on all four studs.

Make sure the the cam is being turned all the way into the mechanical stops.

I worked a bit on it this morning, and now, I'm getting less than 1 volt between B+ and M- on the controller with the pedal in any position from just enough to activate the solenoid to full down. Isn't the voltage between them supposed to go from around 40% to nearly pack voltage as the pedal is pressed to full throttle?

[JohnnieB]

Pictures would help.

In your cart, there is a single current path, starting at the B+ terminal on the battery pack through the solenoid contacts, to the F/R switch and through two sets of contacts in the F/R switch to the Stator windings in the motor, out the other end of the stator windings back to the F/R switch and through two more sets of contacts to the M- terminal on the controller, through the MOSFETS inside the controller to the B- terminal and ending at the B- terminal on the battery pack.

Basically we are troubleshooting 13 pieces of wire connected in series with some lumps in it.

I'm going to suggest bypassing some of the lumps, so jack the rear tires off the ground and put on jackstands so you don't end up with a runaway cart.

Connect the cable from battery B+ to the controller side large terminal on the solenoid. That eliminates the solenoid contacts.

If the problem stays the same. reconnect the cables on the solenoid back to normal.

------------
Then on the F/R switch, connect the cables on the A and D studs together and connect the cables on the B and C studs together. That eliminates the F/R contacts.

If the F/R switch was is the problem, the cart should run now, but only in one direction.

If the problem stays the same, leave F/R cables as is and move the cable on the controller's M- terminal to the B- terminal (Both cables on same B- terminal) This eliminates the controller, so the motor will get hit with full battery pack voltage and there will be no speed control.

If those bypasses don't identify the problem, then the problem is in the cables and their connections, or the motor.