EZGO TXT Series bucking under load (not batteries)

[PLAYRR2000]

For future reference in case someone finds this with a similar problem. I changed...

Batteries
All cables
Solenoid
Controller
F/R switch
ITS sensor
Eliminated reed switch
Eliminated 4 pin connector on throttle harness

Still had the same issues under load.

I was about to accept that it had to be the motor since that was really the only thing left. On a whim, I went ahead and pulled the ignition switch to inspect the wiring on it, which appeared to be perfect. After putting the switch back in, the cart operates 100%. This makes absolutely no sense to me since the issue was load dependent and I wouldn't think there would be any real load on the ignition switch, but as they say... It is what it is.

[sthreatt]

A series cart does not have regenerative braking.

[PLAYRR2000]

Apologies for even mentioning 40mph. I do not roll my cart 40mph. I only described it that way to illustrate the fact that it will basically "run away" as fast as you let it go when going downhill, it does not engine brake like most other carts I have driven do. I originally wondered if that was normal or an indication of another issue. That question has now been answered numerous times, that it is in fact normal for these carts. I am now very aware that should I ever have the desire to let it get up to excessive speeds I risk damaging the motor. Thanks to all that have made that painfully clear. I hope that maybe someone in the future can get something out of the actual issue in this thread, the bucking under load. Cheers!

[JohnnieB]

From reading through this thread I see two sets of symptoms being given.
1. Bucking under load.
2. Solenoid, and maybe the controller, dropping out under load.

The first one is typically caused by problems in the high amp circuit and the second one is typically cause by problem(s) in the wiring harness and switches.

If the solenoid clicks when the misbehaves, than #2 is the more accurate symptom.

It is true the driving conditions does not change the load on the circuit the keyswitch is in, but the battery pack voltage applied to the keyswitch circuit drops when the high amp circuit is under load, so there is an indirect impact due to battery pack loading.

If the voltage in the keyswitch circuit drops low enough, the solenoid will de-energize and the controller has a low voltage cutoff.

If the keyswitch circuit had enough resistance in it to drop the voltage to just above the cutoff point and the battery pack voltage dropped under load, that could trigger the solenoid dropping out and the controller shutting down.

Monitoring the voltage on the solenoid's small terminal with the red wire or the controller's pin-4 while driving might have identified the issue.

[Bama Brad]

Originally Posted by PLAYRR2000

For future reference in case someone finds this with a similar problem. I changed...

Batteries
All cables
Solenoid
Controller
F/R switch
ITS sensor
Eliminated reed switch
Eliminated 4 pin connector on throttle harness

Still had the same issues under load.

I was about to accept that it had to be the motor since that was really the only thing left. On a whim, I went ahead and pulled the ignition switch to inspect the wiring on it, which appeared to be perfect. After putting the switch back in, the cart operates 100%. This makes absolutely no sense to me since the issue was load dependent and I wouldn't think there would be any real load on the ignition switch, but as they say... It is what it is.

So you are saying that you replaced all this only to find that it was something in the key switch? Man, glad to hear you figured it out, but that was really expensive, right?

[PLAYRR2000]

Yeah, it was indeed expensive... and frustrating. However, I did the SR48500/400 combo with the HD F/R switch from Carts Unlimited which was the bulk of it so I'm well ahead of where I was and will now be able to switch to 48v, so it wasn't all sunken cost just to get the thing driving correctly.

[PLAYRR2000]

Interesting info JohnnieB. I will look for that if it ever creeps up again. I didn't really do anything to the switch itself other than remove/install, reseat connectors so there's a chance I haven't seen the last of it, but I know where to look now. I will keep your troubleshooting info in mind. I know for a fact the solenoid was clicking off and on with the original equipment, which is when I answered the question that yes, it in fact was. However, after the switch to the stuff I got from you it didn't seem to be even though I was getting the same jumpy, bucking type behavior, so I guess it is possible I had 2 seperate issues causing the same type symptom.

[JohnnieB]

Originally Posted by PLAYRR2000

Interesting info JohnnieB. I will look for that if it ever creeps up again. I didn't really do anything to the switch itself other than remove/install, reseat connectors so there's a chance I haven't seen the last of it, but I know where to look now. I will keep your troubleshooting info in mind. I know for a fact the solenoid was clicking off and on with the original equipment, which is when I answered the question that yes, it in fact was. However, after the switch to the stuff I got from you it didn't seem to be even though I was getting the same jumpy, bucking type behavior, so I guess it is possible I had 2 seperate issues causing the same type symptom.

You've got me confused with ScottyB. He lives on the left coast and owns Carts Unlimited while I live in WV and used to fix medical equipment.

If it does start acting up again, record a data log (continuous sampling rate) and it'll show what is dropping out.

[sthreatt]

Originally Posted by JohnnieB

You've got me confused with ScottyB. He lives on the left coast and owns Carts Unlimited while I live in WV and used to fix medical equipment.

ScottyB and JohnnieB !
Hadn't paid any attention to y'all having the same last name. y'all kin ?

[PLAYRR2000]

Lol, I sure do! I guess I just saw the B and connected the two because I've seen a lot of your posts while looking for answers.