Motor stops running

[CoolDaddy]

When I press the accelerator the cart starts to move then quits. If I press the pedal 1/4 of the way then it will roll. Once I go past that it stops.
The blue/white wire at small solenoid post gets pulled low when pressing the accelerator (heard audible click and tested with meter). Once the accelerator is pressed more than 1/4 the low on this terminal goes away.

This is a 2006 Electric 48V Club Car DS with IQ, 19.2 speed kit and Batteries about 1.5 years old.
Curtis 1510A-5250 controller.

Here's what I have done so far:
Checked wiring and connections.
Checked battery pack voltages 48V.
Checked cables and connectors.
Checked Solenoid Found no issues but replaced with new one.
Checked MCOR1 found no issues but swapped with known good one. My original MCOR1 is in another cart and running fine.
Tested voltage inputs at the controller and found no issues.
Checked Motor for shorts (ohms)
A1-A2 = 1.7
F1-F2 = 0.2
A1/A2 - F1/F2 = .363M
A1/A2 - Motor body = 247K
F1/F2 - Motor body = 144K

I do have access to a Club Car Villager controller (1510A-5351). I'm not sure if they are compatible so didn't want to swap it.
a thoughts or suggestions are greatly appreciated.

[Gregorio]

It sure sounds like a bad MCOR. I know you said you swapped the MCOR with another known working one but there is an easier way. Pull the 2-pin connector from the MCOR with the blue wires. Jump the cart side of the connector with a small length of wire. If the cart runs this way, you have a bad MCOR.

[CoolDaddy]

Gregorio,

Thanks for the reply. I just want to make sure that you are talking about jumping the 2 pin connector basically just shorting it out. Blue to Green.

[CoolDaddy]

I jumpered the MCOR 2 pin connector wires as suggested. It did not fix the problem. It still does the same thing in both foward and reverse. I have doubled checked the 3 pin connector reading both voltage and ohms. It appears to be performing as expected.
Any other thoughts or suggestions. I'm willing to try anything. It's baffling me.

[TahoeDawgZ71]

Sounds like low voltage to me. What's the total voltage of the battery pack? I know you said 48V, but 48V is dead. What's the actual voltage number on the meter?

[mrgolf]

If you have one bad cell in one of your batteries the voltage can check good on a meter, but when you put a load on the batteries that bad cell can cause the batteries to go almost to zero volts. Check batteries with meter this way.

[Raystar57]

You have some high resistance conductive path in the motor.
I think the motor is contaminated with carbon from excessive brush wear.
Are these readings taken with no wires connected to the motor?
If so then you need to open it up and inspect the brushes and clean it out.
There should be no resistance (infinite) from A's and F's to the case.
There should be no resistance (infinite) from A's and F's to each other.
The carbon buildup from brush wear can cause this conductivity.

This may not be the full issue but I would inspect it to be sure.
You may need a new set of brushes and a commutator cleanup.

[Golf cart guy]

Originally Posted by TahoeDawgZ71

Sounds like low voltage to me. What's the total voltage of the battery pack? I know you said 48V, but 48V is dead. What's the actual voltage number on the meter?

This is what I was thinking, one bad battery that craps out under a load- Id check that before I went any further.

[CoolDaddy]

Great suggeestions and right on the mark.

I had 50.9V on the battery pack. With the rear wheels raised and my meter hooked up across the battery pack I pressed the accelerator. The voltage went from 50.9V down to 0v and open as the accelerator was pressed.
To further test my wiring I disconnected the + and - of my battery pack and on another carts battery pack. Connedcted jumper cables from another cart's battey pack to my carts + and -. I then pressed the accelerator and the cart ran as expected.

I posted this in detail in hopes to help someone else with a similar problem.

Verify your batteries under load!!!!

Raystar57 makes some good points about the motor. Those readings concerned me also. They were all taken with the wires off. I would have expected infinite reading across those points. That will be my next project.

Thanks for the help. This forum has been very educational.