Lots of times, when working on a golf cart you get into a situation where the batteries seem to be fine, the solenoid is working fine, but the cart still doesn’t go anywhere. In a situation like this, the first thing you need to do is to determine whether the controller is capable of working or not (regardless of what is happening with the F/R circuitry or the motor). One of the most useful tips that you will find in “Electric Golf Cart Repair 101 (and a half)” is in Appendix 5 (The Tool). It is a fairly long appendix with a detailed description of Pulse Width Modulation (PWM), but the bottom line is that there is a very easy way to check to see if a series controller is working or not. You place a 60 watt incandescent light bulb in a socket and connect it between M- on the controller and B+. Then jack up the rear wheels and put the cart in a normal mode of operation mode (in forward with key switch on). Then watch the bulb while you move the accelerator. If the controller is working, the bulb will go from “off” to “well lighted” with advancement of the accelerator. Even if the F/R switch is open, the brushes are open in the motor or there is a break in the wiring, the controller will still work. The loading (impedance) of the bulb is enough to satisfy the needs of the controller, so it will still provide PWM and work. Bingo, you’ve got a series motor controller tester. It will work on Club Car, E-Z-GO, Yamaha, anything with a series controller. As long as the controller has B+, B-, Ignition (pin 1), and throttle information (pins 2 and 3), it will light the bulb (which is between B+ and M-), which proves the Pulse Width Modulation is working (or not).
Ron Staley has published the following books, and you can get more information about them by just clicking on each title below:
Electric Golf Cart Repair 101 (and a half)
Techniques, Tips, Tools and Tales
Gas Golf Cart Repair 101 (and a half)
Techniques, Tips, Tools and Tales
4-Stroke Golf Cart Engines Explored
What Makes Them Tick
By an old Slot Machine Mechanic