Friend of mine's grand-dad uses a 36V EZ-GO to get around his property (check the mail, etc etc). He thought the batteries were getting weak so he replaced them (they were, by all accounts, bad) and upon driving the machine around the house, it died.
It sat in the front yard for a while when said friend called me into the mix. He brought it over and I sat about "diagnosing" the machine. I charged up the pack and fixed a few weak pack cable lug terminals (solder and heat shrink). The machine's solenoid clicks with the key switch on when you step on the pedal but no go-go.
I unhooked the leads from the motor and tested the rotor terminals. Wacky readings had me suspecting a bad motor. While rotating the motor the rotor resistance was jumping between 70kohms and dead short. I pulled the motor out and pressed out the rotor. The commutator was burnt up really bad and I understand that EZ-GO does not consider any part of the motor to be a service item but..... well I threw it in the lathe to turn the commutator and ended up having to remove a fair amount.
I devised a way to scrape out the mica below each commutator bar and respun it to check dead true. After the rework, the cummutator bars all had about 4ohms of resistance and none were dead short. While in there I measured and lubricated the brushes and refiled them smooth to mate to the turned comm.
Upon reinstalling the motor, I still had a no-go condition so I whipped out EZ-GO's 280 page service manual (OMG, WHAT A JOKE!) and set about checking out the system. What it boils down to is that the pin outputting power to the ITS isn't putting out 13-15 VDC, it's putting out the full pack voltage. Instead of .4-.6 VDC at the ITS I'm getting pack voltage. The motor controller is of course, also not grounding out the system so I'm getting +36VDC floating off on every terminal on the F&R switch and motor.
In order to test the functionality of the rest of the stinking system I jacked up the rear and unhooked the M- terminal from the controller and stuck it straight onto the pack B- terminal. The rest of the system is functioning properly (F&R direction, key switch, pedal microswitch) just no speed control on the pedal, full on both directions.
I suspect a failed motor controller control board and load center.
Now, I want to make sure that this is the only issue before I recommend a repair method. Anyone know the correct resistance figure for the ITS separate from the reference voltage (I don't have a functional motor controller to use to provide said voltage so I need an independent verification) like a base resistance and then a "plunger fully inserted" resistance so I can check that part offline.
I know it's sort of taboo but how in the heck do you get the cover off of the controller? It's a EZGO 5 pin TXT. I'm pretty handy with jelly bean parts and a soldering iron so pulling the cover off doesn't scare me but I'm not a fan of butchering the cover if there is actually a magic word to getting it apart.
It sat in the front yard for a while when said friend called me into the mix. He brought it over and I sat about "diagnosing" the machine. I charged up the pack and fixed a few weak pack cable lug terminals (solder and heat shrink). The machine's solenoid clicks with the key switch on when you step on the pedal but no go-go.
I unhooked the leads from the motor and tested the rotor terminals. Wacky readings had me suspecting a bad motor. While rotating the motor the rotor resistance was jumping between 70kohms and dead short. I pulled the motor out and pressed out the rotor. The commutator was burnt up really bad and I understand that EZ-GO does not consider any part of the motor to be a service item but..... well I threw it in the lathe to turn the commutator and ended up having to remove a fair amount.
I devised a way to scrape out the mica below each commutator bar and respun it to check dead true. After the rework, the cummutator bars all had about 4ohms of resistance and none were dead short. While in there I measured and lubricated the brushes and refiled them smooth to mate to the turned comm.
Upon reinstalling the motor, I still had a no-go condition so I whipped out EZ-GO's 280 page service manual (OMG, WHAT A JOKE!) and set about checking out the system. What it boils down to is that the pin outputting power to the ITS isn't putting out 13-15 VDC, it's putting out the full pack voltage. Instead of .4-.6 VDC at the ITS I'm getting pack voltage. The motor controller is of course, also not grounding out the system so I'm getting +36VDC floating off on every terminal on the F&R switch and motor.
In order to test the functionality of the rest of the stinking system I jacked up the rear and unhooked the M- terminal from the controller and stuck it straight onto the pack B- terminal. The rest of the system is functioning properly (F&R direction, key switch, pedal microswitch) just no speed control on the pedal, full on both directions.
I suspect a failed motor controller control board and load center.
Now, I want to make sure that this is the only issue before I recommend a repair method. Anyone know the correct resistance figure for the ITS separate from the reference voltage (I don't have a functional motor controller to use to provide said voltage so I need an independent verification) like a base resistance and then a "plunger fully inserted" resistance so I can check that part offline.
I know it's sort of taboo but how in the heck do you get the cover off of the controller? It's a EZGO 5 pin TXT. I'm pretty handy with jelly bean parts and a soldering iron so pulling the cover off doesn't scare me but I'm not a fan of butchering the cover if there is actually a magic word to getting it apart.