1996 Series DS 48V won't move on ground, wheels barely move on jacks

[dschron]

Guys

I am working on a 96 Series 48v (has large forward/reverse knob). The cart stopped working on them and a friend told them it was the speed controller, which has NOT been replaced. I went through the troubleshooting guide from start to finish and can't find anything wrong with it other than the pot resistance high when pedal is fully down but does increase from open with pedal up to high with pedal down. It has a "continuously variable potentiometer", NOT a VGlide or MCOR. What I've discovered is, on the ground when the go pedal is pressed, nothing. On jacks when the pedal is pressed the right rear turns very slowly and can be stopped with your foot. Pack voltage is over 50 volts at rest and when pedal is depressed. Solenoid clicks, controller output voltage increases to pack voltage when pedal is fully depressed. I checked half speed reverse limit switch and resistor, all good. Checked for shorted motor A1,A2, S1, S2 to case as well as continuity between A1,A2 and S1, S2 with no issues. I'd think if it was the high resistance in the pot it would still vary speed as pedal depressed but doesn't seem to. I am wondering if this is a bad motor issue.

This is the potentiometer test:

Test Procedure 9 - Continuously Variable
Potentiometer:
1. Disconnect the three-wire connector (connects
the potentiometer to the Forward/Reverse wire
harness) from the Forward/Reverse wire harness.
The connector emerges from under the
floorboard into the battery compartment below
the charger receptacle on the front seat support
panel (Figure 17-9).
2. Connect multi-meter, set to “ohms” position,
between the purple and yellow wire terminals.
Resistance should read between 150 and 300
ohms at exactly the point that the limit switch is
activated.
3. Depress the accelerator to the floor; potentiometer
resistance should measure between 4600
and 6400 ohms.


I got:

Pedal up- open
switch activated- all over the board from 500 ohms to 1.5 k ohms
pedal full down - 7k-8k ohms

any ideas?

[dschron]

OK an update. I disconnected the A2 off the motor and checked B+ to M-. With key off and switch in neutral, I got 44 volts. When I turned key on, F&R in FWD, and stepped on throttle, voltage rose to 51.3 volts. Doesn't this tell me that the controller is good? What I can't grasp is, with cart on jacks, only the passenger side wheel turns and relatively slowly. I can hold the tire and stop it from turning. Shouldn't both wheels be turning? Is there a way to check voltage actually at the motor to ensure it is getting pack voltage in FWD? (by the way, wheel turns very slowly in FWD and REVERSE.

I am stumped on this one...

[scottyb]

One wheel turns = okay.
You can stop it = okay.
If pack voltage is not dropping when you try to go on the ground and controller is powering up and dissipating voltage at B- & M- the controller is okay.
Maybe a motor brush issue?

[dschron]

Thanks scottyb

Whats the easiest way to check pack voltage when trying to go on ground? Just a meter on batteries and step on throttle?

also, you stated "controller is powering up and dissipating voltage at B- & M- the controller is okay". How do I check that?

(seriously, I work on H60 helicopters, you'd think I could figure this out!)

By the way, love the digital battery meter you have. Thinking about getting one for my precedent. Do you have to get the plate with the key switch and meter or can ya just get the meter and plate? Does it stay powered up constantly and drain the batteries when sitting?

Thanks

[dschron]

Ok so pack voltage is 50.3. On ground trying to drive drops to 49.6...doesn't seem significant. B- to M- is 49. When I press pedal, drops to 44.

I also disconnected the main leads off of my precedent battery pack, hooked a set of jumper cables to its pack and ran the other side of the cables to this carts red and black, same result. I am sure the batteries in my precedent are good, they are only about a year old and drive my cart just fine.

Brush issue?