2001 DS with intermittent speed surge

[BlackTalon]

48 volt cart was experiencing a speed surge from high to low back to high with the peddle pressed to the floor. Checked the batteries and found a dead cell replaced all the batteries new Trojans charge them over night. Ran the cart the next day when well for about 10 minutes then the surge came back for about a mile then no more surging for another 2 miles stopped for the night. Charged again over night and ran it again this morning surge was back. Search through the threads found some carts of the same year with a similar problem but these had an MCOR and mine has a MULTI-STEP POTENTIOMETER. So I'm not sure where to start diagnosing the issue any help would be greatly appreciated.

Cart serial number AA107-990506.
I'm attaching a diagram from the manual that closely resembles the setup in the cart.

[NoleFan4Ever]

Open it up and check the micro-switch and more importantly the contact pads and wiper arm. They could be worn or out of alignment and that just causes what you describe.

[BlackTalon]

Thank you, I'll give that a try and see what happens.

[BlackTalon]

Took apart the wiper arm switch and measured ohms at each contact using three prong plug's purple and yellow wires:
Position 6 was 5720 ohms, 5 - 4650, 4 - 3629, 3 - 2634, 2 - 1580 & 1 - 898. Removed burnish from contact pads to bright copper and wire arm pad just the burnish. Rechecked ohms at each pad came out the same as above. Adjust throttle linkage to land right on pad 6 when peddle pressed to floor, no peddle when back to the bump stop at the base of the switch. Took the back cover off to expose the pad registers the one on 6 exhibited some green corrosion on the wires and at the resister itself. Check the ohms read 10730 the color coding is gone so don't know what it really should read. When for test run no hesitation occurred for 3 miles passed radar check at 13 mph (3.1 HP motor) thought the problem was fixed. This morning went for another test the surging was back.
Any other ideas what else could be causing the problem?

[NoleFan4Ever]

What is the DVM reading (or use a hand held if need be) during the entire period when this occurs?

[Tom47]

Another thing to look at is the motor. If original, there is a good possibility that one or more of the brushes are not making good contact with the armature for various reasons.

My original 3.1 HP motor had one brush that burned through the brush holder. It made contact with the armature most of the time but then would cut out for several seconds, then go back to normal operation.

I replaced and checked everything else in the process, and although I am happy with the final results, I could have saved a lot of frustration by checking the motor first. It's just that when it ran, it ran pretty good so I didn't suspect the motor until the end when the brush finally came completely out of the holder and it died. Luckily was just pulling into my driveway.

[NoleFan4Ever]

Originally Posted by Tom47

Another thing to look at is the motor. If original, there is a good possibility that one or more of the brushes are not making good contact with the armature for various reasons.
-snip-

Good point.

[Raystar57]

Originally Posted by Tom47

Another thing to look at is the motor. If original, there is a good possibility that one or more of the brushes are not making good contact with the armature for various reasons.

My original 3.1 HP motor had one brush that burned through the brush holder. It made contact with the armature most of the time but then would cut out for several seconds, then go back to normal operation.

I replaced and checked everything else in the process, and although I am happy with the final results, I could have saved a lot of frustration by checking the motor first. It's just that when it ran, it ran pretty good so I didn't suspect the motor until the end when the brush finally came completely out of the holder and it died. Luckily was just pulling into my driveway.

I Agree,
I would pull the motor and check it and clean.
This is the GE motor with magnet on the end of the armature shaft.
This is the used brush set cleaned up with brushes parked ready for install.
Also clean up the commutator as well as you can.
Inspect the bearing for excessive play and replace if necessary.
Post some some pics so we can see how it looks.

[BlackTalon]

All good points, ran a motor voltage test this morning, checked batteries first showing 50.8 volts. Put voltage meter probes on Motor posts A1 and A2 at the startup registered about 3.8 volts pressed pedal slowly to the floor voltage increased as it stepped through pads 1 to 6 surging started voltage was rapidly fluctuating between 30 to 44 volts for 1/4 mile then settled around 34 volts for the remainder of test drive. Working backward from motor to control going to test input/output voltage from it. Later today will post results.

[Raystar57]

I think the ohm values look good.
What I would also check is the multi pin connector into the controller.
The resistance values into the controller from the v-glide go into that.
If there is resistance due to crud/corrosion the values could become varying.
Pull it out and clean it real good with contact cleaner and see if that helps.