2001 EZGO(PDS) goes 0-7mph or 0-24mph after stopping

[Iamicer]

Good Morning BGW: Hoping this finds you all well and healthy. Thank you for taking time to listen, and help me and others with their buggies.

Troubleshooting a 2001 EZGO TXT PDS buggy. Current symptoms (I say current because we have had issues described in prior posts, that have evolved 3 times to the malfunction we have today) are, when the buggy is stopped, pressing the go-pedal, you will either get to go 0 to 7 mph, or 0 to 24 mph.

So for instance, first ride of the day, your speed may be 0-7 mph, or it may be 0-24 mph. First time you come to a complete stop, so the buggy is not rolling, you will switch to the other speed. And if you are in the 0-7 speed, it will try to keep you there. In order to go back to the 0-24 speed, the more normal speed for the buggy, you need to stop again, and hope it returns to normal speed. It seems to help accomplish this, if you switch to N, then F again. I feel like I have more success getting it to go normal speed, if I go from F-N-R, back up a few feet, and even more, turn 90 degrees, then go forward. Family says not necessarily.

In diagnostic mode: Fault code is 3-2. I have tried three different solenoids,
and this does not change anything

Controller: CurtisPMC
Batteries: Duracell GC2, one year old
Reference voltage: 38.5v

Since buggy runs, tho erratically, I am not sure if the ESC(PDS) troubleshooting algorithms apply, but at step 9, voltage between B- and controller side of solenoid, the voltage drops by over 2v, which is outside the 0.4-0.8v range, indicating replace controller.

I am suspicious about the speed sensor, as now the roll-away feature is not functioning, and there is no resistance when I push the cart manually, and there does not appear to be electronic braking like before.

The magnet appears intact, but I do not know how to test the speed sensor, unless I remove the magnet, try to spin it with a speed drill, and test the sensor with a voltmeter somehow for continuity and output.

Would be enormously grateful and indebted if anyone can help with my frustration. Thank you so much for reading, listening, and helping. God Bless.


"Darn it Jim, I am I doctor, not a golf cart technician!"

[kgsc]

Sounds like it is going into limp mode but it usually would be beeping.. Look at the wires going from the controller to the sensor near the back of the battery box. That is a chafing point

[JohnnieB]

Since the cart has a stock PDS controller, the max motor RPM is about 4400 RPM, which is about 19 MPH on stock height (18") tires, but you mentioned it'll do 24 MPH, so it must have 23" tall tires on it and a stock controllers don't last very long turning tall tires.

Sounds like the "sonic" weld on the red wire from the solenoid's battery side large terminal to the beeper and J1 Pin-5, is intermittent. Or at least that would explain both the 3-2 error code and the higher than expected voltage drop across the precharge resistor.

Follow the red wire from J1 Pin-5 into the wiring harness, it will split a few inches inside the bundle. Replace the sonic weld split with a solder joint or a good splitter.


As for the walkaway safety not kicking in, the cart might not be moving fast enough. Normally it kicks in at 2MPH, but with the tall tires it would have to be 3 mph, or so, which is about walking speed.

To check speed sensor, place your DVM's black test lead on J5 Pin-1 (Black wire) and red test least on J5 Pin-2 (white wire). Push cart (or drive it) and you should read some voltage, the voltage will get higher as cart goes faster. It is a pulse train, four pulses each time the motor shaft spins once. (OR, if you have an automotive type DVM with a tachometer function, set it to 8 Cylinders and it will read motor RPM directly.)

[Iamicer]

kgsc,

Thank you so kindly for taking time to reply. When I became suspicious of the controller, I inspected the sensor wire bundle from controller to motor, just to be sure it was not damaged, and did not see any damage, and others have mentioned chaffing and shorting where the sensor wire traverses through the wire holders at the motor and back of the battery box.

I will double check this area again.

Also, it does beep when it rolls. If I push it fast enough, it will beep, but there is no resistance, and my understanding was, if it beeps the speed sensor is good, but there is no resistance when I push it on level ground.

I let it roll down a steep grade, and it no longer brakes electronically like it use to, but it does beep as it is rolling.

Likewise, if I am cruising, and turn the key off or switch from F to N, it will continue to roll to a stop naturally, beeping while it does, but does not electronically brake.

Sorry I omitted that, but it does beep.

Again, thank you so kindly for your rapid reply. Million thanx.

[Iamicer]

JohnnieB,

Thank you so very much for your rapid, and informative response.

In my initial post, I stated I was reporting my current symptoms. Our buggy for several years was doing the "suddenly braking and beeping" malfunction described ad nauseam, on this forum, while we were cruising on pavement. At the time, I was new to PDS, and suspected the beeping and electronic braking was a malfunction, but it was very intermittent, would go days, weeks or longer and not do it, or do it several times in one day. Once it stopped, merely pressing the go pedal, and you were rolling again.

To complicate this, I did not know about diagnostic mode, and family hated the reverse buzzer, so I disabled it. Over the past year, the "suddenly stopping" issue worsened, the service manual made it sound like this was solenoid drop out, so I replaced the solenoid (admittedly, sheepishly, with a cheap, non-oem solenoid), and the problem instantly worsened.

After I replaced the solenoid, the buggy ran fine on pavement, but as soon as you left pavement and rode on crush and run, or dirt, hit a chuck hole, divot, speed hump, the buggy would instantly stop completely, and would take working the pedal for a length of time to get it moving again. I'm thinking loose wire or short or bad connection.

At times, the buggy would not move at all, and became non-usable. In my feeble attempt to research and diagnose this issue, I learned about PDS diagnostic mode, re-enabled the backup buzzer, and low and behold it didn't work. Thinking it was a corroded bad buzzer, (we live seaside, exposed to salt air chronically, everything corrodes rapidly), to be sure, I jumped the buzzer with a wire to the battery pack, and it worked.

I checked the red wire for continuity from the controller at J1, pin 5, to the buzzer, and there was none. I then remembered about a year ago, the wire harness from the controller to the dash (key switch, FNR switch, and buzzer) was drooping below the buggy, and I was worried it was going to snag. Inspection revealed the flexible protective tube the wires are housed in, had eroded on the buggy frame where they pass through buggy frame underneath the passenger side, completely transecting the tube, leaving all 7 wires exposed. Two of the wires, the red wire to the buzzer were crimped, and the white wire with yellow stripe to the key switch, had nicks in the insulation, and exposed metal wire. I taped them at that time, and secured them.

When I reconnected the buzzer, and it didn't work, and found no continuity in the red wire, I went back to that spot, and found the red wire broken in two, explaining the lack of continuity to the buzzer. Spliced it back together and buzzer worked. It was at this point the buggy then started doing what it is doing now, going 0-7mph, or 0-24mph, and the roll-away feature not working, which it had up until this time.

Now that I had the buzzer working again, I entered, I tried to enter diagnostic mode. Now, it actually takes six movements from N to R to enter diagnostic mode. That gives me the performance option, then constant beep. If I turn the key switch on, and place FNR in either direction, I get the 3-2 (solenoid fault code). Which I get whether it is under a load of not.

Also I do have the freedom plug installed, but removing it does not change anything.

All of my problems existed when the buggy had stock 18x8.5-8 Carlisle tires on it.

2 years ago, I acquired knobby 21 inch atv tires, which I mounted on the rear only, attempting to increase my speed (wife is speed demon). Those were 2-ply, and quickly wore out as they cruise on asphalt 50% of the time.

I just now mounted 22" Sahara Classic AT tires all around, but the aforementioned erratic speed problems already existed.

I was suspicious about the red wire from the battery side of the Solenoid where it joins with the buzzer wire to the controller, but was hesitant to open that area, because it appeared intact and clean.

Based on your keen assessment, I will do that asap, and test the speed sensor as you suggested.

Your are a brilliant man. Thank you again so kindly. Million Thanx!!!

I will update as soon as I can with my findings.

[Iamicer]

Is the pre-charge resistor "directional", i.e., does it matter which side of the resister is attached to the battery or controller side of the solenoid? There are no markings on the resistor to indicate positioning.

[JohnnieB]

Originally Posted by Iamicer

Is the pre-charge resistor "directional", i.e., does it matter which side of the resister is attached to the battery or controller side of the solenoid? There are no markings on the resistor to indicate positioning.

The pre-charge resistor is not polarized.

If the better half is a speed demon, replace the stock controller (Curtis 1206MX) with an Alltrax XCT48400-PDS and the solenoid with a MZJ400 or other solenoid that will operate at 36V, 42V or 48V. Then the next time you replace the batteries go to 42V (7x6V) or 48V (6x8V or 8x6V) and get the appropriate battery charger for that voltage.

The XCT is user programmable and you can up the max RPM setting up to 6500RPM, which is about 34 MPH on 22" tall tires and far too fast for a narrow track, short wheel base, top heavy cart with two wheel mechanical drum brakes. Might have to go to 48V to get 6500RPM with 22" tires due to 18% torque loss cause by the taller than stock tires.

That torque loss may also be why you aren't feeling much regen braking. But with the XCT controller, you can up the max regen amps and the XCT uses RPM data to up the field amps at lower RPM making the regen braking more effective as cart slows. (Stock controller shut off regen at about 8MPPH on stock height tires, or about 10MPH on 22" tires.


Also, about the tires. If they are the low pressure type (<10PSI max pressure) they are amp hogs and knock off several MPH on the top end speed. Aggressive tread patterns also take more oomph to turn, but not as bad a low pressure.

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A PDS cart does a crash stop (Max regen braking and rapid beeping) whenever the voltage is lost on any of the red highlighted wire on the attached schematic. Only takes a momentary voltage loss to trigger, so a loose connection anywhere can cause it.

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You have to cycle Run/Tow switch to change PDS modes.

[Iamicer]

JohnnieB,

Again wanted to take this opportunity to thank you for all your help and expertise.

Work jumped on me past several days, which precluded my chance to try remedies you offered, hope to tonight or tomorrow.

Have contemplated upgrade to 48v, as have a 48v club car (called a "Lynx" by club car) that would run 1-2 days on a charge, and range 25+miles, but that car lost power and was never able to get it returned to service. This 36v EZGO PDS I am having problems with, with brand new batteries gives us maybe 45 minutes of use, and 5-6 miles before it starts asking for a receptacle.

Have also been looking at other options, i.e. Intimidator EV, HuntVe, Massimo Buck 50 or 60 EV, and am impressed by the eNVy Neighborhood vehicle. Also, despite my convictions not to go gas, have started to entertain idea of Yamaha QuieTech EFI. But $$$$ and lack of experience with any of these give me trepidation.

Your expert recommendations give me a plan for upgrade to 48v and will guide me in that endeavor, and I can't thank you enough.

[Iamicer]

[QUOTE=JohnnieB;1820190]The pre-charge resistor is not polarized.

UPDATE: I wanted to perform tests multiple times on different days to confirm findings

Per JohnnieB's recommendations:

1) I removed the sonic weld that connects J1 Pin 5 to the battery side of solenoid and the buzzer. In lieu of restructuring that joint in the control harness, as it was, via solder or wire combiner, I added a ring terminal to the short pigtail coming from J1 Pin 5, and attached directly to the battery side of solenoid, which mirrors the blue wire from J1 Pin 6 to solenoid (-), and yellow wire from J1 Pin 7 to solenoid (+), then spliced the original pigtail from the solenoid to the red wire in the control harness to the buzzer.

Now if there is a reason this needs to be a three way connection in the harness, I will redo that.

This corrected the higher than expected voltage drop I was getting across the pre-charge resister, back into the normal range at 0.7v (normal range .4v-.8v), however did not correct my issue of the vehicle going 0-7mph or 0-24mph after stopping.

2) Turning my attention to the speed sensor, I removed the ESC environmental cover, and placed DVM probes on the J5 black and white pin terminals. I get 5v here, vehicle stopped, key off, FNR in N. Driving the vehicles drops the voltage to 2.7v +/- 0.5v.

I intended to check this variable in both the 0-7mph state, and the 0-24mph state, but while performing this test, the buggy operates normally, and goes 0-24mph +. Also, the regen braking, rapid beeping, and roll-away feature resumes working normally.

3) Since the buggy was now operating normally with the ESC cover removed, I became suspicious, about the cover being the issue. I replaced the cover, and indeed, the buggy resumes the issue of going 0-7mph or 0-24mph and changing to the other speed after the vehicle is stopped. Also, regen braking, and roll-away stops working.

I removed the cover, and lifted the tow switch wires into a position I envisioned the wire bundle to be in when the cover is properly installed, and this reproduced my symptoms, speed varying after stopping, regen braking not working, and no roll-away function. Straightening the wires out, resumes complete normal buggy function including speed, regen braking and roll-away function.

4) If I push gently on the bottom of the J3 connector, or bend the wires up slightly, putting tension on the connector, my symptoms are reproduced. Relieving the tension on the connector resumes normal function.

The pins inside the J3 port/connector in the controller appear intact, and normal. The connector portion attached to the wires from the tow switch also generally appear normal, without signs of wear, breakage or burn. There is continuity from the switch to all four terminals in the J3 connector. Since applying slight pressure on the bottom of the connector reproduces the symptoms, I am inclined to rule out the wires themselves as the issue.

I am just not sure how to correct the issue, as the symptoms occur when the ESC environmental cover is installed. Could the J3 connector be soldered to an IC inside the controller, and be loose? So when pressure is applied from the outside on the connector, the circuit inside the controller is affected?

Any help or suggestion would be greatly appreciated. Thanking you again, and wishing all a pleasant day.