02' Club Car Full Speed or Nothing

[Astrostrat89]

I have a 48v 2002 Club Car DS that we've had for about 4 years. Honestly have had lots of problems with it. It's pretty much sunk-cost-bias at this point but may be close to giving up on it. Everything seems to be pointed to the controller with the current issue, but as a last ditch effort I thought I try and get some advise.

The current issue is that in either forward or reverse the cart will most likely either go full speed only or not go at all. When it doesn't go the solenoid does not engage. When it does go full speed it starts at the top of the pedal motion. If I continue down on the pedal it stops but the solenoid is still engaged until it clicks off. Disconnecting the speed sensor doesn't seem to impact this behavior.

This issue has been happening off and on since I got it out for the season in March. Sometimes it seems to work fine for up to a week at a time. Because it's been intermittent I've been on a wild goose chase replacing the following...

Just this year...
MCOR - actually on my 3rd one. Just replaced with the new style conversion today.
Solenoid and resistor
Tow Switch
Key Switch and buzzer
Charging port - see more info below on why.

In the past...
Stock Speed sensor
Controller - I messed up in 2017 and fried the controller when cleaning terminals. I got it replaced with a repaired core trade in type deal.

I am fairly handy (at least follow instructions) and have been using a Controller Troubleshooting guide to measure voltages. Some of the readings are a little suspect but are so close to what they should be I'm not sure if they are withing tolerances or not.
Misc Info...
- Pack Batteries are from 2016, and charge fine , they have strong voltage readings.
- I have measured the speed sensor with a volt meter turning the wheel slowly.
- The reason I had to replace the charging port was because the red wire going to pos pack got pinched between the seat bracket and frame. Essentially sending pack voltage to the frame. I have a feeling this has fried the controller (again, sigh)
- I can measure 38-40v from Neg Pack to the frame now but very low current, not enough to light a test light. I have tested continuity from every thing I can think of to the frame but nothing.
- I have added a 12v stepdown with a light. Disconnecting it has no effect.

FWIW here are some of the reading I recorded before this last MCOR replacement...
Pack Voltage 51.2
Pin 7 49.4
pin 6 51.1
pin 12 50.7
pin 1 4.5
pin 1 with mcor removed 4.9
pin 2 up to down 0.3 4.3
pin 3 .4
pin 15 15.52


Thanks for any help provided.

[WalterM6]

Just a SWAG but I'm thinking that when you replaced your MCOR for the third time you didn't install it correctly. Recheck the wiring. You probably have it wired as a 0-5K instead of a 5K-0 ohm MCOR. Worth checking out. Be sure to take plenty of pictures and make lots of drawings before starting any work.

[NoleFan4Ever]

I do not ~believe that can happen Walt. The connectors are keyed to only go one way and the rheostat/potentiometer is set up along with a 5 volt circuit loop back to the controller.

If I am overlooking something let me know. I have to face I am not omnipotent! Lol!

[NoleFan4Ever]

Originally Posted by Astrostrat89

-snip-

The current issue is that in either forward or reverse the cart will most likely either go full speed only or not go at all. When it doesn't go the solenoid does not engage. When it does go full speed it starts at the top of the pedal motion. If I continue down on the pedal it stops but the solenoid is still engaged until it clicks off. Disconnecting the speed sensor doesn't seem to impact this behavior.

Try this: Unplug the two pin connector from the MCOR and jump out the connector with a paper clip or a small piece of wire. It will be a blue wire and green wire connector. If it runs with the jumper in place, your MCOR has failed.

If still the same, then with the batteries connected, key switch Off, Tow/Run switch in Run; place the black (–) probe on packs main Negative post and the red (+) probe on the yellow wire at the 3-pin connector near the MCOR. (The reading should be approximately ~0.32vdc to ~0.5vdc with the pedal up). Slowly press the Go Pedal and the readings should increase until it reaches ~4.65vdc or more when the pedal is fully pressed. (Anything less than 4.60vdc and you are not reaching full throttle). If the reading is erratic or jumps all over the place it is a bad MCOR potentiometer.....

If all that checks out, we will test the controller output to the motor.

[Astrostrat89]

Thanks, for the replies. I have not checked the voltages with the newest MCOR in place. But because the issues have not changed between the previous MCOR (Which is only a year old and bench tests ok) and newer one I have pretty ruled the MCOR as the issue out.

I have done the test you are asking for with the jumper on the switch connector. I pretty much get the same behavior sometimes it works sometimes not. I have also taken the voltage readings on the potentiometer. The results were the Pin2 test at the controller. Here is an interesting bit. If I close the switch either by the pedal or jumper I can unplug the potentiometer side of the and plug it back in and so far 100% of the time the wheels will spin and seem to have control over the speed. It seem to be "resetting" some sort of component\variable to make it work.

results of the test
pin 2 up to down 0.3 4.3

I will take new readings with the newest MCOR in place to see if that's changed. I figured the 0.3 4.3v was a little low but again, sometimes the cart just works.

Thanks again.

[Astrostrat89]

I am basically following these procedures for the Curtis 1510a troubleshooting\install guide. (I can't post links yet). Before I started the tests the cart was either going full speed only, or cutting out. During the tests on the jack stands everything seemed normal again. And when I was done the cart is driving normal again (of course). But now that I think about it, every time I go through this testing the cart seems to work for a little while. As stated up to a week at a time. Now I can't get it to fail.

I did not have time to measure the Motor this time, but before I recall that A1 to A2 was just slightly under .3 Ohms. So it may be time to replace the motor brushes?

Here are the rest of the tests.
Pack Voltage 50.5v
pin 5 49.8v
pin 9 - 50.5
pin 8 f- 0
pin 8 r - 50.5
pin 16 f - 0
pin 16 f - 50.5
pin 7 - 0.2v
pin 10 key on 50.5
pin 10 key off - 0
pin 6 up - 0
pin 6 ped down 50.0
pin 12 49.9 pack at 50.3
pin 1 mcor in 4.6
pin 1 mcor unplugged 4.9
pin 2 pedal up 0.3
pin 2 pedal down 4.6
pin 3 0.3
pin 15 - 15v
pin 14 toggles between 0v and 5v as I spin the wheel

Notes\Concerns.
the Pin 7 is the Buzzer, seems like I may have a bad one? I get Pack Voltage on the other side of the buzzer. Continuity test between the controller pin and the buzzer connector seems fine.

Is it ok to get a tiny bit of voltage at Pin 2 and Pin 3? The specs show 0v, but getting 0.3v. Maybe I have a wiring harness issue I've not found yet?

Everything seems to be off just a hair. I'm not sure if that is with in tolerances, or its showing a fundamental problem.
-------------------------------------------------------
ALL TESTS ARE CONDUCTED WITH RUN-TOW/MAINTENANCE SWITCH IN THE RUN POSITION AND WITH A GOOD
BATTERY PACK VOLTAGE MEASUREMENT. ALSO, THE CONNECTOR MUST BE ATTACHED TO THE CONTROLLER
WHEN MAKING THESE CHECKS. YOU WILL NEED TO ‘BACK PROBE’ THE PINS FROM THE WIRE SIDE OF THE
CONNECTOR. USE A PAPERCLIP IF NECESSARY.
Attach voltmeter negative (-) lead to main battery – for the following tests
Use the following sequence when checking individual pins (don’t skip steps). If you find a fault, do not move on
to the next step until the fault is corrected:
 Measure the voltage at the main battery positive post (let’s call it Pack Voltage)
 Pin 5 With charger disconnected, must be greater than 30V (if less than 30V this control will be dead)
- If not, your OBC may be in sleep mode. Put your cart on charge for 1 minute, disconnect then
recheck. If you still do not have more than 30V at this pin, you may have an OBC issue
 Pin 9 Must be equal to Pack Voltage
- If not Pack Voltage, check wiring, Sense Diode (if present), Run-Tow/Maintenance Switch or Fuse
 Pin 8 With F/R Switch in Reverse, must equal 0 volts
- If not 0 volts, check wiring and F/R Switch for a shorted condition
 Pin 8 With F/R Switch in Forward, must equal Pack Voltage
- If not Pack Voltage, check wiring and F/R Switch for an open condition
 Pin 16 With F/R Switch in Forward, must equal 0 volts
- If not 0 volts, check wiring and F/R Switch for a shorted condition
 Pin 16 With F/R Switch in Reverse must equal Pack Voltage
- If not Pack Voltage, check wiring and F/R Switch for an open condition
 Pin 7 Must equal Pack Voltage
- If not Pack Voltage, check wiring and Reverse Alarm for an open condition
 Pin 10 With Key Off, must equal 0 volts
- If not 0 volts, check Key Switch for short condition
 Pin 10 With Key On, must equal Pack Voltage
- If not Pack Voltage, check Key Switch for open condition
 Pin 6 With Pedal Up, must equal 0 volts
- If not 0 volts, check wiring and Pedal Switch for a shorted condition
 Pin 6 With Pedal Down, must equal Pack Voltage
- If not Pack Voltage, check wiring and Pedal Switch for an open condition
 Pin 12 Must equal Pack Voltage
- If not Pack Voltage, check wiring and Main Solenoid Coil for an open condition
 Pin 1 Must equal 5 volts
- If not 5 volts, check wiring and check with MCOR removed – if voltage goes to 5 volts, replace
MCOR
 Pin 2 With Pedal Up, must equal 0 volts
- If not 0 volts, check wiring and MCOR
Continued on next page …
Sheet 4 of 4
77-Club Car Precedent IQ (1510_A) Install Sheet-370 Rev 01 05/03/17
 Pin 2 With Pedal Down, must equal 5 volts
- If not 5 volts, check wiring and MCOR
 Pin 3 Must equal 0 volts
- If not 0 volts, harness and/or harness connector is defective, check wiring
 Pin 15 Must equal 15 volts
- If not 15 volts, check wiring and check with Speed Sensor removed – if voltage goes to 15 volts,
replace Speed Sensor
 Pin 14 While slowly turning the drive wheel, must toggle between 0 volts and 5 volts
- If not toggling, check wiring and if necessary replace Speed Sensor

[NoleFan4Ever]

The biggest issue is that if this is intermittent then the readings cannot be validated unless the issue of not running was present at that same you took these.

[Astrostrat89]

Agreed, but that has been part of the frustration.

One question that would be helpful to have answered, is are the values I am seeing on the MCOR normal? Is it expected to see that tiny bit of voltage on them when it is supposed to be 0? Maybe that points to a voltage leak and a wiring harness issue.

pin 1 mcor in 4.6
pin 1 mcor unplugged 4.9
pin 2 pedal up 0.3
pin 2 pedal down 4.6
pin 3 0.3

[NoleFan4Ever]

Originally Posted by Astrostrat89

Agreed, but that has been part of the frustration.

One question that would be helpful to have answered, is are the values I am seeing on the MCOR normal? Is it expected to see that tiny bit of voltage on them when it is supposed to be 0? Maybe that points to a voltage leak and a wiring harness issue.

pin 1 mcor unplugged 4.9
pin 2 pedal up 0.3
pin 2 pedal down 4.6
pin 3 0.3

Yes they are (See post #4). The most important part is 2 things: The voltage increase is even and not erratic and the the Pedal down is at at least 4.60v or you are not reaching full throttle.

[Sergio]

What is your reading from Controller pin #2 to Pin #3?

That is the important value as that is what the Controller sees.

The controller may be having issues providing the negative on Pin #3 which would cause full speed if the cart is running and a no go situation if You are trying to start.

You can cut the purple/white wire near pin #3 and connect the side from the harness directly to Controller B-