Cart won't reverse and stuck at low speed

[skabeds]

Hello everyone. I'm new here (first post) and I've been trying to figure out a problem with a cart that I've decided to try and fix here at work. The initial issue was that the cart wouldn't reverse. However, going forward wasn't a problem. I've also noticed as I was troubleshooting the cart that full power wasn't getting to the wheels. I'll explain that when I get through what I've done to troubleshoot. Everything I've done and researched is pointing me to a faulty controller but I just wanted some opinions to make sure that is the case before I go ahead and ask my company to order a $700 component. So here are the details:

Cart:
2003 TXT Standard (PDS)
Electric 36 V
Ser #: 2001472
Battery Pack Voltage: 35.49 V (one battery is about a volt shy than the rest)

Tests and Results:
So for the most part I've used the testing steps found on another web site. It's basically the same testing steps found in the stickys of this forum with one added step (which is the step that made me realize that I wasn't getting full power to the wheels). Battery pack voltage test results I gave above. Solenoid testing yielded 35.49 V and 33.13 V on the battery and controller sides of the solenoid respectively. So the solenoid and resistor are both in working condition. For reassurance I double checked the resistor by itself. Plus I didn't think the solenoid was an issue as it activated fine when the cart was set in the forward direction. However, there is NO activation when set in the reverse direction.
Now the final test they listed tested the voltage between the B+ and the M (although I assumed it was A1 since my cart doesn't have a M) terminal posts and what happens when the accelerator is pressed. This resulted in 17.50 V and not full voltage between B+ and M when the accelerator was fully pressed as it stated I should have.

And that's it. I know it was lengthy but I wanted to make sure i got all the info to you guys to make a proper opinion. Overall, nothing works in reverse- motor, solenoid, etc. - aside from the reverse alarm and I am not getting full voltage to the motor in forward. Am I right in thinking it’s the controller?

Thanks in advance, Sean

[scottyb]

Originally Posted by skabeds

Hello everyone. I'm new here (first post) and I've been trying to figure out a problem with a cart that I've decided to try and fix here at work. The initial issue was that the cart wouldn't reverse. However, going forward wasn't a problem. I've also noticed as I was troubleshooting the cart that full power wasn't getting to the wheels. I'll explain that when I get through what I've done to troubleshoot. Everything I've done and researched is pointing me to a faulty controller but I just wanted some opinions to make sure that is the case before I go ahead and ask my company to order a $700 component. So here are the details:

Cart:
2003 TXT Standard (PDS)
Electric 36 V
Ser #: 2001472
Battery Pack Voltage: 35.49 V (one battery is about a volt shy than the rest)

Tests and Results:
So for the most part I've used the testing steps found on another web site. It's basically the same testing steps found in the stickys of this forum with one added step (which is the step that made me realize that I wasn't getting full power to the wheels). Battery pack voltage test results I gave above. Solenoid testing yielded 35.49 V and 33.13 V on the battery and controller sides of the solenoid respectively. So the solenoid and resistor are both in working condition. For reassurance I double checked the resistor by itself. Plus I didn't think the solenoid was an issue as it activated fine when the cart was set in the forward direction. However, there is NO activation when set in the reverse direction.
Now the final test they listed tested the voltage between the B+ and the M (although I assumed it was A1 since my cart doesn't have a M) terminal posts and what happens when the accelerator is pressed. This resulted in 17.50 V and not full voltage between B+ and M when the accelerator was fully pressed as it stated I should have.

And that's it. I know it was lengthy but I wanted to make sure i got all the info to you guys to make a proper opinion. Overall, nothing works in reverse- motor, solenoid, etc. - aside from the reverse alarm and I am not getting full voltage to the motor in forward. Am I right in thinking it’s the controller?

Thanks in advance, Sean

You can't evaluate performance with a bad battery one even a bad cell in 1 battery so forget the speed issue until you get a new control and batteries.

[Sir Nuke]

YEP, what scotty said......the fact that your batteries are at 35.49v.....they are DEAD.

that is if that is the voltage after they have been fully charged and rested for 12 hrs, which should be in the neighborhood of 38.3v.

[skabeds]

So aside from the power/speed issues the cause of the reverse issue IS the controller?

[radioman]

Originally Posted by skabeds

So aside from the power/speed issues the cause of the reverse issue IS the controller?

Your batteries are almost dead, not completely dead. Weak batteries is the speed issue but not the cause of not backing since it moves forward on the same weak batteries. Logical troubleshooting procedures would point to the controller. However troubleshooting golf carts don't always follow logic. The M lead is the output of the controller voltage is controlled B- output so it would not normally read full battery pack voltage referenced to B+. This is how the speed is controlled.

[JohnnieB]

Originally Posted by skabeds

So aside from the power/speed issues the cause of the reverse issue IS the controller?

Probably.

The difference in Forward and Reverse in a PDS cart is the direction the current flows through the motor's field windings and the direction the current flows through the field windings is controlled by the controller.

Since the cart moves forward (slowly, but it moves), it should move in reverse unless the controller is bad, or the controller is not being told to go into the reverse mode.

If the beeper is sounding when the direction selector is in R, than the controller is being told to go into reverse. Therefore the controller is bad.

When measuring the voltage between the controller's A1 terminal and the B+ terminal, you should have about zero volts when the pedal is pushed just far enough for the solenoid to click and it should measure FULL battery pack voltage when the pedal is on the floor. Full battery pack voltage means whatever the pack voltage is when the pedal is on the floor.

Personally, I prefer to start by measuring between the A1 (or M- or other type controllers) and the B- terminals since that is directly across the the control element (a dozen or so MOSFETs in parallel) in the controller. That should start at FULL pack voltage when the solenoid first clicks and decrease to near zero as pedal is pushed to floor. It is easier to troubleshoot that way since you are looking for the pack voltage rather than the absence of it.