97 DCS Runs half speed

[Dwood850]

I have a 1997 EZGO DCS, it runs 8mph in both forward and reverse. So thinking it is running half speed. Pack voltage is 38v, when I drive the cart it drops to 36.5v. Replaced all cables with 4g welding wire. All wires are correct according to the wiring diagram. Ran tests from DCS troubling shooting sticky. ITS and controller all have proper voltage and solenoid clicks. Only anomaly is before solenoid clicks have 38v on both big terminals in run whether key is on or off. I removed the resistor when testing the solenoid. Replaced solenoid and have the same problem. When in tow the solenoid is acting normal with no voltage on one side and pack voltage on the other. with resistor in place on solenoid in tow I have pack voltage on battery side and 3 volts less on controller side. In run I have pack voltage on both sides with resistor in place. Never experienced this problem before . Any help would be appreciated. Not sure what to test next.

[biphase]

Check the orange wire in pin 4 of the ten pin connector on the controller. 36 volts on the orange wire causes the cart to run half speed. Pin 4 should be 36 volts in reverse only and zero volts in forward. If it is 36 volts in both FWD and REV, the cart will run half speed all the time. Also, check that you have 36 volts on both pins 9 (red) and 10 (red/yellow).

[Dwood850]

Thanks for the reply, we have checked pin 4 the orange wire at the controller
In forward and pedal pressed result was 0 volts. Pack voltage when in reverse and pedal pressed. Pins 9 and 10 check out at pack voltage

[biphase]

Does the solenoid click every time you step on the pedal or only once when you go from tow to run?

[Dwood850]

The solenoid only clicks when the pedal is pressed , does not click when tow/run switch is turned to run. It doesn’t click when the key is turned on or off. It clicks when the pedal is pressed and then disengages after pedal up. Very strange
I am very confused by this, have no idea how it could be transferring the power without being activated . Thanks again for your help

[biphase]

The DCS controller has an internal precharge circuit which enables the internal capacitors to precharge through one of the terminals on the 10 pin plug as soon as you switch to run so it is not unusual to see near pack voltage on the output side of the solenoid even before you step on the pedal.

It would be interesting to see if the controller is fully turning on when you are at max throttle. Use your volt meter to make the following measurement:

1. Put the black lead on B-
2. Put the red lead on the A2 blade on the controller.

The voltage on the A2 blade should start out at about 36 volts and DECREASE all the way to zero volts at max throttle. The voltage should go lower as the cart goes faster. If the voltage never gets to zero, the controller is not turning on all the way.

[Dwood850]

Ok, performed the controller test . Black lead on B- of battery pack and red lead on A2 blade of controller. Pressed pedal to the floor and got voltage drop of only a couple of volts 37.5 to 35.7 . Also did the test of controller Black lead B- and red lead on A 1, pressed pedal and voltage went from 37.5 all the way to zero.

[biphase]

Yeah, OK looks like I had A1 and A2 mixed up but A1 went all the way to zero indicating that the controller is turning on 100% and yet the cart runs only about half speed. That would seem to indicate an issue with the motor or some mechanical issue with bearings or dragging brakes.

[Dwood850]

Thank you for all your help, I have the brake cables disconnected and the wheels spin freely. I thought it was the motor brushes and swapped motors , I had one extra sepex motor , (small field wires) installed it the other day , same issue
Half speed…I am still trying to figure out the pack voltage on controller side of solenoid without activation. I think it has something to do with my issue , but I don’t really know, really appreciate your time and advice. Thanks again

[biphase]

The DCS controller has an internal precharge circuit which enables the internal capacitors to precharge through one of the terminals on the 10 pin plug as soon as you switch to run so it is not unusual to see near pack voltage on the output side of the solenoid even before you step on the pedal.