RXV Curtis Overcurrent mystery

[nickdalzell1]

Hi everyone, got a mystery I need help solving

We were tearing down a later model RXV 48V (with the new Curtis controller) and when we had it down to the frame (we are putting custom body on it) it now won't move half the time. sometimes it does, sometimes it doesn't. even putting it in TOW and neutral won't do anything (we have to use the little red connectors under the controller cover to unlock the brake so it will roll when this happens)

The handheld, 1311 Programmer, shows two codes, Controller Overcurrent, and the active code is EM Brake Driver OC.

the odd thing is, since you can unlock the brake using the red connectors, the brake is obviously working. before I throw a new controller at it, i'd like some advice.

[BobBoyce]

Originally Posted by nickdalzell1

Hi everyone, got a mystery I need help solving

We were tearing down a later model RXV 48V (with the new Curtis controller) and when we had it down to the frame (we are putting custom body on it) it now won't move half the time. sometimes it does, sometimes it doesn't. even putting it in TOW and neutral won't do anything (we have to use the little red connectors under the controller cover to unlock the brake so it will roll when this happens)

The handheld, 1311 Programmer, shows two codes, Controller Overcurrent, and the active code is EM Brake Driver OC.

the odd thing is, since you can unlock the brake using the red connectors, the brake is obviously working. before I throw a new controller at it, i'd like some advice.

I've seen this before, and for your controllers sake do not attempt to operate it again until you replace the motor brake!

The motor brake can be bad and still operate. The cause for the EM Brake Driver OC is a short in the motor brake coil that is reducing the impedance and making it draw too much current. When you jumper it using the bypass plug/socket method, there is no current sensor, so you don't get an error when it draws too much power. When it is connected normally, the brake is activated by the Motor Brake Driver FET, which does have a current limit, of 3 Amps. Continuing to operate it will cause that FET to short out, then the cart will fail to operate totally and the brake will unlock any time the key is on.

Been there, done that. I had a brand new defective motor brake shipped to me and it took out my controller. Thank goodness I know Curtis controllers so well. It still took a while to get the part. Here is a photo of the FET. It is a surface mount FET and the back of it is soldered to a board pad that is connected to a heat sink plane. To remove it with a hot gas reflow station requires grinding the plastic away in order to get direct thermal transfer to the FET heat sink tab. Not an easy task, even when you are experienced at SMD replacement.

Bob

[nickdalzell1]

Thanks! I'll keep that in mind for the next time this happens.

All the info I've found just searching Google seems to point to the older Danhauer style, not the newer Curtis. We just started getting the Curtis style in our shop and we already had three come in with fried controllers (the last mystery was one showing 'Encoder fault' even after we tried three speed sensors--we ended up having to replace the motor and controller because the original motor fried a new controller the first time! customer pushed it while in RUN and didn't tell us--probably took everything out)

Up till now the only Curtis controllers I've diagnosed have been on the Precedent and IQ Club Car DS, and TXT 48V. the Curtis RXVs are more, shall we say, 'picky' about everything and have far more codes to throw. it's the random ones having me chasing ghosts that throw me for a loop. One of the other of the three that needed controllers had one giving a 'Main Welded' code despite having a new solenoid. Ended up being the controller.

[BobBoyce]

Originally Posted by nickdalzell1

Thanks! I'll keep that in mind for the next time this happens.

All the info I've found just searching Google seems to point to the older Danhauer style, not the newer Curtis. We just started getting the Curtis style in our shop and we already had three come in with fried controllers (the last mystery was one showing 'Encoder fault' even after we tried three speed sensors--we ended up having to replace the motor and controller because the original motor fried a new controller the first time! customer pushed it while in RUN and didn't tell us--probably took everything out)

Up till now the only Curtis controllers I've diagnosed have been on the Precedent and IQ Club Car DS, and TXT 48V. the Curtis RXVs are more, shall we say, 'picky' about everything and have far more codes to throw. it's the random ones having me chasing ghosts that throw me for a loop. One of the other of the three that needed controllers had one giving a 'Main Welded' code despite having a new solenoid. Ended up being the controller.

A lot of quirky controller issues may not be not hardware related, but can be caused by a corruption of controller memory. This seems to be more common with the less expensive golf cart series of controllers due to the more limited memory maps and processing power of the microcontrollers used. They are also much more numerous in the field than the number of full EV controllers in use.

I actually prefer the Curtis controllers for performing diagnostics, basically because it's all I've worked with in my business, other than the electrohydraulic controllers I designed. That seems like a lifetime ago now.

Bob