2012 rxv wont move

[Tony4517]

I have a 2012 rxv with curtis controller. It is a campground cruiser. I was driving and stopped for a minute. Went to take back off and it wouldnt move. Batteries were charged and reading 50.8 volts. I tried tow mode and nothing, still wouldn't move. I followed instructions under tow switch cover and when i swapped plugs the brake disengaged and i pushed it back to my campsite. I swapped the plugs back and nothing. The solenoid clicks, i can also hear the click at the motor during precheck when key is turned on. Reverse buzzer works fine. I pulled the mat and the brake and gas pedal switches seem to be working fine. I have just over 48 volts at the motor brake plug. The motor brake is reading at 14ohms. Could the motor brake be my issue? Any help would be greatly aprreciated. Thanks

[BobBoyce]

Originally Posted by Tony4517

I have a 2012 rxv with curtis controller. It is a campground cruiser. I was driving and stopped for a minute. Went to take back off and it wouldnt move. Batteries were charged and reading 50.8 volts. I tried tow mode and nothing, still wouldn't move. I followed instructions under tow switch cover and when i swapped plugs the brake disengaged and i pushed it back to my campsite. I swapped the plugs back and nothing. The solenoid clicks, i can also hear the click at the motor during precheck when key is turned on. Reverse buzzer works fine. I pulled the mat and the brake and gas pedal switches seem to be working fine. I have just over 48 volts at the motor brake plug. The motor brake is reading at 14ohms. Could the motor brake be my issue? Any help would be greatly aprreciated. Thanks

Yes, 14 ohms at the motor brake can burn out the Motor Brake control FET really quick. It's drawing twice the current, which the FET cannot supply without damage. That is why Tow mode will not release the brake, but the brake bypass procedure does release it. I had the exact same thing happen to my 2012 RXV. I had to replace the Motor Brake control FET. It was a royal pain to change, but that fixed my controller. You will need a new Motor Brake as well. Here is where I've bought them from.

https://www.ebay.com/itm/301992451277

Bob

[Tony4517]

Hi Bob, excuse my ignorance but replacing the Motor Brake control FET is inside the controller correct? Could the fact I have oversized tires on it contributed to this? Its never really drove faster than 12 to 15 mph since im in a campground.

[cgtech]

I'm thinking motor brake too. The other scary part may not be your problem. Try a brake first.
The "because I have bigger tires" part does add up, because bigger tires add load to that brake if the single instance of "I had to mash the brake to the floor" happened. That's how it goes with Rxv and big tires. I have seen motor brakes discs shattered into many pieces before from one "panic stop" at high speed (same kind of load as "big tires" would apply). Im Not saying "as long as it's not blown into pieces your ok" at all. Rxv is very picky a out it's brake, as that's all it has for "last resort" when all else fails.

[BobBoyce]

Originally Posted by Tony4517

Hi Bob, excuse my ignorance but replacing the Motor Brake control FET is inside the controller correct? Could the fact I have oversized tires on it contributed to this? Its never really drove faster than 12 to 15 mph since im in a campground.

Yes, the FET is inside of the controller, and is not something the average person can change. It is a surface mount device, and requires special equipment to remove and reinstall. But a motor brake with a 14 ohm coil is definitely bad, so replace it! cgtech is correct, large tires will overstress the motor brake and reduce braking effectiveness during regenerative braking, which is the ONLY brakes that the RXV has.

Before I reprogrammed the stock Curtis controller in my 2012 RXV, it would drive at 27 to 28 MPH with stock tires. I turned it down to 25 MPH, and was happy with it. Until I wrecked it and totalled it. I now have a 2008 RXV (flood cart) Shuttle 2+2 with a lithium pack, 20.38" tires (no lift kit), and a reprogrammed Curtis 235 Amp controller. It was set for 25 MPH, now it does 30 MPH. The RXV is a complex cart, with a very sophisticated controller. It shuts down when there is a problem... So listen to what it is telling you!

The first step is to replace that motor brake! Then go from there. If that fixes it, then you are good to go. If not, we go on from there. But if the FET is not yet blown and you continue to operate it with that 14 ohm motor brake, it WILL take out the motor brake FET. It has to, because the FET can only handle a 3 Amp load and the motor brake fuse is a 7.5 Amp fuse, 2.5 times the rating of the FET. The fuse must still be good because when you bypassed, it unlocked...

Bob

[Notocer]

Bob can you piggy back the fet?

[BobBoyce]

Originally Posted by Notocer

Bob can you piggy back the fet?

Unfortunately not. It is a SMD (Surface Mount Device) that is soldered onto a heat sink plane on its back side. The SMD removal requires hundreds of watts of heat to overcome the thermal dissipation of the heat sink pad enough to remove the device. That requires more than the average SMD rework tooling. To apply the replacement SMD requires quick application of very high heat, then rapid cooling. Otherwise the heat required to bond the new FET would destroy it. Here is a photo of the motor brake FET in the RXV controller that I repaired.

Bob

[Notocer]

Thanks Bob.

[Tony4517]

Update I found an authorized EZGO dealer about an hour away drove out there today and took my old motor brake with me. They had a cart torn apart and plugged in my motor brake and found out that it did not unlock during their test. They suggested I buy the heavy duty option of the motor brake since it dissipates heat better than the regular one. I installed the new motor break in the cart and it is working perfect. It is actually much quieter during the pretest compared to before. Im glad that was the problem. Thank you everyone for your help. It is appreciated.

[BobBoyce]

Originally Posted by Tony4517

Update I found an authorized EZGO dealer about an hour away drove out there today and took my old motor brake with me. They had a cart torn apart and plugged in my motor brake and found out that it did not unlock during their test. They suggested I buy the heavy duty option of the motor brake since it dissipates heat better than the regular one. I installed the new motor break in the cart and it is working perfect. It is actually much quieter during the pretest compared to before. Im glad that was the problem. Thank you everyone for your help. It is appreciated.

Wait! Do not use the Heavy Duty motor brake!!!!!!

That Heavy Duty motor brake will damage your controller if left on there long. It draws more power than the OEM motor brake! Buy that OEM one I linked earlier if the dealer you bought from does not carry the OEM one. I don't think you'll beat the price either.

Bob