EM Brake Coil Missing

[Tayed]

We have a 2012 EXV in our shop that will not move. Seems to go through the power up sequence but will not move. We are getting 2 constant errors from the Curtis hand held , "#Motor Temp Sensor Fault" and #EM Brake Coil Missing.

We have replaced the EM brake with one from a working cart, and traced most of the wiring. We have also tried replacing the key switch and the Throttle peddle all with no success. Today we swapped the controller from another cart and still getting the exact same error message.

Any help will be appreciated.

[BobBoyce]

First the motor temperature error.

The pre-January 23rd 2012 RXVs used the Danaher controllers. The negative wire of the temperature sensor is bonded to the negative wire of the motor speed encoder, and this bonded pair is bonded to the bonded negative pair from the throttle encode and brake encoder. This quad bonded wire runs to the Danaher controller, pin 4. Check continuity on the motor temperature sensor negative to controller pin 4.

The post-January 23rd 2012 RXVs used the Curtis controller. Those twin bonded pairs are split, with the temperature sensor and motor speed encoder bonded pair running to the Curtis controller, pin 7. The throttle encoder and brake encoder bonded negative pair runs to the Curtis controller, pin 18. Check continuity from the motor temperature sensor negative to the controller pin 7.

Corrosion could have made it into the harness and opened the circuit for the motor temperature sensor.

As for the motor brake open circuit, did you check the resistance of the motor brake coil? It should read between 25 and 28 ohms. If it reads ok, check the connections at the motor brake harness connector, at harness connector #1/#2, and at the Brake Switch near the left rear of the brake pedal assembly. The brake switch is a normally closed circuit until a set brake pedal travel is reached, then it goes open circuit. If that switch fails open, it will give the same response as an open motor brake coil. Brake positive and brake negative both route throught the Run Plug under the cupholder. If that run plug is missing, or any of those wires are broken in that circuit, you'll get the same error.

If you need further help, let me know which controller you have and I'll see if I can post a wiring diagram here for you.

Bob

[Tayed]

Thank you Bob for your response. I will check the cart tomorrow.

[Tayed]

Thank you for your help. I checked the EM brake and it is 26 ohms and the brake will engage and disengage when I switch plug 2 and 3. I do have continuity to the white and black wires on the EM brake.
This is a Curtis controller and I do have a wiring diagram from the"RXV AC Curtis Advanced Troubleshooting guide.
I Checked the wiring on the temp sensor and it checks out ok. It has the tampon style sensor and I am going to try a new one tomorrow. Can I just plug the new sensor into the harness without installing it into the motor just as a test?
Going back to the EM brake issue. I noticed that if I unplug the brake pedal switch that you told me to check the error "EM brake coil missing " goes away? Doesn't make sense since that is a NC switch and it checked ok.

While the Curtis Hand held is in use showing the current errors(in tow mode) I can manually press the brake switch button an the EM Brake error disappears and reappears when released. Any assistance will be greatly appreciated.

[BobBoyce]

The purpose of unplugging is to get at the contacts for continuity testing of the wiring and checking proper operation of the brake switch.

Bob

[cgtech]

Hmm, what ohm readings are you getting from the temp sensor itself? (I think 400-1300 ohms is the range). The brake switch thing seems counterintuitive, I would think when the brake switch cut the park brake without a brake pedal range sensor reading to coincide with that brake pedal position, the error would show up, not disappear. Ahh the Ponderosa Ranch, I went there back in the day, before they bulldozed the place for another golf community.

[Tayed]

The ohm reading on the temp sensor shows open circuit, Must be a bad temp sensor. I was incorrect about the type of sensor. I guess this sensor is built into the motor.

Still lost on the Brake Coil. It dosent make sense to me that the Brake Switch Checks ok as a NC switch yet when the switch is open the EM Brake error disappears.

Another question I have is concerning the errors listed on the Curtis hand held. Is there any significance to the listing order of current errors under the diagnostic menu?

Thank you for your help

[BobBoyce]

The listing order depends upon the menu you are in. Log entries are alphabetized, while current and past errors are in the order they occured.

Ok, that test with the brake switch just identified your issue for you! If the error goes away with the brake switch unplugged, and comes back when reconnected, that means the problem is in the ground side of the brake circuit, between the motor brake connector and Curtis controller pin 5. Pin 5 is looking for +48V through the brake coil when the EM brake coil circuit is not energized. With +48V present coming through the brake switch to controller pin 12, and not present at controller pin 5, the controller detects a missing brake coil. You'll need to check all wiring harness and run plug connections between the motor brake connector ground side, all the way to the controller pin 5. There are a lot of wires involved. If you are persistent you can find and fix it.

If there is continuity from the brake ground side all the way to the controller pin 5, then your controller brake output is defective.

Bob

[Tayed]

Thank you Bob, it makes sense. I'll get on it tomorrow. If this doesn't work we will strip the body and accessories and it will become a parts car.

Ted Fischer

[cgtech]

Another thing you could try (not a factory approved test method, but not dangerous for testing), get any resistor near the middle of the range, then plug it into the harness where the temp sensor normally plugs in. This will allow you to test further without that "show stopper" code in your way. Resistor will simulate a working temp sensor.