Motors Don't Run

Our small (2 1/2 inch) CIM motors do not work when in our circuit. When plugged into the speed controllers, no matter how we program or set the pwm cables the motor will not run in any direction. The speed controller is getting +12.56 volts but the output is negligible, something like .24 volts. We cannot seem to find out what the problem is. We know the motor works since if we directly connect the motor to the battery for very short periods of time, it spins.

Any suggestions?

Would you please go more into detail on how you are you wiring your bot? (starting from where it’s getting power from and where it’s all going). Load the default into the Robot controller and use PWM 1 and 2 (for the two drive motors), it should work if everything is wired correctly. We did have a problem where our radio wouldn’t work, but after tethering and testing with it, everything seems to be fine.

While you are answering Arefin’s question, Have you tried another Victor. Just as a quick test to rule that out.

Last year we had a problem were the PWM cables took alot of force to seat all the way in to the victors. Look closely at the cables.

The LEDs on the Victors will flash orange on and off if there is no PWM connection…

We were able to get the motors running by setting up a really simple second circuit, used to power one motor individually. It worked.

I don’t see how we could get four defective Victor 884 Speed Controllers from first.

However, the circuit it wired pretty much like this:
Battery -> Switch -> 40 Amp Fuse -> Speed Controller -> Motor.

It really sounds like your victor’s aren’t getting a signal from your pwms. It has already been said but to re-emphasize: If your pwms are connected correctly to the victors and to the rc, they victor indicator lights will be SOLID orange, red, or green, and in some cases not lit at all. In years past, the hole the the pwm plugs into (on the victor) had a shoulder in it that kept the pwm from plugging in properly. Removing it helped the pwms mate much better. You can get rid of it by CAREFULLY using a small drill bit or similar attachment on a dremel tool. Then vacuum out (or blow) the plastic bits.

Because of the shoulder on the Victor its very hard to tell if all the pins from the PWM Cable seat all the way in and the only way to find that out is to turn on the robot and see if anything moves. Like many said you could remove the shoulder or enough of it so that you can see what your doing and just clean up any plastics bits. Everyone makes mistakes so double check the wiring you may have attached everything on the Victor backwards. The wiring should look like the attached image. If anything try using one of last years Victors and see if you get the same problem to rule out a defective Victor.



The probability that you have received 4 bad Victors is simply astronomical.

If you have good PWM cable connections (see previous posts by Dan and I) and power to your Victor, then the problem is almost certainly in your software.

Let us assume that you have CIM/Victor #1 plugged into pwm01 and, in the software, you are controlling it by p1_y: You can try to (1) plug a servo into pwm01 and see if you are controlling it or (2) put a printf statement next to your code statement to indicate to you that you are actually getting to that statement.

Your Victors are not bad. I guarantee it…

Best of luck.


Check if the PWM cables are hooked in to the RC the right way. I know, I know, it’s kinda basic, but if your working inside the robot, it can be hard to see which way the wires go. So, double check if the cables are reversed or not.

As others have pointed out, the Victor talks to you. Download the manual from the IFI website and use it to determine if the Victor is getting the correct commands. As to the PWM cable, a correctly inserted cable will have about 1/8 inch of the connector body showing when it is inserted fully. If the LED is showing correct operation (i.e. full on Red or Green at joystick maximum) then the Victor is happy and operating. That only leaves defects between the motor and the Victor. Look for bad crimps or an open circuit. With the power off a VOM should show a short across the Victor output terminals with a motor connected.
If the LED is not changing or showing no PWM then check you are connected to the RC correct PWM ports and have the PWM inserted correctly at both ends. After that it becomes software.

For a quick check of the software, plug a servo into the PWM you programmed for the drive motor. It should move when you move the joystick.