# Curtis 1231 trouble.



## EVfun (Mar 14, 2010)

gojo said:


> My motor either runs with out the accelerator being used, or doesn’t run at all.
> 
> When I first went to start the car today, the motor started running without stepping on the accelerator. It didn’t run very fast, but it ran until I shut off the controller. Then when I turned on the controller, the motor wouldn’t run at all even when I stepped on the accelerator.




First, try shorting out the 2 pot box terminals at the controller with a jumper wire. Be careful to never allow the power on the ksi terminal touch either of the pot box terminals. Tape that terminal off while messing around, pack voltage on the pot box terminals will kill the controller. With the terminals shorter out the controller should NOT run the motor at all when turned on. If it does you have a controller problem and shouldn't operate the vehicle until it is fixed. If that does keep the motor off then I would investigate the throttle linkage and pot box.

Next, check the pot box and linkage for problems, like binding or not returning to the stop on the pot box. The pot resistance needs to be under 200 ohms with your foot off the throttle, reliably. You will have to disconnect the pot box terminals from the controller to test this. If the numbers bounce around each time you release the throttle, either because the pot inside the box is worn out or because of issues with the throttle linkage, there is going to be problems.

If you can't find it in either place please post what you have found. There are plenty here who have used Curtis controllers so someone will have more ideas.


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## gojo (Feb 1, 2011)

EVfun said:


> First, try shorting out the 2 pot box terminals at the controller with a jumper wire. Be careful to never allow the power on the ksi terminal touch either of the pot box terminals. Tape that terminal off while messing around, pack voltage on the pot box terminals will kill the controller. With the terminals shorter out the controller should NOT run the motor at all when turned on. If it does you have a controller problem and shouldn't operate the vehicle until it is fixed. If that does keep the motor off then I would investigate the throttle linkage and pot box.
> 
> Next, check the pot box and linkage for problems, like binding or not returning to the stop on the pot box. The pot resistance needs to be under 200 ohms with your foot off the throttle, reliably. You will have to disconnect the pot box terminals from the controller to test this. If the numbers bounce around each time you release the throttle, either because the pot inside the box is worn out or because of issues with the throttle linkage, there is going to be problems.
> 
> If you can't find it in either place please post what you have found. There are plenty here who have used Curtis controllers so someone will have more ideas.


Both times this happened, I left the power on to the Controller without using it for several hours. Could that have damaged the controller?


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## gojo (Feb 1, 2011)

EVfun said:


> First, try shorting out the 2 pot box terminals at the controller with a jumper wire. Be careful to never allow the power on the ksi terminal touch either of the pot box terminals. Tape that terminal off while messing around, pack voltage on the pot box terminals will kill the controller. With the terminals shorter out the controller should NOT run the motor at all when turned on. If it does you have a controller problem and shouldn't operate the vehicle until it is fixed. If that does keep the motor off then I would investigate the throttle linkage and pot box.
> 
> Next, check the pot box and linkage for problems, like binding or not returning to the stop on the pot box. The pot resistance needs to be under 200 ohms with your foot off the throttle, reliably. You will have to disconnect the pot box terminals from the controller to test this. If the numbers bounce around each time you release the throttle, either because the pot inside the box is worn out or because of issues with the throttle linkage, there is going to be problems.
> 
> If you can't find it in either place please post what you have found. There are plenty here who have used Curtis controllers so someone will have more ideas.


I followed your instructions and something interesting happened. When the pot was connected to my ohm meter, it showed about 5k ohms. When I pressed down slightly, the needle moved to infinity, and when I pressed a little more, it went down to zero.

Am I correct in thinking the pot needs replacing? It is a cheap Chinese pedal type.

Thanks for the reply, I think you nailed it.


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## EVfun (Mar 14, 2010)

You might be able to adjust the throttle pot so it starts at the zero ohm position, if this reliably repeats at that spot. That kind of pot response will cause all sorts of problems. 5000 ohms is the full throttle command (between 4500 and 5500 ohms.) Over 5500 ohms is and error that should stop the controller from operating until it sees a pot resistance under 200 (or is it 500?) ohms -- until it sees zero throttle again. Roughness in the resistance change when it's moved causes jerky throttle action. This pot is most likely going to have to be replaced sooner rather than later.


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