# No Throttle response also no error codes. Possible Pot?



## EE1010101 (Oct 27, 2014)

Hi Guys,

I am working on an EV gokart. It was working fine last week, but today I noticed at start up there is no response from pressing on the throttle. I'm using a sevcon gen4 motor controller and the motor is a motenergy1115ME. I checked the batteries and they are charged. I plugged in the USB-Can connector and loaded up the DVT software. No error code flashing light on the motor controller and there were no errors loading the dvt software. When I use the DVT software to monitor the throttle I can see a change in "Active/InActive" when the control is switched from Forward/Reverse, but when I press on the peddle there is no change in current/volts. 

Any ideas?


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## madderscience (Jun 28, 2008)

don't know anything about that controller but if it claims to be operating normally, check that the signal from the throttle pot is what you expect. The standard usually seen is a 0-5v analog signal with 5v being full throttle, so it should be easy enough to test. Verify this is the case with your controller documentation, then you can check the signal at the controller end, then work backwards to the pot, then back to its source of 5v until you find where it isn't working.

Some controllers have a "hi pot lockout" feature meaning if the controller is turned on or enabled and the throttle signal does not read zero, it ignores the singal until the throttle signal returns to zero. So you can check if the pot isn't zeroing out. This is to prevent sudden unexpected movement when the controller is turned on.

Just make sure to ensure the kart won't suddenly move if you bump a loose wire and restore throttle contact.


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## EE1010101 (Oct 27, 2014)

madderscience said:


> don't know anything about that controller but if it claims to be operating normally, check that the signal from the throttle pot is what you expect. The standard usually seen is a 0-5v analog signal with 5v being full throttle, so it should be easy enough to test. Verify this is the case with your controller documentation, then you can check the signal at the controller end, then work backwards to the pot, then back to its source of 5v until you find where it isn't working.
> 
> Some controllers have a "hi pot lockout" feature meaning if the controller is turned on or enabled and the throttle signal does not read zero, it ignores the singal until the throttle signal returns to zero. So you can check if the pot isn't zeroing out. This is to prevent sudden unexpected movement when the controller is turned on.
> 
> Just make sure to ensure the kart won't suddenly move if you bump a loose wire and restore throttle contact.


Thanks for the help, When I have the kart hooked up using the USB-CAN connector the throttle voltage is around .2-.3v. When I press on the throttle it does not go any higher. It literally seems like the kart is fully functional and the only issue is that the throttle does nothing. The kart switches on like normal and I can hear the controller "click". It makes noises when I switch on the forward switch. I can also see the forward setting on the dvt software go to :Active yet when I press on the throttle...nothing.

I reloaded the .dcf file to a working backup and nothing worked


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## madderscience (Jun 28, 2008)

sounds like that is where the problem is. If you are looking at the voltage via USB CAN data, you would then confirm it directly with a voltmeter on the throttle input wire. If you get the same answer, then diagnose why the voltage doesn't change when you move the throttle pedal. Maybe its 5V supply is no good, maybe the mechanical linkage isn't working right and the throttle pot isn't turning when the pedal moves; maybe the throttle pot is no good, for example if it was supplied too much voltage and was burned out, maybe something is shorting the output of the throttle pot and keeping it from moving across its whole voltage range.


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## piotrsko (Dec 9, 2007)

You are also looking at the software (which likes to misrepresent) you need to look at the mechanical, like fusing and whether or not there are actual voltages applied to all the components. Throw the cart up on stands to let the drive wheels spin, and dvm everything.


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## EE1010101 (Oct 27, 2014)

I check the throttle voltage on the 35 pin connector going into the motor controller and it was the same .3 v 
I took the 35 pin connector apart and noticed the wires are not soldered in and one of the wires needed to be pushed occasionally or it was causing a 4 light contractor error on the motor controller, but otherwise everything looked exactly the way it did when the kart was running.
I was able see a change in voltage when I press the acceleration pedal. It goes from .2-.3 (constantly changing when the acceleration is not pressed) to 9.3v when the acceleration is held down. This is from the monitor section in the DVT software. I noticed the throttle on the power maps section of the DVT software was changed to a much higher value. I have the original settings in my notes and noticed the change. I changed it back, but still no success. I e-mailed thunderstruck to get the orignal .dcf for the ME1115 motor. There are no errors coming from the motor controller, but there is a definite noise change when the kart toggle switch is moved to the forward position. Its like a repetitive whine that used to only happen the acceleration pedal was pressed, now it seems to happen as soon as the toggle switch is moved to the forward position.

If it was the throttle pot would the throttle voltage be changing?
Could something like a short in the wiring cause a problem like this?


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## EE1010101 (Oct 27, 2014)

madderscience said:


> sounds like that is where the problem is. If you are looking at the voltage via USB CAN data, you would then confirm it directly with a voltmeter on the throttle input wire. If you get the same answer, then diagnose why the voltage doesn't change when you move the throttle pedal. Maybe its 5V supply is no good, maybe the mechanical linkage isn't working right and the throttle pot isn't turning when the pedal moves; maybe the throttle pot is no good, for example if it was supplied too much voltage and was burned out, maybe something is shorting the output of the throttle pot and keeping it from moving across its whole voltage range.


I checked the connection and I'm not sure what happened, but now the throttle voltage showing on the DVT software does increase when the acceleration pedal is pressed. Even when it is not pressed I can see .2-.3 volts which seems wrong. I don't get why it is not 0, I measured the voltage at the pot pin on the 35 pin connector and it was showing .3 volts. Mechanically I can see the pot move as the throttle pedal is pressed. I didn't install it, but the pot looks pretty new.



piotrsko said:


> You are also looking at the software (which likes to misrepresent) you need to look at the mechanical, like fusing and whether or not there are actual voltages applied to all the components. Throw the cart up on stands to let the drive wheels spin, and dvm everything.


The throttle voltage on the dvt software matched what I got using a voltmeter and measuring the wires coming from the throttle pot going into the motor controller. I didn't take apart the pot to check the connections inside. is that something I should try?


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## EE1010101 (Oct 27, 2014)

Problem solved. I loaded a backup .dcf file I had before the motor controller settings were ever changed and it worked.


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