Throttle -- Safe Trial and Error

I'm installing a new three-wire throttle, having to change connectors and match up wires. I know which wires carry the 5 volts. If I connect the 5V wire from the controller to the 5V wire (red) on the throttle, will it be safe to guess at the ground and signal wires?

Thanks.

Generally the red wire is the 5v input to the thorttle. The dark wire (sometimes blue) is the ground. And the third wire (useally white) is the return voltage wire.

However I would not guess. Do you not have a volt meter? What are all the colors on your three wires?

You could possibly fry the throttle if you ground the signal and give full throttle.

With a voltmeter, you can figure out which wire is which on the controller side. Using battery negative as a reference, the 5v line will have 5v and using the meter in ohms mode, the resistance from the battery negative to the throttle ground will be near zero. The signal line will be something like 10k-20k ohms (do ohms readings with power off).

On the throttle, you could connect the 5v line and the ground like but keep the signal line open. Power on and check the voltage on the signal line. It should be around 1v and go to about 4v at full throttle. If you get the wrong wire, it will be OK with only two connected.

If you put a 1kohm resistor in each line from the controller, it should prevent sufficient current from flowing to destroy anything while you figure it out.

But it could interfere with the operation, so it might not work quite as expected until the resitors are removed once you figure out which is which wire.

All very helpful. Thank you.

I think I'll get some 1 kohm resistors. Would they be 1/4 watt?

The wire colours for the two three-pin connectors are:
red, green, black
& red, black, blue
I'm not sure which is the PAS (pedal assist) or which is the throttle.

The wires from the two throttles I have are:
red, black, white
& red, white, green

Tyro65 said:

I'm installing a new three-wire throttle, having to change connectors and match up wires. I know which wires carry the 5 volts. If I connect the 5V wire from the controller to the 5V wire (red) on the throttle, will it be safe to guess at the ground and signal wires?

Thanks.

Click to expand...

You don't have to guess. The negative side of the battery connection to the controller is at ground, on every controller I've seen. Unplug the battery. Turn on controller to discharge the capacitors. Put your meter in continuity mode or in lowest ohm mode if it doesn't have one. If you never done it, touch the probes together so you recognize how to check continuity, zero ohms if continuity.

Now check between the negative side of the controller's battery connector (your battery is not connected, right?) and whatever you think is the throttle ground. You will get continuity if correct, and then the other wire will not show continuity.

Hey, that's keeping it simple.

Thank you.