[roadster]

It may be different but on the latest Grom the TPS has three wires. Green is ground, yellow and orange provides power and yellow is the return signal wire. If you can just disconnect the yellow and orange, (or the wire that reads as having a 12 volt supply at the connector pin if its not yellow and orange) and it still blows the fuse its a fair bet that the short is NOT in the throttle position sensor itself but in the loom or the ECM. As the TPS is the most likely culprit you could try and find a second hand one to substitute.