Circuit Protector

Winch will pull for only 15 seconds, will stop for 30 seconds before pulling again

This sounds like the Circuit Protector is getting hot and opening, then it must cool down to be used again.  This can be verified by taking the circuit protector off the main line and hooking the Main Red 2 gauge cable to the battery direct and see if the winch will stop working after 15 seconds.  This is ONLY to verify the circuit protector is getting hot and opening the circuit to protect the winch motor from damage.  A NEW circuit protector should then be installed, never use the winch without a circuit protector because the circuit protector is design to protect the winch motor from damage