This PCM Controlled, Fan Relay kit is inexpensive protection for an electric fan and a vehicle's wire harness. Relay activation by grounding the relay coil can be provided by most Powertrain Control Modules. Provides direct battery power, protects PCM from voltage spikes and prevents the fan from back feeding through the vehicle's wire harness. This kit includes: SPST 40-amp relay, 30-amp circuit breaker, relay base with 10' harness, crimp-on terminals and mounting hardware.