Question about the Low Side Switch

This circuit is Mikes that he worked up for me earlier.

In this circuit if my PIC processor failed would my Load have the full 12v applied to it all the time?

My load would be brake lights and they draw about 6.7 amps@ 12Vdc. Is R4 required and if so what is a reasonable value and size for the resistor? Surely I can't get an 80 watt one!!

Thanks

The circuit has R1 (the load) and R2. There is no R4. If the 4 ohm load has 12V across it then its current is 12V/4 ohms= 3A and it dissipates 3A squared x 4 ohms= 36W.

Yes ... got it. Thanks