I have a Pressure Pro TPMS installed in a 08 Silverado & I wanted to hard wire the power instead of using the lighter socket. The head unit end I secured this way:
A little internet searching & I found there is a key switched hot lead (300 milliamps - enough for the Pressure Pro TPMS)& ground just waiting to be used for something under the dash on the drivers side. It's called the "mid buss electrical conector", mounted on the firewall on the left above the e-brake.
Cover looks like this:
Find Connector X-14;
You want to use pin 1 for ground & pin 8 for power.
(Pin 2 is 15 amp, pin 5 is 30 amp, pin 7 is 10 amp, & if present, these are hot all the time, so be careful!)
Run the cable from the TPMS over the console to the connector and terminate the ends of the power leads with insulated narrow style female spade terminals.
-Steve
edit for minor typo Oct 13