This is mainly a professional tool but I highly enjoy it for testing window switches or any component I need to bypass to check for power or ground. http://www.devildogtools.com/popr3cokitwi.html You can use this too to "inject" power or ground to a component you are testing to bypass the load and diagnose exactly where the failure is at. It has saved me lots of time and headaches. Awhile back I used it to diagnose a failure of a secondary electric fan. The motor was bad but instead of using a jumble pile of fused jumper wire I used this tool. The circuit blew, indicating I had a short to ground at the fan motor. Simply just reset the fuse on the tool and you are good to go instead of replacing the fuse in the jumper wires you would have been using to bypass the circuit.

 

I own the Power Probe II, along with the ECT2000. Great set of tools. It saved me a bunch in trying to find my short. Turned out to be my alternator. Normally I take it with me off-roading but recently decided to stop using it because i the chances of needed it are next to none. Of course the next trip i went on i could have used it right there on the trail when Stephens truck kept blowing the EFI fuse.

It goes with me from now on

http://www.ntxtools.com/network-tool...I-ECT2000.html

with everything being electronic nowadays, its worth it