A power probe is made to help you test something without the headache of guesswork, and it has multiple attachments for piercing different sizes of wire there for making it simpler. And the actual Power Probe is quite a unique & expensive tool. But I made up some testing leads on a budget with primary wire and alligator clips. Each lead pictured below was made for different applications.
Alligator clips come in various sizes depending on the applications needed. I’ve had to make several types of testing leads for various areas of cars from heater blower motors to headlights, taillights, backup lights, switches, and voltage regulators. (This can work for any area of the vehicle that may need testing) The testing possibilities are endless. I’ve even found some test probes from old multimeters and solder primary wire for the extra tight places inside connector plugs. It even works great in fuse boxes to test various items when transferring from the load side of the fuse box to the accessory side of the object it’s powering. (It’s a lot easier than replacing fuses)

This particular wire I used on my old truck to install the turn signal switch. ( the steering shaft needs to be grounded to the body of the truck or frame.)

testing a power window regulator

My battery is used here as my power source and the ground or negative cable is connected to it which will reverse the power to my window regulator making go down while checking its status.

Notice the larger alligator clips. For bigger jobs

testing a power window regulator. The ground wire is in the picture.