Device for finding “short circuit” in the car

Hello Samodelkin friends and site guests! Many of you have cars that sometimes need to be repaired by hand. Often a “short circuit” occurs in the wiring of the car due to the chafing of the wires when they touch the car body. To find this malfunction, I bring to your attention another homemade product. This is a device for finding a “short circuit” in a car. Here is a diagram of the device.
For this device we need the following materials and tools.
Materials: power supply unit for 12V, any relay for 12V, with one pair of open contacts, 8-10 meters of two-core wire with a cross section of 0.5- 0.75 mm
Crocodile clips – 3 pcs, car bulb 5 – 21W – 1 pc.
Momentary button – 1 piece, car connectors “male” – 2 pieces, toggle switch – 1 piece
Two small plastic boxes
mounting wire for soldering, a small piece of 5 mm plywood, bulb holder.
Tools: electric drill, drills, screwdriver, hacksaw for wood, screws and nuts M3, soldering iron, tweezers, wire cutters, pliers.
Let's start making.
Step -1 . We drill the necessary holes for the toggle switch, button, cartridge and relay in our boxes.

Fixing it all in its place.
Step -2 . I cut out the bottom covers of the boxes from plywood and screw them to the boxes.
The scheme works as follows. One box contains a toggle switch, a button and a light bulb. The two wires from the light bulb are plugged into the blown fuse connectors instead. Before searching for “short circuit” from the car battery, it is necessary to disconnect the plus of the ECU power supply, and after eliminating the malfunction, reconnect it to its place. We disconnect the negative terminal from the battery, connect the wire to it from the open contacts of the relay, and the second wire from these contacts to the negative terminal of the battery. When the button or toggle switch is turned on, the relay is triggered and with its contacts connects the vehicle mass to the battery. Before searching for “short circuit”, we find a blowing fuse, remove it from the socket, and insert the connectors from the light bulb instead. It should burn at full heat. According to the automotive scheme, we find the power circuits for which our fuse is responsible, and in turn we check all the fuse power circuits, not forgetting to periodically turn on the relay with a button or a toggle switch. As soon as the light goes out, in this part of the tested wiring harness and look for the place of their closure. Then we isolate the closing wires from each other, if necessary, replace them with new ones.
This is how this device can be used to find and eliminate the “short circuit” in the car. Do you need such a device, decide for yourself. For example, it was very useful for me to search for “KZ”.
I wish you all health, success in your work, and see you soon.