Seat Leon Radio Connection Issue: New Radio Install, Ignition Switch, Voltage Drop & Wiring

Hello, I have a problem with connecting the radio to a friend. Colleagues broke into the leon and mowed the radio, bought a new one but there is a problem with the connection. It's about turning on the radio after turning the ignition switch does not want to work. What is going on measuring the pins coming out of the leon is so red solid plus lower black mass and I found gray from which the voltage goes out 12v after turning the ignition switch now so the radio comes out yellow battery + that is constantly 12 lower black mass and red which should go under the ignition but connecting it to the gray with the ignition voltage drops to 2.6 V and does not turn on. The radio only turns on like the red one under the 12 V steels. Then I did so with the red radio I took out the pin and connected to the 12 to the ignition, the voltage was measured and it is 12.5 but when connecting for a short time, the mass is lost back to the 2 V. I thought that something with mass and filling directly under the mass of the battery and the same. I have no idea anymore. I checked his radio at home and it works ok, then I took mine and the same does not work ... And we want it to work with the ignition switch because it is a failure to turn off the radio manually ... Maybe someone has an idea ... ?? Radio is a pioneer. And mine and his.

Have you checked the fuses? If someone pulled the radio out of the chama, it could have a short circuit and the fuse may have blown Knowing the vaga, it will be red 10A

Fuses checked. Anyway, it would probably not even play a permanent one but maybe I am wrong. But they were checked ... Why is there such a drop in voltage ... I also tried the reverse with the cables on the radio, i.e. the ignition switch for permanent and permanent ignition switch but the same. The radio only turns on after bringing the red from the radio to steady 12

Added after 2 [minutes]:

Hmm, red, we checked blue 15 from leon's diagram. Anyway, at the end I figured so much that I managed to connect it so that after turning off it played but after switching off the ignition he shot just blue 15 and we gave up for today because it's the second day after work and I can not get over it: /

What radio model? In most radios, only 2 (say 3 if you count the mass, but usually we can let the mass go away because it will go quietly through the antenna and this should not cause any interference) wires. One is, of course, a constant 12V, the other is a pulse from the ignition switch. If you have the original ISO cubes (black power supply and control, brown outputs for speakers) then here you have the diagram.

Black and brazawe or AiB and I get out to 8 mass and 7 solid 12 and 3 after the ignition ...

Cable for impulse from the ignition switch on the radio are you sure? Because someone could have already chilled something in the ankle if the radio was used.

Rather so because I play golf with the ignition: / from the lighter 12 goes from the ignition or permanent or from what the fastest to pull a new from the ignition to be 100% sure if it is not leona fault because I only see a problem there.

Added after 6 [minutes]:

Radio colleague pioneer deh-p3100ub and my mv-180 or something bought two years ago

Dammit, it looks poor. The problem would typically indicate a blown fuse or a damaged pin because I've had this situation several times in both A4 and A3 as well as in Octavia mk1 and probably even once in Golfik mk4. If I come up with something, I'll talk to you.

And tell me because on Saturday we will review carefully calmly and not after work, if this switch fails, if it connects permanently, it will be unloaded or not, and just remember to turn it off manually?