Old Pioneer head unit pinout

Hello everyone, does anybody have a clue what is the pinout of this old head unit? There are only 5 pins, so I suppose there is an output only for two speakers with a common ground. Figuring out the ground will be easy but what about the rest? Any ideas? thanks

Do you have the old harness or wiring? if not its not hard to get connectors in there, in those old radios if I remember correctly (its been awhile) then they have power, ground, illumination and or speaker connections the best way to do this is to find your power and ground and play around with the connections that are left to see if they push speakers. if I remember correctly than it should be like this (not in actual order or pin position) 1.power 2.ground 3.illumination 4. speaker + 5. Speaker - that's not in say the actual order but that's how it should be, and it ran all the speakers off one set of leads in series instead of having multiple speaker outputs like todays radios

There will not be an illumination wire. There is a switched 12 volt, a ground which is chassis ground plus the negative speaker wires. A left speaker wire, a right speaker wire and a power antenna output. Do you have an ohm meter? It will be very easy to figure out which wire is which if you do have a meter.

If you do have a meter, this is what I need you to do. Power switchof radio in the off position. Meter set to Diode test (this will have a symbol of a diode) Look to the left of here and see the section about Diodes to see that symbol. Press and hold the black meter lead to the chassis of the radio. Touch the red lead to the first pin on the plug and write down the reading on the meter. Do this for the remaining 4 pins and post what you find here. Then place the red lead to the chassis and touch the black lead to the pins. Post that info as well.

I 'm quite familiar with electronics (studied electrical engineering but I work on IT) and i do have a meter, so I will post the measurings as soon as possible. I do not have the harness by the way.

Ground pin will be directly connected to the chassis of the radio. As stated earlier this pin will also double as both negative speaker wires. The power wire will read between .400 and .600 with the meter leads in one configuration, and a much higher number with the leads in the other configuration. It is reading across the reverse polarity protection diode. Make sure the balance is in the center position. The 2 speaker wires will give very near the same readings. This number may or may not be the same with both lead configurations. But they will read very similar readings in the 2 different configurations. The remaining pin will be the power antenna wire. TO verify this, turn the power on and check for continuity between the switched wire to that pin.

this is really close. http://retro-caraudio.servehttp.com/guide2/images/Brukermanualer/Bilstereo/Pioneer/CassetteReceivers/KP2020%20USER%20MANUAL.PDFyuk

quiet rural missouri, near KC.

If your system moves you physically and not emotionally, you have wasted your money.