Carpokes

I'm finally getting my blaupunkt Bremen sqr 46 dab radio head unit installed. Coming from a Kenwood kdc-3057u. When I bought the car years ago the kenwood worked, but it died some time later.

So now years later, I've pulled the kenwood out. The harness is a bit of a hack job. PO seemed to have pulled constant 12v from the EQ AMP PWR harness and not from the radio power harness. He pulled switched power from the radio power harness.

I checked all fuses in the fuse box, all were fine. I dont have a sunroof relay in spot g18 (internet told me it powers radio stuff too, I dont have a sunroof on my car)

So far I have deduced (please correct me if I am wrong):

- I should not connect any wires from my Bremen to the 3 wire loom of the EQ AMP POWER harness
- I should find constant 12v, switched 12v, ground in the radio power harness
- constant 12v in this radio power harness should be a red white cable, switched 12v should be a double green cable, and ground should be a double brown cable
- the speaker harness has 8 wires, 2 for each speaker
- there is a big antenna wire paired with a tiny black antenna wire. This tiny wire should be hooked up to my Bremen auto antenna wire (blue)

Issues
- for the life of me, I cannot find constant 12v with my multimeter, not even on the EQ AMP PWR harness that the PO used (remember i once saw the radio work, but since I took possession, it didn't work iirc)
- the what i believe should be the constant 12v cable which is red and white on the radio power harness is small and less thick than the constant 12v on the EQ AMP power harness. I doubt this tiny cable is safe.
- switched 12v is also unfindable. My clock works, my car starts, the dash lights turn on when I switch the ignition on. I use a fluke multimeter set to V with the straight dashed line symbol. I ground the black side on the old radio that's on my floor
- I swapped out the g12 relay for the horn relay, horn keeps working with both relays. Still couldn't find switched power.
- there's an unknown two wire bundle in the car. One wire is green, the other brown green. They are not connected but seem to have a factory harness and sit on the passenger side of the radio space
- I read somewhere there is a sort of hidden relay that powers the radio and sits near one of the relays of the sunroof. It's in a panel box under the dash, drivers side but supposedly at the console side. I cannot find it.


Hope someone can help me clarify these issues. I will attach some photos here:

EQ AMP PWR harness. Note how the PO connected yellow (constant 12v) to the big red white cable. This cable doesn't seem to give any power at all when measured at the old connection. Speaker harness. I have a diagram shown below that I use and confirms these are the correct speaker wires. Radio power harness. PO attached the small red cable to the two big greens for switched 12v. Cannot find 12v when ignition is turned on. Close up of what should be the constant 12v wire from this radio power harness. It seems way too small to safely deliver 12v constantly.
Mystery green and green brown wires. Not connected. Big antenna and tiny power booster antenna. I connected the tiny black to the auto antenna wire (blue) from the Bremen. My multimeter settings are they correct? My multimeter test to find switched 12v The picture I found on internet that identifies the wiring Bremen manual pinout info Old radio pinout info in Dutch

Update

I'm afraid I am incompetent. But I'll post here for future people that know nothing about electricity but want to work on their car.

I switched the multimeter probes around and am now using red to touch the car chassis with battery connected. I touch the black probe to the wire I want to check. Settings of my multimeter above were fine.

This gave me a permanent 12 volt reading at the EQ AMP PWR harness (big red white wire). Also gave me permanent 12v at the tiny red white wire on the radio power harness. Gave me good switched 12v at the double green wire in the Radio power harness.

Then I removed black terminal connection at car battery. Took multimeter m, set it to ohms with audio beep. OL reading means bad. Any reading other than OL or infinite (same thing) is good. Touch red probe to chassis and black to the big brown wires in both EQ AMP PWR and radio power looms, both gave good readings.

I think this means I can actually go ahead and fix this...

The only question I still have is whether it is safe to use the tiny red white always on 12v cable to attach to the stereo.

I'm also unsure which is the lighting cable at the radio power harness (one of the three red black ones?) And what use they have in my new radio.

Not incompetent, just learning new skills! Outside the Matrix, everyone has to learn.

On most multimeters, you want to put the black probe on the ground side, and the red probe on the positive (12 volt) side. If you reverse the probes, most multimeters will show negative voltage -- e.g., -12v. However, to really keep you guessing, a lot of multimeters will let you plug either probe into either port on the multimeter -- so if you are seeing positive 12 volts when putting the red probe to ground and black probe on the power wires, you might check to make sure the red probe is plugged into the positive port and the black is in the negative port.

Re chassis ground, it's important to understand that disconnecting the negative battery terminal will eliminate the ground path back to the battery, but all of the chassis ground points are still connected together via the chassis, so grounded wires/components will still appear grounded when you check for continuity to the chassis. (You just won't have continuity between ground wires and the actual negative battery post.) Think of the chassis as a big steel beam with all the ground wires bolted to it. As such, you will have continuity between all of the ground wires, and between ground wires and the steel beam (chassis), whether or not that steel beam is also connected to the negative battery post.

Thanks for the explanation! Really helps to understand what I'm doing better.

As for the radio, I've made good progress. Now that I know the ground, switched 12v and constant 12v are available, I connected everything but the constant 12v.

Can a Carpokian confirm that I should use the red white small cable (see my close up in OP) of the radio power harness to provide constant 12v?

Additionally, can someone explain how to find out which of the three tiny red black wires on the radio power harness must be connected to the illumination pin on the new radio? I tested them all and they show no voltage at no key, with key, key turnt 1 step and key turnt 2 steps.

I'm excited to test this thing after all these years!

Update: after researching some more I attached the red white wire to constant 12v on the radio. I left the 3 red black wires alone.

The radio works but doesn't turn on automatically when I turn the ignition key. It actually doesn't react at all to the key. If I press the radio's on button, it turns on even without a key present. I think I probably messed something up. Any ideas?