radio wiring 2006 jetta mk5

Hi. I’m trying to complete a DIY install of an aftermarket head unit stereo (Pioneer DEH-P5100UB) in place of the stock unit in my 2006 Jetta 2.0t. I pretty much figured out what wires go with what wires, but after cutting/splicing them all together, the Pioneer is not powering up.

On the Jetta wiring side, I did not connect the “CAN +” and “CAN -“ wires. I know they have something to do with ignition and/or anti-theft. But I’m not sure if they need to be connected and if they would prevent the radio from turning on if not connected. It’s entirely possible that I wired the 12v constant wire to the 12v switched, and vice versa (both were the same colours of RED / yellow on the Jetta side!). Perhaps that’s it? I also did not connect the separate black cable with the metal connector at the end, since it won’t plug into the Pioneer (I used to think this was a power cable, but now I’m pretty sure its just the antenna — which should not prevent power).

p.s. My Jetta is a Canadian model, where the stock radio did not turn off once you removed the key. It seems you had to manually turn it off, whether you open the doors or not.

Do not connect either CAN wire to anything on the aftermarket radio. Obviously there is not a switched power source in the radio harness. you will have to find a source that goes on and off with the key, or connect the radio's red wire with the radio's yellow wire. If you do the latter, you will have to turn the aftermarket radio off manually just as you did the OEM unit.

Metra makes a harness for that car that utilizes the can signal to produce a switched output, but you already cut the plug off of the vehicle, so that is out.

Thanks bunches for the quick reply. I can rewire the stock harness to the car wiring if necessary, in order to install the Metra harness you recommend. But if I've understood correctly, the CAN-Bus wires and their function simply allows you to switch the radio off automaticaly, when you remove the ignition key. IOW, it's not what is currently preventing the radio from powering up?

Do you have 12 volts on the Yellow wire and the Red wire of the aftermarket radio?

Yes, the Pioneer harness has 12v wires (constant and switched). But I checked the voltage of the wires coming directly from the Jetta, and I could not get ANY to register any voltage! I touched one probe to the ground wire (which should be the TAN wire on the Jetta), and the other probe to the two wires that I identified as 12v constant and switched (both are RED / yellow). Nothing. I then tried touching the second probe to every single other wire.... I got zero volts, even when the ignition key was turned until the dashboard panel was lit up.

Shouldn't something register?? Any clues as to how to proceed?

Put the black meter lead on the chassis of the car. If there is no voltage on the RED / Yellow wire, you have a blown fuse somewhere.