Another stereo yellow wire thread (1 Viewer)

[zakthor]

Truck came to me with busted head unit, replaced it with a kenwood excelon kdc x397. No issues or surprises on install except new speakers and speaker wire everywhere.

10 years of use the usb port is now broken. Wanted to upgrade to bluetooth and a stereo that supports that hands free fad... Bought a kdc x304.

Wife and son helped me match up the wire colors, big moment turn the key and unit wont turn on.

Im not going to believe its dead, check voltages and while red has volts when ignition is on, the yellow has no volts. Twisted the red and yellow together and unit powers.

Checked what i could and couldnt rationalize how i might have broken the constant 12v... Visit this excellent forum and read so many others that found the same thing.

Thanks!

I guess all my previous stereos didnt actually use the constant power?

I wanted to use an existing wire but couldnt find constant volts. Ran new wire from battery with 10amp fuse.

New stereo is pretty great. Is the 2020 model with Bluetooth 4.2. $118 and comes with a mic to talk on the phone.

Thanks for existing! Great forum.

 

[Cruzerman]

I think the constant voltage is used for the clock and maybe memory for stations and settings.

I like these units and have similar ones in my two FZJ80s. I like that a small USB drive gives me 32GB of music for $10. Plus, physical knobs and I tell myself that it isn't worth breaking in to steal.

 

[60 toy ota]

We've all had to get creative for the constant 12v. Since it's not drawing a lot of current, I just tapped into the inspection light circuit

 

[Freewheel]

If the yellow wire is fat, then it is actually drawing a lot of power. The little red wire is usually just a switching wire. Drives me crazy that stereos are wired like that... you should see the shenanigans that go on in the 24volt forum about this stuff...

 

[zakthor]

The old stereos' instructions said yellow was for constant 12v but both previous units worked fine without any v on yellow. This new unit won't even power up until I gave it volts on yellow.

I'm realizing now this new behavior is probably a good thing. Now that I've seen the tiny wires in that harness I'm certain they are too small to properly run the 88w rms stereo. Should be 14-16g wire if it was ever asked to draw that much. That is all I need is a burned wire in the harness...

I went and measured the amps on the new wire I hooked to yellow. I'm reading ~0.5 milliamps when car is off. And with music blasting louder than i can tolerate I'm seeing a peak of 1.7 amps == 20 watts. Reasonable for 4 little speakers playing real loud.

Conclusion is that this new stereo is in fact pulling it's juice from the yellow wire - and now that I've done the work I'm thankful to kenwood for denying me my old approach.

Tin foil hat time: Wondering... this new unit sounds so much better than the old one. YUGE difference. I don't believe it is actually much better sound-wise compared to the old one. Is it possible the old unit warn't getting the power from that little switched harness wire?