The amp is grounded, which is connected to the harness

 

Yes. But there is a different ground wire for your steering controls. Can you cycle through the trip button? Mpg, temp, dte, etc

 

What do you mean cycle through the trip button?

 

https://maxima.org/forums/5th-generation-maxima-2000-2003/339182-trip-button-steering-wheel-not-working-after-installing-stereo.html

 

I still don't know what trip button, I have a 2001, do I even have a trip button?

 

It's possible you don't have one. It would be next to the MODE button on the left-hand side of the steering wheel...



Here is an '01 steering wheel w/o the TRIP button. Note the absence of the button and the second LCD on the tachometer...

 

Yeah, I don't have one, what else can I check?

 

this is dope.

 

i would check the wiring diagram for your 5th gen or search for a write up for making the steering controls work with your year maxima. i suspect that you need to ground the steering buttons (in an 02 it's the brown wire). the "trip" button was just a simple test.

 

Which wire should I ground from?

 

Take a look at the steering wheel portion of this write up...

https://maxima.org/forums/audio-elec...ng-colors.html

 

No sort of grounding will work.. maybe I need to go to school to be an electrician

 

So you have grounded the brown and white wire to the chassis?

 

Yes, if this helps. I can activate the button function with a grounded wire (if one end is connected to the chassis and I touch the open end to the programmed button, it will activate. However it still will not work with the physical steering wheel buttons

 

Dear friends I hope that you can help me out, I'm making basically the exact same setup but I have a few doubts.
The first being, the Alpine amp must receive a 12V power, but from my car cable harness I only have one 12V cable that is supposed to be soldered to the pin of the USB car charger, so how do I provide the current to the amp?
Thank you so much,
Roberto