Replaced JBL head unit, wanted CarPlay

I replaced my HU with a Pioneer AppRadio4 leaving stock JBL amp in place. Prior to ordering I warmed up to the idea after seeing how easy it was on this thread: New install: JVC GPS replaced JBL HU | PriusChat

The dash removal really is easy - I just used my fingertips. 10mm socket to undo the 4 bolts securing the HU and a flathead screwdriver to depress the release catch on each of the HU wiring harnesses. Used PAC's products to allow me to keep the JBL amp and speakers, along with the steering wheel controls. You only end up needing to wire together 4 wires and I just used wire nuts I had leftover from previous electrical work on my house.

The hardest part was probably programming the steering wheel controller (PAC SWI RC). It's sort of like programming the old universal remotes. You press a button on the PAC unit, hold it, press it again, press the steering wheel controls in a specific order, etc.... It wasn't too complicated but you had to do it all in order and in a certain timeframe. I had someone help by reading off the order for me so I could focus on the button mashing. Looking back I might redo it and make the "Mode" button on the steering wheel act as a mute button instead. Who changes the source/mode using that button anyway? Plus now everything you'll want to do will be on one source - the USB connection/CarPlay.

I ran the mic wire behind the HU, left along the underside of the steering wheel, then up the rubber moulding on the driver side door opening. Popped out at the top left corner of the windshield and then ran it across to just above the rear view mirror. It was really easy to work the mic wire into the moulding and between the ceiling material and the rooftop - almost didn't need any tools, just a screwdriver to gently push the wire into a few tighter spots. Popped out the plastic moulding just behind the sunglasses holder and put the mic there. With the moulding back in place the mic just pops out of the rear left corner, facing the driver.

Ran the USB and AUX connectors down from the HU, popped them out through the stub just to the left of the cigarette lighter (cubby below the HU/shifter). I put the AUX here because I was sure how to wire up the AUX in the bottom of the center console where the other cigarette light is.

Here are a few pics of the install and of the firmware update I did later:



You can see in the pics that I initially installed using the stock mounting brackets but I later reinstalled using the brackets that came with the Scosche faceplate. The Scosche brackets provide better support for the faceplate to keep it stationary whereas the stock brackets allowed the faceplate to move around a bit, which was annoying when you rested your hand on the faceplate while using the HU touchscreen.

I also have been having some trouble with fader controls. I noticed if I tried to fade to the rear to even out power between front and rear speakers, the power/volume would fluctuate randomly between front and rear speakers. This was really annoying/distracting.

Not sure why, but there might be a problem with the PAC interface. I've been removing the HU repeatedly, trying to troubleshoot. My most recent attempt has been to bend the contacts of the black 8 pin connector (connects the HU RCA's to the PAC interface). I slightly bent them outward thinking they would make better contact with the internals of the PAC interface. I've also been adjusting output power levels via the HU controls (onscreen) by upping power to the rear speakers (I think this is called Speaker Levels), in combination with fading to the rear (the more standard/familiar fader & balance controls).

Previously I tried increasing and decreasing the power boost outside the HU controls, as well, using the PAC interface's dip switches. The switches provide 0-7dB boost depending on dip switch setting. I found a 7dB boost seemed most similar to the power level of the stock HU, which means setting the 1, 2, and 3 dip switches to On.

I had some trouble with the PAC-SWI (remote interface for steering wheel controls) after initial install, too. During one of my reinstalls of the HU while troubleshooting the fader/power fluctuations, I reprogrammed the remote to configure the Mode button on the steering wheel to act as a Mute button instead of a source changer, as mentioned previously/above. Reprogramming the remote was easy, but I noticed the Siri button (which you have to hold down for about 1-2 seconds to activate, btw), and the answer & end call buttons on the steering wheel had stopped working properly. I tried reprogramming the controls 3-4 times with the same results. Ultimately I unplugged the remote from the back of the HU and plugged it back in, and this seems to have fixed it. Must've gotten loose during one of the reinstalls.

 

Added some pics and some more info

 

I didn't have a backup camera and didn't add one. The post I linked at the beginning has a walk-through of how to do it, though. He talked about wiring all the way back through the hatch-door. My guess is there should be a wire already on the harness for the backup camera because the stock camera wires into the Nav HU (when it factory installed).

I just grounded the parking brake wires and my HU accepted that as sufficient... no more blocking video.

 

I think you'll have a different setup if you don't have the JBL system. One of the components I used (TATO) is entirely unnecessary if you don't have the JBL system, because the TATO is what communicates with the factory amp that comes standard with the JBL system.

If you're going to upgrade the non-JBL you might want to consider adding an amp and maybe replacing the speakers, from what I've read.