Thanks Blackforge. That's good to know. Probably working around the problem - more capacity is likely to mean the voltage doesn't drop as much - but if it works it's going to be an easier fix than getting Pioneer to admit this even happens by the sound of it. I'll get my plans for a replacement battery back on track and report back when I've got it tested. Got a particular battery in mind and have to tie in collecting it with a visit to family so it could be a while. Thanks for testing this and letting us know.

Gareth

Just a thought... If he did a battery swap, he disconnected all power to the unit, thus resetting it. Have any of you with this issue tried just temporarily disconnecting the battery?

I've unplugged and replugged mine many times where I've been adjusting brackets to get it to fit well. I've also disconnected the battery for a while when I tried to test the battery from my old car....and failed because the terminals were the other way round and the cables not long enough. On the plus side, I'd swear my mpg went up afterwards!

Prior to the battery swap, I had disconnected my battery multiple times while tweaking/moving my amplifier and wiring.  Also using the reset on the unit itself, etc to no effect.

I can confirm it starts up every time now since I've put in the new battery.  It is an almost 3 year (440CCA?) vs brand new (850CCA) battery though, heh.  Though I had seen startup hesitations/long cranks intermittently in the past.

As for better gas mileage, the ECU does get reset if you leave the battery disconnected long enough.

I have a 4100NEX and a Subaru WRX 2015 with the same issue. Im pretty sure it's not a timing thing, like someone suggested, but the battery swap that Blackforge did, seems to hit the nail in the head. I will buy a battery tomorrow and report back with my results. 

Thanks to all and to Blackforge. 

Dude im having the same exact problem with my 4100nex.  good god I thought it was going crazy.  when I get in my car in the morning and turn it on its just stays at black screen for about 45secs to a minute then it boots up like normal. I install professionally and I cant seem to figure out whats wrong with the damn thing.  I have also swapped it with another unit and it does the same thing.  I have a 2012 scion tc push start by the way. 

I don't know if you found a fix yet but I did. I work at best buy as a installer the crazy thing is I worked on both cars people talked about the brz and the forester. Both had the same issue you guys mentioned. So what I did was wired the accessory power from the radio straight to the vehicles ignition wire fuse box

By the way one car had the 8100 and the other had the 4100

I will have my installer do this. Thanks so much Mike!

Hi everyone, luckily I found this thread. I also have a 2015 WRX and a 4100nex. Same issue. Sometimes it starts up immediately, sometimes it gets no power at all for x amount of time before turning on. It is very random. I noticed a lot of us have Subarus or gt86( frs may have subaru parts). I think it has to be something related to Subaru either the battery they use or how the ignition system works. Btw, I do not have push start.

I think it's some kind of timing issue that causes the problem - possibly interrupting the resume from hibernate the unit does at the wrong time....but I'm guessing after reading g bits of the development thread.

Pioneer (at least in the UK) don't seem to care. I have spoken to them several times and they eventually said to email them. I know they received the second email as I got a read receipt but they have not replied.

The stock battery is supposed to be quite weak in the BRZ/FRS/GT86 and some people have reported good results by replacing it with something with more oomph. Traces I took do show the voltage dropping to 5 or 6 volts while the engine starts. I've not tried replacing the battery yet as I've had other issues with my car to deal with first.

As a workaround you can try turning the key to position 1 or 2, wait until the radio screen lights up and then start the engine. It works every time in mine....but it is an irritation.

this is a common issue with nex units.  i have a scion tc rs7 push button and mine does the same thing.  i just put it on accy before starting the engine and it works 100% of the time.  

I have a Subaru Forester and had the same problem until I changed the battery.  Factory battery was only 390CCA.  Swapped for a 690CCA battery and the radio starts fine 100% of the time. ​​​

Just thought I'd feed back on this.  I've finally got hold of a new battery - specifically an AtlasBX AGM AXD26R.  Seems to have fixed (read: worked around the problems that Pioneer don't want to admit exist) the problem.  I'm not sure whether this is because the battery is AGM (capable of delivering a higher current) and hence doesn't allow the voltage to drop as much while the AVIC is coming out of hibernation or whether any larger battery would have done the job - this is a 75Ah vs the 48Ah that Toyota fitted.  It JUST fits the stock battery tray     Now if I could just figure out how to sort out the AVIC not remembering which song it was playing and what the icons in the quick launch were, I'd be happy

I have a similar issue on my 8100, sometimes when I start my car the unit's buttons light up but the screen doesn't light up nor does the iPhone plugged start charging from the HU. If I turn the car off and then back on, there is about a minute delay but then the unit will turn on and boot up. After that booting up is pretty quick until the issue surfaced again and repeats exactly the same.

Thank god I found this thread. I don't have any solution but I want to share what I do know about this stupid issue.

I have a 2014 Sienna Limited Model and got a AVIC-8100NEX, I started noticing this issue after 1 month of usage.

I thought the stock battery of the car went bad so I replaced it with a new one from Costco (slightly more juice) after reading up on someone claiming it potentially battery related. Initially I though my Toyota battery was crap (because I recall it dying even after sitting for barely 1 week, etc)

Right after the new battery install, it seemed to have fixed the problem. So I thought. Soon later, this issue happened again. I can confirm that replacing a new battery DOES NOT fix this issue.

A couple of weeks ago I left my car at the body shop for repair and it seemed like when I got it back yesterday that issue went away, when I boot up the car (PUSH START - Holding down brake pedal) the unit booted up right away. Next thing I knew, this problem came right back.

It almost always does it now...80%-90% of the time. And like other people say, the work around method for me so far is to not get too much into a hurry and start the Engine without pressing the Engine Start button once (to get it into ACC mode), wait and then Start the Engine (by holding the pedal). - This is very freaking annoying since all my push start cars I just go in and start the car right up. I don't ever see a benefit for me to turn it on ACC mode (which requires a few seconds) then start the engine (2 step process that can be done in 1)

I have tapped the red power lead into other places behind the headunit already, DOES NOT help this situation.

What's worst with this top of the line headunit is I've had other issues such as:

1. Out of no where I'd boot up with no Audio....until 3 car rides (couple of different start up with 30 mins upto hours duration in between) before it resets and audio just comes back magically. Imagine how shitty this could be, I could be possibly find myself in a long car ride journey with no music when Music is the only thing keeping me going.
2. Watching M4V, AVI movies on a SD card, sometimes it'd crash and then no videos would show up and it'd never reset itself back until I restart the car. (Image how much of a pain in the butt that'd be if I'm on the freeway in a road trip - I'd have to pull over to a stop just to fix/reset this?)

Enough venting about other issues. My next attempt is to use those hop on piggy back fuse adapter, taking power from there. But I'm pretty sure that's not going to work either.

This is so annoying....because I use my backup camera all the time to drive my minivan. And if 1 time I accidentally forgot to startup the car using the 2-step process (say, if i'm distracted and I want my A/C to kick on right away by booting my car right away), I could potentially be waiting for 45 seconds - 1 min + sitting in the parking lot not having back up camera. THAT IS SO STUPID!

I'm having the same issues with a brand new AVIC8200-NEX. I was about to exchange it with a new one but now that I read all of this I don't think that would help. I think it's totally unrelated to the battery. It all seems to be the unit getting "confused" during initial startup. Most of the time the unit turns on within seconds, but sometimes it is blank for a good minute. One time it stayed off for an entire 30 minute drive (and I pulled over to turn the car off and back on in the middle). After disconnecting and reconnecting the negative battery terminal that got it working again that particular time. It's a huge pain and if it happens before a 10 hour drive I will be furious. The delayed start is definitely annoying when I am about to go in reverse and don't have the backup camera.

Also potentially related: the unit came on, but only the button beep sound worked. None of the sources' sound worked (mute wasn't on and the volume wasn't at 0 or something stupid). No function played sound (not the radio, bluetooth, ipod--nothing). It recognized my voice because I gave it a Google navigation command, but I couldn't hear it respond, although it loaded maps. Later, a similar thing happened but only the front left speaker worked. The rest of the time I've had the unit all speakers worked just fine. All of this shows that it was definitely not a connection issue, but rather some internal/firmware issue. I believe these Pioneer units have some problems that are not being addressed.

Last week this started happening to my AVIC4200-nex with datalink maestro installed. After checking all wire connections and making sure the unit was getting power I could not find anything wrong. Did master resets on radio and maestro unit, and even re flashed the maestro. 

On the radio settings, I was checking in the car features maestro setting and came across accessories on during crank and that was not turned on. Changed it to on and the radio comes on every time when I start my car using the push button.