I have two Blackvue installs and two A129 Pro Duo install under my belt in the last year. Not an electrician or a mechanic. Here's my two cents, FWIW:
Generally speaking, yes, if you want parking mode, you need a 3-wire kit.
One for ground, one (usually labeled BATT) that's always hot to run parking mode when the ignition is off, and one (usually labeled ACC) that's only hot when the ignition is on (car running) to switch the cam to normal driving mode when the cam senses power there.
The separate BATT and ACC wires are what gives the cam the ability to know when the car is running (or not) so it can switch between driving and parking modes.
There are some exceptions, one being an OBD-II power cable, which can handle all those functions in one wire plugged into the OBD port. I use one of these with one of my Blackvue installations because that vehicle has no fuse box inside the cabin (thanks, Dodge...). If you go this route, same rule from below applies: Use one specifically made to be compatible with your brand of cam.
There are lots of YT vids explaining the differences in hardwire kits and how to use them, how to use fuse taps, etc.
They say a smart man learns from his mistakes, but a wise man learns from the mistakes of others. To that end, some general rules of thumb:
- RTFM. Read the f$*^ing manual. For the cam and the hardwire kit. Do your homework BEFORE you start.
- Find the fuse box diagram in your vehicle owner's manual rather than trying to figure out the fusebox while staring at it and imitating a circus contortionist under your dashboard. Come up with a plan of attack from the comfort of your office chair before you head to the garage.
- Figure out which of the three different kind of automotive fuses your car uses and get the correct fuse taps before you start. Have extra fuses on hand so that when you drop the one that comes with the tap kit or the one from the fusebox that you're tapping into down the black hole behind an interior body panel, you're not at a work stoppage.
- If one exists, ALWAYS use the manufacturer-specific hardwire kit for your car. VIOFO makes one for your cam. I just used same to install A129s in my sons' cars not long ago, they work great.
- NEVER rely on wire color. Some companies have red BATT wires, other have yellow BATT wires. They should be labeled, always go by the label, not wire color.
- When running wires to the fusebox, pay attention to where your airbags are. Run wires alongside or behind them, never in front of them.
- Be careful about which fuses you tap into. Avoid airbags, computers (PCM, BCM modules, etc.) and the like. Go for the simple stuff, like cigarette lighters, accessory power sockets, heated seats, power windows, etc.
- Unless you have a brand new super high CCA battery, never select the lowest low voltage cutoff settings. There are plenty of charts floating around that will show you the correlation between battery voltage and health. At 11.8 volts - a typical lowest available setting, your battery is already nearly dead. Especially if it's already old and weak. If you're going to be a regular parking mode user, learning about battery health and charge states, and buying high-quality batteries are a must.
- This ties into the homework first thing above. Some car makes are weird in the fusebox. Honda is a good example. Things that you'd normally think are switched are hot all the time, things that you'd think are hot all the time aren't. Spend some time researching other people's installations in year/make/models similar to yours, and see if they had problems or actually posted what worked for them (got a 2010 Honda CRV, anybody? PM me, I'll sort you out). Doing this homework ahead of time will save you a lot of hair-pulling later, trust me. Also, a lot of modern vehicles will keep some circuits powered for a short period of time after you turn the car off, so a circuit you THINK is hot when the car is off really isn't. This even bites professional installers from time to time. In any case, once it's installed and everything seems correct, shut the car off, stay in it, and VERIFY that it transitions into parking mode like it's supposed to. Otherwise, you may be in for a nasty surprise after the car has sat for awhile...
- Once you've got the right fuse tap locations sorted out, RECORD that info somewhere and SAVE it! That way, if someone else starts mucking around in the fusebox later to install something else and pulls your taps, you don't have to try and figure this out all over again from scratch...
All in all, not difficult to do. Just do your homework first, be patient, and be prepared to troubleshoot if need be.
Oh and troubleshooting rule number one: if the camera's not working, plug it into a powered accessory socket with the wire it came with and check it. Nine times outta ten, it's a wiring error down to you picking the wrong fuse to tap into.
