Support for the PVS 12.1″ MK4
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Display & System
Connectivity & Phone Mirroring
Internet & Navigation
Radio & Media
Audio Outputs & Processing
Cameras & Video
Vehicle Integration
Power & Wiring
Fitment & Warranty
In the Box
Tutorial Videos
FAQ
Installation
Will the MK4 Fit My 70 Series? What’s in the Box?
Before removing the factory radio, confirm the 200 mm late-2009+ 70 Series opening and unbox harness, fascia, mic, and hardware - the narrow early steel-dash radio slot is not MK4-compatible, so photograph the opening if you are unsure.
How Do I Remove the Factory Radio and Fit the MK4 Fascia?
Clips that will not bite or a gap along one edge on MK4 usually means trim order is wrong or the loom is bunched behind the stack - re-offer the assembly square, relieve harness bulk, then clip evenly before final screws.
Where Do the MK4 Power and Speaker Wires Go?
Dead screen or dead speakers right after plug-in is most often wrong constant, ACC, or earth versus the PVS LC70 diagram, or a plug not fully latched - follow only that loom sheet and re-seat every terminal before assuming a faulty unit.
The Supplied Harness Doesn't Match the Plugs in My Dash
Nothing is missing from your kit. Our harness ends in the factory headunit plugs for your vehicle, so if nothing mates, the factory plugs have been removed or cut out by a previous aftermarket stereo install. Either unplug that old loom to get back to them, or have an auto electrician reinstate the factory plugs.
First Time on: Wi‑Fi, Updates, and Microphone
First-boot pain is usually Wi-Fi (join or a stuck Wi-Fi screen - hotspot, forget network, then real internet), wrong date/time, Google sign-in in a bad webview (Skip and add under Settings), or a mic test before the plug is seated - Skip if allowed, then use PVS firmware only.
Phone Connectivity
CarPlay or Android Auto Keeps Dropping (Wireless)
Unstable wireless CarPlay or Android Auto on MK4 is usually repaired by pairing from the headunit menus with a known data USB cable ready, forgetting stale Bluetooth entries on the phone, and stripping non-essential BT gadgets for one test drive.
CarPlay Won’t Connect the First Time
First-time CarPlay on MK4 usually needs a clean wired pass: Apple-certified data cable straight into the unit, iPhone CarPlay list cleared for stale cars, phone unlocked with prompts accepted - then add wireless only after one good wired session.
My Phone Won’t Pair (Bluetooth, CarPlay, or Android Auto)
Phone connection problems clear fastest by deleting the MK4 from Bluetooth and from CarPlay/Android Auto on the phone, rebooting both devices, and pairing again from the MK4 wizard with a known-good data cable.
CarPlay Keeps Disconnecting
Wireless CarPlay that drops mid-drive is usually repaired by forgetting the car in iOS CarPlay settings, deleting the MK4 from Bluetooth, rebooting phone and unit, and pairing cleanly - then testing with a short Apple-certified cable.
CarPlay Keeps Taking Over Wi‑Fi (Starlink Issue)
When CarPlay fails because the iPhone keeps jumping Wi-Fi networks, use wired CarPlay for projection and leave the phone on Starlink (or another router) for data - or turn off auto-join on the headunit Wi-Fi.
Android Auto Not Connecting
Android Auto that will not start is usually the app, cable, or stale pairing. Update Android Auto, use a proven data USB-C cable, turn off aggressive battery optimisation for AA/BT, and pair again from the headunit.
External Microphone Issues (Calls / Voice)
External mic issues on MK4 are usually placement and wind, a half-seated mic jack, or Android/CarPlay refusing mic permission - reseat the plug, reposition per first-boot guidance, retest with a voice memo parked, then re-allow microphone for phone projection apps.
Internet & SIM
No Internet on the MK4 (Wi‑Fi, SIM, or Hotspot)
Wi-Fi that shows connected but loads nothing is frequently a captive portal, wrong MVNO APN, or a SIM tray that is not making contact - open the MK4 browser to finish camp logins, re-seat the SIM power-off, and paste APN details exactly as the carrier publishes.
GPS Inaccurate, Slow Lock, or Weak Signal
Weak or wrong GPS on the MK4 is usually location mode set to low accuracy, missing permissions for maps or Play services, wrong automatic time, or the vehicle blocking sky - turn on high-accuracy location, fix the clock, grant permissions, then verify with a short drive in the open.
Cameras
How Do I Wire Reverse and Extra Cameras to the MK4?
MK4 camera installs go wrong fastest when AHD/CVBS does not match the camera or reverse sense comes from a PWM tail tap - set format to the camera, meter trigger at the MK4 loom, and fully latch any 28-pin style adapter. Want a camera running full time, not only in reverse? The reverse input only shows while the car is actually in reverse, so wire that camera to the aux video input, the yellow RCA on Harness A,…
Reverse Camera Shows Black Screen
A reverse screen that opens but stays black is very often AHD versus CVBS mismatch. Toggle the camera format in MK4 settings, reboot once, and test again in reverse.
No Reverse Camera Showing When in Reverse
On the MK4 the reverse trigger is pin 5 (BACK_CON) on the 16-pin main plug, and the wire is pink. On a factory Toyota camera there is no trigger wire to connect, because reverse already arrives on Connector 3. Confirm the correct physical camera input is assigned as reverse in settings before chasing a wiring fault.
Reverse Camera Won’t Come On, or the Picture Is Wrong
Triage first: black or "no signal" with the camera page open goes to the black-screen guide; no switch from radio/maps goes to the no-display guide; this overview covers wrong or rolling pictures, intermittent faults, and the full adapter/trigger/format checklist.
Reverse Parking Guidelines Missing
Missing parking lines on MK4 usually means the camera simply doesn't output overlays the unit can draw - or the feature is off in camera settings - enable guidelines in the MK4 menu, confirm the camera actually supports lines, and expect some factory Toyota overlays not to transfer to aftermarket heads.
Audio
No Sound from Speakers
Most "no sound" cases are volume/mute on the MK4, loose speaker plugs, or - when a factory amplifier is retained - the amp not waking because the turn-on or integration leads are wrong. Check those before swapping hardware.
Bluetooth Connects but No Audio
Bluetooth that pairs but stays silent is often media audio toggled off on the phone profile or volume at zero on the phone while projection is fighting for audio. Turn media audio on and raise volume on both phone and MK4.
Steering Controls
Steering Wheel Buttons Don’t Work with My MK4
Factory LC70 wheel audio keys use the OEM Android steering-learn path; PVS aftermarket wheel kits need the bundled wireless receiver and its learn sheet - a bare MK4 does not ship that receiver, so match your wheel type before chasing settings.
Steering Wheel Controls Not Responding
Non-working wheel buttons on the MK4 are usually a learn/pairing issue, not a failed radio. Open steering-key learning in Android settings and complete the wireless kit learn sequence from your wheel instructions.
Troubleshooting
My MK4 Won’t Turn On, or It Keeps Restarting
A unit that will not power up is most often low battery under load, a blown fuse, or ACC/constant/earth not correct at the harness. Meter the radio plug against the PVS wiring diagram before opening the radio.
MK4 Firmware & Software Updates (PVS)
Check build under Settings → About, only flash USB packages PVS gives you for your MK4, keep the engine running and the stick in until the unit reboots itself, then key-cycle - never flash random Android images or pull USB mid-update.
USB Drive or Device Not Recognised
When the MK4 ignores USB storage, rule out charge-only adapters and NTFS-only sticks first - try a small exFAT/FAT32 flash drive directly in the port with shallow folders, clean the socket, and avoid unpowered hubs.
Battery Drain after MK4 Install
Extra drain on the vehicle's 12 V starter battery after MK4 is most often ACC and constant swapped or accessories piggy-backed on the radio feed - meter parasitic draw at the vehicle, re-check the harness against the PVS diagram, and unplug USB gadgets from the headunit overnight to find the thief.
Headunit Has Power but Won’t Turn On
If lights come on but Android never fully boots, disconnect all USB add-ons, confirm both constant and ACC are correct on the main harness, and allow a long first-boot wait once before assuming hardware fault.
Unit Resets or Freezes
Random reboots or freezes are often unstable supply voltage or a bad USB device. Unplug every USB accessory from the MK4 and check battery voltage under real load before looking for software causes.
How-To Guides
How to Trim the Dash Tabs When Fitting a 9 Inch Head Unit
A 9 inch unit that will not stay in and keeps popping back out is almost always the four plastic tabs in the dash opening, not a faulty unit. They hold it proud, so the lower clips never reach far enough to engage. Check the lower clips are intact, then cut the four tabs flush with side cutters. It is the same four tabs on the MK3 and the MK4.
How to Install an App on an Android Head Unit
The MK4 runs Android 13 with the Google Play Store on it, so you install apps the same way you would on a phone. Sign in to a Google account first. Almost every "Play Store will not work" report comes back to that step or to old software.
How to Pair a Bluetooth OBD2 Adapter to an Android Head Unit
Plug the adapter into the diagnostic port, then pair it under Settings and Bluetooth on the head unit BEFORE you open any diagnostics app. An app cannot see an adapter the unit has not paired, and that is the order almost everyone gets wrong.
How to Install and Set Up Torque Pro on an Android Head Unit
Pair your Bluetooth OBD2 adapter under Settings first, then install Torque Pro from the Google Play Store and point it at that adapter. Torque cannot find an adapter the head unit has not already paired.
How to Switch Between Apple CarPlay, Android Auto and HiCar
The unit opens in Apple CarPlay mode by default. To change it, open the PVS Link app, tap the four square apps icon, and select Android Auto or Huawei HiCar. A phone that pairs but never opens anything is almost always still in the wrong mode.
How to Get an Android Head Unit Online
Three ways. Put a SIM in the card slot and make sure the 4G antennas are connected, join a WiFi or Starlink network under Settings and WiFi, or turn on the hotspot on your phone and join that. The Play Store and any online app needs one of the three.
How to Run CarPlay at the Same Time as Starlink or a Hotspot
A phone WiFi radio can only be on one network at a time, so a phone doing wireless CarPlay cannot also stay on Starlink or another hotspot. Plug the phone in and run CarPlay wired over USB instead. Wired CarPlay does not use the phone WiFi at all, so the phone stays on the other network.
How to Set Up Hands-Free Calling and Fit the Microphone
Open the Bluetooth app on the head unit, tap Search, select your phone and press Connect, then confirm the pairing on both. An external microphone is supplied and it plugs into the 3.5mm socket on Harness A. Where you mount it decides how you sound far more than any setting does.
How to Set Up Navigation and Offline Maps for Areas with No Signal
The unit has its own GPS receiver, so it knows where it is with no phone and no mobile signal. What it cannot do without a connection is download a map it has never seen, so install the app and download the areas you are heading into while you still have WiFi.
How to Choose the Right Audio Output on an Android Head Unit
The unit has four speaker channels from its internal amplifier, 5.1 channel RCA pre-outs at 4 volts RMS, and two digital outputs. Which one you use depends on what your amplifier or processor will take.
How to Connect an External Amplifier to an Android Head Unit
Front pre-outs are the white and red RCAs on Harness A, pins A4 and A6. Rear pre-outs are the white and red RCAs on Harness C, pins C3 and C4. The amplifier turn-on lead is the blue wire on A1. Harnesses A and C ship with the unit and only get connected if you are running an amplifier.
How to Add a Subwoofer to an Android Head Unit
The subwoofer output is A16 on Harness A. It breaks out to two green RCA plugs on the harness, both carrying the subwoofer signal. It is a dedicated output, so it does not use either of the front or rear pre-out pairs. The turn-on lead is the blue wire on A1, the same one an external amplifier uses.
How to Connect a DSP Using the Digital Audio Output
There are two digital outputs. The optical SPDIF socket is on the rear panel of the unit, and a coaxial SPDIF output sits on C6 of Harness C on a brown wire. Use whichever one your processor has an input for. Neither is needed for a standard install.
How to Set Up a Reverse Camera on an Android Head Unit
On a factory Toyota camera there is no trigger wire to connect at all. The camera plugs into Connector 3, and the video comes back out on Connector 10 as a yellow RCA which has to go into the reverse camera input on Harness F. An aftermarket camera is the only case with a trigger to run.
How to Add a Second Camera for a Trailer or a Front View
A standard MK4 has two video inputs. Reverse uses the camera input on Harness F and switches automatically. The second one is the auxiliary video input on A18, the yellow RCA on Harness A, and you select it yourself from the source list. Reverse still takes over the moment you shift into reverse.
How to Program Steering Wheel Buttons on an Android Head Unit
Open the SWC app, select the function on screen, press the matching steering wheel button once, repeat for every button, then press Save. Press each button once. Holding it is only used when you are assigning a long press secondary function.
How to Update the Software on an Android Head Unit
Format a USB drive to FAT32, copy the update file onto it, plug it in with the ignition on and follow the prompt. The drive has to be FAT32 and the capacity does not matter. The update performs a factory reset, so apps reinstall and the Google account has to be added again afterwards.
How to Factory Reset an Android Head Unit and What You Lose
Go to Settings, then System, then Reset. It wipes every app, every login, your Bluetooth pairings and any settings you changed, and gives you back the unit as it left the factory. Set the clock before you try to sign in to Google afterwards, or the sign in fails with an error that never mentions the clock.
How to Check Whether a Head Unit Is Draining the Battery
The unit takes two supplies: a permanent one on pin 2 that holds settings and the clock, and a switched accessory one on pin 3 that turns it on and off with the key. To find out whether it is the cause, measure the current draw at the fuse for the head unit circuit with everything switched off.