Support Headunits
Headunits knowledge base for PVS systems (including 9" MK4 on LC70). Installation, phone, internet, cameras, audio, steering, and power fixes - organized as subcategories below.
General hubs (troubleshooting-first): Cameras, Steering wheels, Audio.
Reverse camera - pick the right guide: Black or “no signal” when reverse opens the camera page · No switch from radio / maps in reverse · Wrong / rolling picture (overview).
Top issues
Match your symptom to the line, then tap - each row opens the main guide (related links are in-page).
- Google Play won't sign in, or the head unit keeps rebooting Almost always old software. Install the latest update for your unit from this page, then set the correct time zone and date and time (a wrong clock blocks Google sign-in). MK3 units that keep rebooting need the latest MK3 software update too.
- Won’t turn on - totally dead or stuck booting? No backlight or logo at all: this guide. Backlight/logo but black screen or boot never finishes: open “Headunit has power but won’t start” under Troubleshooting below.
- No sound from speakers FM/USB/Bluetooth all quiet, or only one source - mute, harness, factory amp retention; Bluetooth-only silence → Bluetooth connects but no audio (Audio).
- CarPlay or phone - won’t connect vs drops while driving? Never pairs or stuck “connecting”: this guide. Worked then disconnects on the road: “CarPlay keeps disconnecting” under Phone Connectivity below.
- Reverse camera - black screen or “no signal”? Opens the dedicated black-screen guide (AHD/CVBS, cable). If reverse never leaves radio/maps, use No reverse camera showing when in reverse under Cameras. Rolling or wrong-colour picture (video present): camera troubleshooting overview.
- Steering wheel buttons not working Keys dead after install - learn/pairing and re-seat SWC plugs; never set up the wheel? Start with Steering wheel buttons with MK4 under Steering Controls.
Installation
-
Will the MK4 fit my 70 Series? What’s in the box?
Dash compatibility, kit checklist, and prep - before you pull trim.
-
How do I remove the factory radio and fit the MK4 fascia?
Swap the factory stack for the PVS panel without pinching wiring.
-
Where do the MK4 power and speaker wires go?
Toyota harness: constant, ACC, earth, and speakers - follow the PVS diagram.
-
First time on: Wi‑Fi, updates, and microphone
Wizard, network, official USB firmware, and mic placement.
Phone Connectivity
-
CarPlay or Android Auto keeps dropping (wireless)
Pairing, good cables when needed, and fixing unstable wireless.
-
CarPlay won’t connect the first time
Initial wired CarPlay setup: cable, iPhone CarPlay list, permissions.
-
My phone won’t pair (Bluetooth, CarPlay, or Android Auto)
Forget/re-pair, cables, and phone settings.
-
CarPlay keeps disconnecting
Mid-drive drops, iPhone sleep, and wireless stability.
-
CarPlay keeps taking over Wi‑Fi (Starlink issue)
iPhone auto-join vs Starlink or camp Wi‑Fi on the MK4.
-
Android Auto not connecting
USB cable, AA app, permissions, and wireless quirks.
-
External microphone issues (calls / voice)
Placement, jack seating, wind noise, and projection mic permissions.
Internet & SIM
Cameras
-
How do I wire reverse and extra cameras to the MK4?
Inputs, factory LC76 paths, AutoChimp 28‑pin, reverse trigger.
-
Reverse camera shows black screen
Camera page opens but no picture or “no signal” - open this before the overview when the symptom matches.
-
No reverse camera showing when in reverse
Stays on radio/maps in reverse - trigger, input assignment, adapters. Black image after switch → Reverse camera shows black screen.
-
Reverse camera won’t come on, or the picture is wrong
Overview when video is wrong (rolling, tinted) or you need the full checklist - not pure black (use Reverse camera shows black screen first).
-
Reverse parking guidelines missing
When video works but overlay lines don’t - camera capability vs MK4 settings.
Audio
Steering Controls
Troubleshooting
-
My MK4 won’t turn on, or it keeps restarting
Battery, fuses, earth, and harness voltage - full power pass.
-
MK4 firmware & software updates (PVS)
Check build, when an update makes sense, safe USB rules, when to contact PVS.
-
USB drive or device not recognised
FAT32/exFAT, hubs, charge-only leads, and port cleaning.
-
Battery drain after MK4 install
ACC vs constant, parasitic draw, and USB accessories on the radio feed.
-
Headunit has power but won’t turn on
Volts present but black screen or stuck boot.
-
Unit resets or freezes
USB load, voltage dips, rogue apps, and heat.