Use this article if…
Pick your symptom (one line): Black or “no signal” (reverse opens but you get no video) · Never switches off radio / maps · Picture wrong but not blank (rolling, tinted, scrambled, fuzzy), use Fix on this page.
- Use this overview article if: you want the MK4 camera fault overview, you've got a wrong or distorted image with video present, your camera drops out after bumps, you suspect a loose adapter, or you want the AHD/CVBS, trigger and LC76 / 28-pin context in one place.
- Don't start here if: the reverse screen opens but the image area is only black / blank / “no signal” → Reverse camera shows black screen.
- Don't start here if: reverse never opens a camera page (you stay on radio, maps or the last source) → No reverse camera showing when in reverse.
- Parking / trajectory lines missing but the video's otherwise fine → Parking guidelines missing.
- Not an MK4 headunit → Black / wrong picture (generic) · Cameras hub.
Quick answer
Match your symptom first: black or “no signal” with the camera page open goes to the black-screen guide, and no switch from radio or maps goes to the no-display guide. If your picture's wrong or rolling, cuts in and out, or you want the full adapter, trigger and format checklist, start here.
Problem
- Your reverse or extra camera won't switch on, or the picture's wrong.
Which article? Black / blank / “no signal” but you can still see the camera layout → Reverse camera shows black screen. Never leaves the previous source in reverse → No reverse camera showing when in reverse. Live picture but distorted (rolling, colours, interference): stay on this page and use Fix.
Symptoms
- Black screen when you select reverse, other sources are fine.
- The camera never switches, you only see the last source.
- Rolling, tinted or scrambled image.
- Works cold, fails after you hit a bump (intermittent).
Cause
- Your reverse trigger wire's missing or reading low, from a PWM tail-light tap or a bad ground.
- You've got an adapter harness, like a 28-pin conversion, partly unplugged or with a damaged pin.
- Trailer or loom grounds are sharing the reverse circuit.
- Rare: the camera body's failed while the radio's still good.
Fix Step-by-step
- Open camera settings, then set the format to match your camera: CVBS N for a factory or standard analogue camera, AHD 720P25 for a PVS AHD camera. Restart the unit after you change it.
- With the wheels chocked and the brakes set, meter the reverse input at the MK4 loom while you select reverse. You should see solid activation matching your diagram.
- Reseat every adapter shell and look for backed-out terminals.
- Swap camera inputs temporarily, where it's safe, to prove a specific port works.
- Clean the shared earth points if you tow with an aftermarket harness.
Notes
- Install wiring: How to wire cameras to the MK4
- No switch in reverse: No reverse display
- Black / wrong picture: Reverse black screen
- Picture OK, no parking lines: Parking guidelines missing
- Trigger theory: Reverse trigger wiring, AHD vs CVBS
- Harness power: MK4 harness
No multimeter?
- Safe checks without a meter: toggle AHD/CVBS to match your camera and reboot once, reseat every adapter shell, confirm the reverse input assignment in settings, then swap the camera feed to another allowed input to test the port (helper in reverse, vehicle safe).
- A multimeter is what you need for the step that proves the reverse trigger at the loom. Use it when the screen never switches, or when you think the trigger's marginal (PWM tails, trailer looms).
- If you can’t meter: finish the format and adapter seating first. For pure black with a camera page, use Reverse black screen. For no switch at all, use No reverse display. Then get an installer to test the trigger, or email PVS with the video plus adapter photos.
Still stuck? Send us these photos
- Vehicle: model, series and year.
- Short video: wheels chocked, brakes on, then shift into reverse twice. Show whether the UI switches and what the picture does.
- Screenshots: the MK4 camera format menu (AHD/CVBS) and the reverse input assignment / multiview page.
- Photos: every adapter shell or 28-pin conversion between the camera loom and the headunit, both sides, plugs latched.
- Camera: the brand or part number on the camera body / box if you can see it.
- Say which branch matches: black screen, no switch or wrong picture, so we don't re-route you in email.