Use this article if…
- Use this article only on MK4 when selecting reverse does not open a camera page at all, the headunit stays on radio, maps, or whatever source was already active (no obvious switch to reverse video).
- If a camera layout appears but the picture is black or “no signal,” that is not this article - use Reverse camera shows black screen.
- Live picture but missing parking lines only → Parking guidelines missing.
- Wrong or rolling picture (video visible, not blank) → Camera troubleshooting overview.
- Trigger theory and tails: Reverse trigger wiring.
Quick answer
When reverse never appears at all, check the reverse trigger at the MK4 harness with a meter and confirm the correct physical camera input is assigned as “reverse” in settings.
Problem
- Selecting reverse does not open the camera view on the MK4.
Symptoms
- You select reverse and the headunit stays on radio/maps - no switch to camera at all.
- If the UI does switch to the camera page but the image is black or “no signal,” stop here and use Reverse camera shows black screen.
Cause
- Reverse trigger not reaching the MK4 (wrong tap, PWM tail feed, trailer loom issue).
- Camera assigned to wrong input in settings.
- Adapter harness not fully latched after install.
Fix Step-by-step
- In a safe, chocked setup, meter the reverse trigger wire at the headunit harness while an assistant selects reverse - compare to your camera wiring plan for “on in reverse.”
- Open camera settings and confirm which physical port is designated reverse.
- Reseat every adapter (e.g. 28‑pin conversions) and verify no pin is bent.
- Temporarily feed a known‑good 12 V test to the reverse sense input only if your procedure allows - proves the radio responds.
Notes
- Install: Wire cameras to the MK4
- Camera page but black picture: Reverse black screen
- Overview: Camera troubleshooting
- No power at camera: Camera no power
- Trigger theory: Reverse trigger wiring
No multimeter?
- Safe checks without a meter: Vehicle chocked, brakes on - with a helper, shift reverse while you watch the screen: confirm whether the UI ever tries to switch; in MK4 camera settings, assign the correct physical input as reverse; re-seat adapters (28‑pin etc.) and recheck tails against the wiring plan photos - look for loose shells, not “almost clicked.”
- A multimeter is required to prove the reverse trigger wire at the headunit harness actually changes state in reverse versus your diagram (PWM tails especially).
- If you can’t meter: Use a qualified installer for a trigger verify, or email PVS a short clip (reverse selected) plus a menu screenshot showing input assignment - do not probe live needles without training.
Still stuck? Send us these photos
- Vehicle: model, series, and year.
- Short video: from a safe, chocked setup - select reverse twice while the screen stays on radio/maps (show no camera switch).
- Screenshot: MK4 camera / input settings showing which physical RCA is assigned as reverse.
- Photos: adapter harnesses (28‑pin, LC76 conversions, etc.) latched at the radio; reverse trigger tap point only if easily visible without stripping tape unsafely.
- List: whether any camera ever appears on another input on the same headunit.