Howto add a Reversing Camera to After-Market Radios in VWs (not OEM radios)

[bgennette]

A quick improvement for many VW based vehicles is an after-market all-in-one Radio, DVD, AUX in, Bluetooth, GPS unit. Look-alike units these days are (almost) a drop-in replacement with the facia being an exact match to the factory units and a vehicle specific plug fitted. Modern VWs have lots of data transmitted via a Controller Area Network (CAN), a vehicle specific CAN decoder is often included with the new radios to intercept and act on messages such as - turn radio power on/off, lights are on/off, reverse gear is/not selected, a door is/not open, air con is adjusted, etc.

There are often a few differences in the electronics between the original and the replacement radio, so it’s going to take a little planning to achieve a satisfactory installation. Common fixups –
· As the CAN decoder turns the radio on/off any external AUX power lead needs to be disconnected (usually Red).
· Most after-market radios have a single, unpowered radio antenna socket (Motorola shape) while the VW originals often have dual, powered inputs (fakra shape). A power injecting adaptor needs to be fitted with power taken from the ‘ANT’ control wire (usually Blue).
· The GPS antenna needs to be positioned outside any metal shielded parts of the body work.
· Auxiliary inputs need to be run while the radio is being installed.
· A reversing camera needs to have a video lead run from the camera to the radio.
· If your vehicle doesn’t announce ‘reverse gear is selected’ then a signal wire also has to be run to the radio (usually Orange or Mauve, a pinky/purple colour). This wire may also need to be disconnected from the CAN decoder.

There are already lots of write-ups for installing these so I’m only going to add my 2¢ to them with a how-to for adding a reversing camera.

Reversing Camera for VW (number plate light type)
Test that in your car the CAN decoder will switch the radio to camera input when reverse gear is selected. If NOT then a signal wire will need to be run with the video lead from the rear to the front of the car to attach to the Mauve switching wire. Note, lots of reversing camera video leads these days come with this extra wire in place.

First thing, find where the cables can be run. The sample vehicle here is a Golf Mk6, others will be similar. Behind the rear bumper is the rear frame, with a gap at the bottom. Wires can simply be dropped down from the number plate light holes and they will hang down onto the road. There is a grommeted hole in the floor for the number plate light wires; a few plastic trims need to be unscrewed/popped out to access it. For the rear-to-front video cable run it makes sense to use the side where you access the power for the camera (see later).

Just to keep everything together I used a leader to pull the wires through – this avoids the wires twisting, separating and getting caught up on hidden bolts, etc. Once the wire was run the camera was clipped into place.

In the Golf installation the camera end of the supplied cables was too short to reach inside, so the video and power lead extensions needed to be fed up (through new holes in the grommet) from the road side. The joined cables then need to be wrapped tightly for water proofing and security. The proximity of an exhaust bracket requires careful routing and fixing.

Next up is powering the camera ONLY when reverse gear is selected. Most modern cameras only use ~0.1A while reversing lights use >1.5A, so we can expect the reversing light circuit to be fused for ~5A leaving ample for the camera. Except VWs newer than 2008 don’t use fuses for most lights, they monitor the circuits and only switch them on (through transistors) when they are OK, but as the transistors are usually rated for 10A, this will still work. However future systems may detect the extra load as a fault and an alternate scheme may need to be found.

The easiest solution for now is to splice into the Reversing Light wire (usually Black with a Blue stripe), but there is another problem for vehicles newer than 2008 as VW uses this same colour for the white Reversing Light on one side of the vehicle and for the red fog light on the other side. Put your car into reverse with the ignition ON to identify which side the light is on.
Once you know which side your Reversing Light is on then you can remove some trim and run the wires to there and splice in for power AND ground (always Brown). Run the rear-to-front video (and signal) wire along this side too. There is almost always enough space under the door trims for a neat installation.

The video just plugs in to the rear of the radio. If required the signal wire needs to be connected to the video switching wire (usually Orange or Mauve, a pinky/purple colour), AND the wire needs to be cut away from the CAN decoder.
Test the installation before putting the trims back in place, but beware of some VW eccentricities such as the Golf Mk6 won’t turn on the reversing light while the rear hatch is open . . .