52 Plate C3 Rear Light Cluster Wiring.

Fitting a rear facing camera to my C3 and can't find a wiring diagram to determine which wire is switch and which is live (Reverse Lamp). Closest I can find is a 2007 diagram no where seems to have one for 02/52. Cheers.

Looking for something like this for reference. This is from a newer C3. Don't want to risk wiring it backwards using the wrong diagram though.

It would be a very simple voltage test to find the wire. You could even trace it back from the lamp carrier in the rear cluster.

Haynes says its pin 4 for the 12v supply from the BSI and pin 1 being earth on the lamp carrier plastic tray on a 2002 which does differ from your later model version diagram you attached (assuming its IS showing the reversing light wiring)

As a side note, the earth can have trouble on the connector to the rear light cluster, there is a modification here.

Firstly thanks for the quick reply. I was trying to trace from the cluster itself, the wires were connected to the same pins, just wanted an older diagram to make sure they were still the same way around.

I could figure out which wires it is through testing but I have no way of working out which wire is constant and which wire is switch. How would I differentiate the 2 wires?

okaythen wrote:I have no way of working out which wire is constant and which wire is switch.

Switched will be the one that lights the reversing light with 12v and I would assume to power the rear camera.

I don't think you will find a constant 12v at the rear light cluster, they are all switched.

There is a constant earth (0v) that is common to the car.

okaythen wrote:How would I differentiate the 2 wires?

There aren't 2 live ones. One is earth and one is a switched 12v.

Earth is easy to spot, its common to all of the lamps.

okaythen wrote:I was trying to trace from the cluster itself, the wires were connected to the same pins, just wanted an older diagram to make sure they were still the same way around.

OK,

Arfur Dent wrote:Haynes says its pin 4 for the 12v supply from the BSI and pin 1 being earth on the lamp carrier plastic tray on a 2002

(the lamp carrier plastic tray is part of the rear cluster).

That makes sense, thanks for the explanation. I'll have a play tomorrow hopefully since it's raining at the minute.

Thanks again

If you was wondering what my wrong assumption was about the 2 wires, I was assume 1 wire was always supplying 12v to the bulb (to all the bulbs) and the switched would 'complete the circuit' when the car's in reverse.

okaythen wrote:If you was wondering what my wrong assumption was about the 2 wires, I was assume 1 wire was always supplying 12v to the bulb (to all the bulbs) and the switched would 'complete the circuit' when the car's in reverse.

I see, with a common earth system as in nearly every car at 2002/52 you will have earth or 0v common to lamps and a switched 12v live/ +ve that comes from a BSI, switch or control circuit of some sort. (BSI on the C3).

okaythen wrote:That makes sense, thanks for the explanation. I'll have a play tomorrow hopefully since it's raining at the minute.

Great, if you get it installed, it would be interesting to see some pictures. If you wanted to share how you did it and what its like when working, you are welcome to put a post in the 'tips' section (here) to help others thinking about doing the same upgrade

Connecter a reverse sensor kit and spliced in at the rear lights.
The reverse light lead is a switched 12v
Worked fine for years and then I noticed reverse light and sensors not working. Checked fuse and all good.
I disconnected the reverse light fitting and the sensors started working again.
Even without a bulb in the fitting the sensors do not work when the fitting is connected.
Ordered a secong hand fitting over eBay and awaiting delivery.

davidandpaula wrote:Even without a bulb in the fitting the sensors do not work when the fitting is connected.
Ordered a secong hand fitting over eBay and awaiting delivery.

Sounds like the sensors have a bad connection?