Towbar Wiring

[PoorPaulus]

Hi everyone,
I've fitted a towbar to my 2008 W221 S320 CDI and I'm struggling to find any wiring details for the rear lights and parking sensors so that I can wire it in.

I've had a good look around, but I've failed. Can anybody help with this?

P.

 

[EmilysDad]

Assuming your car is CAN bus, would it not need a dedicated loom?

 

[PoorPaulus]

To be honest, I have no idea.
On every towbar I've fitted before, I have simply spliced in to the appropriate wire on the rear lamps. The MB loom is the same price as the metalwork that I've fitted, so I've got a generic 7-pin kit that I've successfully fitted to my last two cars, both, I presume, had a CAN bus as they were relatively modern cars.

 

[PoorPaulus]

I'm still looking...

 

[Dave C250]

You can use a standard loom, but you will also need a bypass relay.

 

[turbopete]

as Dave above. ive used the bypass relays in my last 2 cars without issue.

 

[PoorPaulus]

Yup, I appreciate that. I just need to know what colours do what on the back of the taillights and parking sensors to I break in to the correct wires.

 

[M80]

I can give you the colours from a 2005 C class, but there's a good chance the colours on different models will vary.

1. N/s flasher - black / white,
2. Fog - green / white,
4. O/s flasher - Black / green,
5. O/s tail - Mauve / red,
6. Brake - Black / red,
7. N/s tail - Mauve / black,
R. Reverse (n/s) - Grey / blue.

The numbers relate to the 7 pin plug positiion.

Fuse 17 in the rear left cubby is the dedicated fuse for the relay (to protect trailer faults from affecting the cars lights).

To confirm you might pierce the insulation to the conductor with a drawing pin and use a meter to check for 12 volts.

 

[PoorPaulus]

That's a good start. Thanks for the help.