Not sure if the Vectra is different but to wire a Zafira A model towbar, first check if yours has a pinky/purple cylindrical connector inside the O/S (that on the right hand side as you look at the back of the car) cubbyhole. If so then you can use a dedicated plug in zafira towbar wiring kit, available on ebay for between £30-£40, which will save you lots of time and hassle. If, like my Zafira, yours does not have this connector, then you will have have to do it the old fashioned way, by breaking into the wiring loom. Assuming you do have to break into the loom, you will need to remove a few things to get access...Get yourself a T50 Torqx bit and remove the upper rearmost seatbelt bolt on the left hand side (the N/S), then pull off the centre and rear upper plastic window trim by hand. Then get yourself a T25 Torqx bit and unsrew all the screws you can see the hold the lower plastic trim to the car. Hinge the rear of the lower trim towards the other side of the car so its out of the way. Once you have wired up the 12N socket on the towbar in the correct fashion, (see here):
http://www.towingandtrailers.co.uk/shop/132/133/142/
You now need to run your 7 core cable into the car. As you look at the back of the car you need to locate the rubber grommet under the rear cross member to the left of the end of the exaust. Prise it out carefully with a small flathead screwdriver then carefully cut the end off the grommets central "teat", without damaging the rest of the grommet. Slide the grommet onto the cable the correct way round (it should be a tight fit as it need to keep water out later) then tape the end of the 7 core cable to a length of steel coat hanger wire. Use this to feed the wire up through the hole towards the lighting well which is behind the left hand lighting cluster. Use your right hand to feel for the end of the cable (you might have to move the foam soundproofing out of the way to get your hand down far enough). You should be able to pull it up into the lighting well. Pull the rest of the wire through and when it cant go anymore slide the grommet on the cable back to hole and squidge it back in to seal the hole. You can use a cable tie or two to secure the cable along the towbar...You need to keep it away from the exaust. Do not cut off the excess 7 core cable , incase in ends up too short. Its better to roll up the excess and secure it with a cable tie or two. Some people use Scotchblocks to connect the wiring but I prefer crimp connectors as they are more secure and much slimmer in profile so they make the job a lot neater...Plus they are very cheap! You will need to connect up your audiable indicator buzzer too.
The yellow wire from the buzzer connects to the yellow wire on the 7 core cable, the green wire from the buzzer connects to the green wire on the 7 core cable, the white wire from the buzzer goes to earth and that leaves a yellow with black stripe wire which connects to the left hand (N/S) indicator and the green with a black strip wire which connects to the right hand (O/S) indicator. Now you need to unplug the 6 pin connector going to back of the left hand light cluster.
Hold the connector with the securing catch upwards and facing away from you and with the wires towards you...The pins are numbered 1-6 from left to right. Pin 1 is the left hand tail light (black and grey wire), pin 2 is the stop/brake light (black and yellow wire), pin 3 is the left hand indicator (black and white wire), pin 4 you don't need to worry about, pin 5 is the fog light (blue and black wire and pin 6 you don't need to worry about again. Cut the relative wires about 2-3 inches back from the connector, don't do them all at once or it will end up like spaghetti junction. Push the stripped end (you only need to strip off about 8mm of the insulation) of the yellow and black wire from the buzzer and one of the stripped ends of the black and white into one end of a blue crimp connector together, and crimp that end of the connector securely. Push the other stripped end of the black and white wire into the other side of the crimp connector and crimp that securely too...That's your left hand indicator and buzzer finished and working! Connect the remaining wires from the 7 core to the relevant wires from the lighting cluster connector in the same way. You might find that the brown wire (the right hand tail light) is unnecessary because often the tail lights on a trailer are connected to the left hand supply only. That just leaves the right hand indicator. The easiest and neatest way to connect this up is to use a spare length of green and black wire (or just a plain green wire with a black strip put on yourself down one side of the wire with a marker pen) and feed it down neatly into the jack holder well under the rearmost floor of the car. Unclip the lids on the black cable trunking in the well and hinge them open so that so you can feed your wire through it to the right hand trunking. In the right hand bundle of wires locate the green and black wire and using a crimp connector cut and connect your wire as you did before.
Once crimped together securely, close the trunking again and clip in back into its correct position. Test your lighting bar or the lights on your trailer before you refit the securing screws, the upper and lower left hand trim and the upper seatbelt bolt. And that should be job done!
Alf Beharie., April 2013
