Old one I bet but help !!!

[Tattooedjock]

Firstly hello to all members
So got my first old school Volvo 740gl on a G plate recently which I love
Was purchased to carry around 2 kids 2 Great Danes and the usual stuff
So it’s an estate which is perfect for the above
Now my problem
The boss basically wanted a caravan so I managed to find out 940 towbar fit as was struggling to find a 740 one. I purchased one for £20 which I thought sweet
Am now finding it hard to find any information on how to wire the electrics in
I looked for the 10 pin adapter but am guessing it’s only in 940s
Am unsure if relay needed as will only be running a 12n plug
Am not too bothered about bulb warning light staying on
Have read scotch locks are rubbish
Basically I have Saturday to try and wire it in myself as she went and bought a caravan I am due to collect Sunday lol
My plan so far was to cut in to wiring and fit spade connectors to relevant 7 wires
Any help info wisdom guidance much appreciated
Cheers
Dave
O or if you know a cheap auto electrician in the Colchester area who wants a bit of work please send contact details

[Laird Scooby]

All the 740s i've had with towbars have had the wiring run from the fusebox to the rear lights. That's because the wiring for the lights goes through the bulb failure unit.

The problem isn't so much that the Bulb Failure Warning light stays on, more that it can burn out the BF unit. If that happens you end up with no rear lights at all.

Apart from having to route the extra length of cable in, it's probably easier to run the 7-core from your 12N socket, through the valance, into the left hand cubby hole between the wheelarch and tailgate, under the carpet round the wheel well then along the inside of the sill to the front, behind the passenger footwell carpet and into the back of the fuse box where you should be able to pick up all the lighting feeds to the BFU fairly easily.

[Tattooedjock]

I guess this would be bad but could I do a quick temp fix then take it to a proper auto electrician
There’s one that does towbar and electrics not far from me but they can’t do it before weekend and I need it done by Sunday

[Laird Scooby]

Originally Posted by Tattooedjock

I guess this would be bad but could I do a quick temp fix then take it to a proper auto electrician
There’s one that does towbar and electrics not far from me but they can’t do it before weekend and I need it done by Sunday

If you're going to do that, use Scotchloks in the fusebox to connect into the feeds to the BFU - that way when the auto-electrician comes to do it, most of the hard work is done, he just has to cut the wires and join them by soldering with heatshrink to protect the joint after.

Scotchloks aren't a good long term solution (i'm being polite here!) but will hold for a year or so, especially in a relatively protected environment such as behind the fusebox.

[Tattooedjock]

Thanks mate
Am guessing the whole fuse box pulls out threw the ashtray?

[Laird Scooby]

Originally Posted by Tattooedjock

Thanks mate
Am guessing the whole fuse box pulls out threw the ashtray?

Spot on! Can't quite remember the procedure but once the ashtray is out, there's a little flap that has "LIFT" written on it, then there are a couple of clips, one each side push them outwards and slide the fusebox out. Probably best to disconnect the battery earth before pulling it out, just to be safe. Once out, you can make sure nothing is likely to short to erth and reconnect the battery earth (make sure the keys are out of the car when connecting/disconnecting the battery earth) so you can test the feeds and splice in as needed.

[Ian21401]

If you do a search on “Towing Electrics” in this section you should find two useful threads. “Tow Bar Wire Socket” and “Tow Bar Electrics Question” where it is explained how to fit a 7way bypass relay ( for 12N ) and a Smart relay ( for 12S).
GPL1968 did all the hard work but I followed his instructions. Everything worked from the start and has not caused any problems.

[gpl1968]

If you use a bypass relay to connect the towing socket you should be able to tap into the loom that runs around the left hand side of the boot. You would need to remove the trim panel under the window to gain access.
You would then need a permanent live feed to power the relay and if you have a powered aerial you could tap into it's permanent live feed (15A fed from fuse 5 I believe).
This would stop you having to pull the interior apart to route cables to the fuse board.
I used a relay like this: https://www.towsure.com/smart-7-way-...hoCdZwQAvD_BwE
It also provides the legally required indicator buzzer (and optional output for a dashboard telltale) that operates when trailer lights are connected.

[jonnyf90]

Originally Posted by gpl1968

You would then need a permanent live feed to power the relay and if you have a powered aerial you could tap into it's permanent live feed (15A fed from fuse 5 I believe).

Forgive me if I'm wrong, but pretty sure the power aerial is a switched 12v - at least it was on my 940 'loon!

Cheers

[Laird Scooby]

Originally Posted by jonnyf90

Forgive me if I'm wrong, but pretty sure the power aerial is a switched 12v - at least it was on my 940 'loon!

Cheers

It still needs a permanent feed to retract when the igniton is switched off and the radio with it. Unless it's a manually switched (semi-automatic) electric aerial in which case it will have a dashboard switch.

Proper ones are fully automatic and the aerial extends and retracts automatically when the radio is switched on/off or if the ignition is switched off while the radio is on.