407 tow bar wiring

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moizeau
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407 tow bar wiring

Post by moizeau »

Has anyone done one of these. I think I may be trying to over complicating things, plus pictorial instructions do my head in. The kit is a Erich Jaeger 736941. I've got the separate plugs in the LHS cubby hole and it's seems too straight forward to be true. If I've got it correct I need to cut the large Black/Red connector off, splice a spade terminal on, connect that to the towing loom, connect 2 plugs, a Black/Orange that's already there to one on the towing loom, plug in the control unit, connect an earth and insert a 20A fuse into position 39.
Seems too good to be true? .

Not sure why you have to cut the the 1st plug off though, be easier to splice a male spade onto the towing loom and plug it straight in.
Cheers


Edit, unless it's not just a plug?

moizeau
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Re: 407 tow bar wiring

Post by moizeau »

Done the wiring and it seems it is as simple as I 'didn't' think. All the lights work on the trailer but.....
I've just spent the last 2 hours in Diagbox trying to tell it it's got a trailer socket.
'Parking Assistance' is a red herring. It must refer to the more complex versions, not mine with just the rear sensors that shout at you. Enable that and I get an error on the dash.
There is also 'Trailer Relay' and 'Boot harness'. Trailer relay is seen on Global Test put I can't access it and Diag says that it's there but not enabled. As far as I can see I've changed everything feasible (one thing at a time and then put it back upon failure) and can't get it to recognise that the trailer is plugged in, it just continues to shout at me when in reverse. I know that regarding the TPMs I had to make 3 (I think) changes in different menus to turn them off.
The magic box is an Erich Jaeger 736941 and seems to be amongst the best after market units on the market so I'm missing something in a particular menu or I've missed something in the wiring???
If all else fails I can either put up with the screaming on the odd occasion the trailer is on the back or put a switch in the wire from the reversing lights that feed the parking sensor box but that would be as about convenient as towing a braked trailer years ago when you had to get out and move the lever on the tow hitch.
Any advise gratefully received.

At least when I put a tow bar on the van I know that the same box will work the lights and I won't get screamed at when reversing 'cause there are no sensors.

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Paul-R
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Re: 407 tow bar wiring

Post by Paul-R »

I suspect it's very similar to my X7. I actually ran for a year or two without telling the BSI that the trailer socket was fitted. It worked fine in terms of turning the lights on and the flashers worked at the correct speed.

I wish I could be more specific about how I actually told the BSI that the trailer socket ECU was fitted. I got similar messages to you regarding the ECU being there but not recognised after a global test. I just poked around a bit and found where it had to be changed. Sorry to tantalise you but persevere - it's there!

moizeau
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Re: 407 tow bar wiring

Post by moizeau »

Cheers Paul, thanks, it's there, 2 minutes if you know which menu.......years if you don't. Just got to find the 2 minute bit