The problem I have is that the fridge, charging and everything works fine will mains hook up but, when connected to the car the relay on the BIP constantly switches and the battery is not charged and neither is the fridge operated. The light on the fridge switched on and off constantly. The relay can be heard to switch on and off whether or not the fridge is switched on.

The power relay in the car has been replaced and the cable from the plug to the rear of the caravan has been replaced when we recently had the van serviced as the sheath had a cut in it.

No doubt a problem with the dreaded Scheiber BIP 30.65100.84 but could it simply be a faulty relay which is easy to replace?

Is JohnE still around or can anybody give me details on how to contact him?

Thank you Aaron

It could be the switched supply from the tow vehicle. You "generally" have a permanent live from the tow vehicle battery via a fuse to terminal 9 of the 13 pin socket...not that one! There is also have a live connected to pin 10 which is only live when the tow vehicle is running. This is the supply that powers your fridge and charges the leisure battery when towing.
I would check the wiring connectors in the 13 pin plug and socket first. A loose connection would create the fault that you have described. So really you are looking for a loose connector anywhere in the cabling between the towing vehicle and the BIP unit. It doesn't sound like the BIP unit itself is at fault here.

On electric hook up, none of the wiring between the towing vehicle and the BIP have anything to do with charging or Fridge power.

Edit, check the earth for the switched supply as well which should be pin 11.

Thanks for that Ray,

This is stuff I already know but the thing that was confusing us was that all the lights worked ok on tow. On the last journey home from North Norfolk back in September, my friend noticed that my lights were getting dim.

After forking out £78 or so for a towbar specialist to come out and who replaced the power relay (just in case) we plugged the caravan back in with the same symptoms. I don't think he manually checked anything before then. Must be the caravan he says.

Sitting here with a large whisky (can't drive at the moment) I thought, something that rarely happens, why did towing the van flattn the battery? I've just been out and disconnected the leisure battery. No lights at all while hooked up with engine running or not. Got the trusty multimeter out and no 12v power getting to the towbar kit.

Next stage, check the fused if I can find them but I believe a call to Towbar Express is in order.

Engineer booked for next Wednesday. Hopefully, I'll be able to point him in the right direction.

Sounds like you're on track. If the initial towbar electrics were done properly, I would expect the fuse for the permanent live to the caravan and the switched live when engine running, to be quite close to the battery in the engine compartment.

Thinking further, by disconnecting the leisure battery and there are no running lights, it looks as if the leisure battery was supplying the power to those lights, maybe some sort of backfeed through a bad earth.

Did the entire system work properly in the past or have you had some recent work done? Trying to establish if you have a system that was not wired correctly in the first place (harder to track) or a fault that has developed since like a loose earth terminal.

Certainly from your first post I suspected a loose terminal, live or earth which would make a relay clatter in and out.

You may also have some sort of "module" fitted that interfaces between your car's canbus wiring loom and the outputs to your 13 pin socket. That could cause all sorts of strange symptoms.

I've just remembered helping a chap on a campsite a few years back with no running lights on his caravan. It turned out to be a faulty module that we couldn't fix on site so I jury rigged a supply to his running sidelights just to get him home that night.

Sorry, just spotted your last post that you have a tech booked. Good luck with that, hope he or she is a good one.

Well Ray, thanks for all your time and effort. It is always good to see people willing to help us.
The engineer I've got coming next week is the company that came this morning and who fitted the towbar 6 years ago.
Everything did work perfectly until some time last year when we noticed, on arriving home, that there was not enough power in the battery for the mover.
Sincing calling the company back I endeavoured to trace the fault. There are two red wires run from the power relay back to the fuse box under the dash whese there is an in-line 20amp fuse which is good. From there a single red wire goes to the main pcb of the fuse board. On moving that wire about there is a lot of bleeping going on and looking at where is connects there is evidence of bluey/green corrosion.
Decided not to touch it as for my payment of £76.40 that can come and fix it properly.

The red wire that goes to the fuse box will be the switched live. That's the supply that powers the fridge and battery when the tow vehicle is running. It also powers the fridge relay.

Looks like you might have found the fault

However, I can't see why that would allow your leisure battery to discharge through caravan running lights.

The caravan running lights have nothing to do with the switched live or indeed the permanent live. The caravan running lights are powered through the canbus module using the car's own supply.

Hopefully your tech will have come across a similar problem before and sort it out. Good luck.