Break-away switch

It should be connected to the battery in the van. And so should the earth.

Have you connected the two wires from the switch into the brake circuit

A breakaway is not normally connected to the 7 pin plug at all.

It is supposed to have a battery that keeps the brakes on for at least 15mins.

When you pull the pin the brakes and brake lights should come on for the required time or until you put the pin back in.

Also never connect the wire to the towbar It should be connected to a point that if the towbar should fall off (they have) it will activate and pull the van up. Read the instructions carefully.

Is there a unit or just the switch as most have a unit with a battery incorporated in the circuit EG Breaksafe 5000.

Not quite clear Whitey, but it sounds like your Breakaway system battery would be kept charged from the car when running, hence the mention of the 7 pin plug. If you are connecting to the in caravan batteries instead, you should remove the small breakaway battery and connect it direct to your solar charged in house batteries. Does this make sense to the gurus?

Motherhen

Thanks Graham H and Mother Hen. I am getting 12 volts from the battery box to the breakaway switch before I pull the pin. I would have thought that once I pull the pin the 12 volts would have made a full circuit to the brakes, thus activating the brakes. Instead, the voltage drops to about 3.5 volts.
I have a battery unit as well as a switch and the battery unit is connected directly to my in-caravan batteries. And yes the wires from the battery are connected to the brake lines.
The unit I have is "The Engager" Model 20099 breakaway system.
I have taken on board all your comments and and thank you both for them.

Regards
Whitey

The wiring diagram on my Breaksafe is as follows

Orange x2 to Breakaway switch

Blue to brake + line from 7 pin plug pin 5 normally Blue

White to earth on chassiis or to white wire on 7 pin plug Pin 3

Red to stop light circuit normally red from 7 pin plug

Black 12 volt from 7 pin plug pin 2

As the battery is only used if van disconnects Charging it from the car is sufficient.

I dont know about yours but mine has a built in charger and uses the 12 volt to charge through that.

Sounds like you have a short or a bad earth

Otherwise the battery is not fully charged What test light comes on green or something else.

What happened Everyone asks for advice Very few say how they fixed it