I am getting just under 12 volts at the brake pin (2) and same of the Anderson plug (fridge). However, the pins for the sway control and lights are registering only 4 volts. Does this suggest loose wires at the socket or have I missed something?
Check you dont have to charge a small supplementary 12volt battery hidden in a hatch close to your sway electrics. Just attach it to a battery charger and you should be fine
Happened to me once very annoying
Obviously you have enough voltage in your battery to start your vehicle. Your Anderson plug at the rear will either be connected with two wires directly to the battery, being the positive and negative, or directly with the positive and the negative to the vehicle body near the battery. The other alternative is the negative being connected to the vehicle body somewhere towards the rear of the vehicle.
You will need to check and clean all those connections as previously suggested.
what sway controller is installed?
I have a Dexter and it is powered from the caravan house battery.
Are you measuring the voltage with the caravan plugged in or unplugged?
Does the car have a Voltage sensing Relay in the Anderson plug circuit?
What is the make, model and year of the car?
You might get better advice from a Facebook group for your car model.
In my experiance all trailer plugs are not forever devices, as pins and sockets streach or compress, grub screws can loosen and you may see oxidixation of the wire, blackened copper wire.
My solution is to solder wires into steel rivits that fit sngggly into hole at first I insert the rivit into the the hole and mark the position of the retaining grub screw, drill a hole for the grub screw in the rivit, a bit of locktight on the grub screw thread it becomes a good strong connection.
The first option is your tow vehicle battery voltage which should be at least 12V if not more. The second is output power from the stoplight switch when the brake pedal is pressed which should be 0.00 when you are sitting still (or very low at the most). The third is output power to the brakes. If you are sitting still and using the brake pedal then that will read 0.00 but if you use the manual override it should gradually increase to 12V if you have your max output set to 12V.
