Voltage drop to the caravan rear lights

[nelson8217]

Hi, I've found the rear lights are dim on the caravan and the voltage is only 7.5v. At the car 7 pin socket it is 11.5v engine off (12.5v running) but at the 7 pin plug the voltage has dropped by about 3v which I can't believe is correct. I have replaced both parts of the 7 pin plug and socket but it hasn't made any difference. Does anyone have any thoughts, ideas or suggestions for the voltage drop?
Thanks
Peter 🙁

 

[colin-yorkshire]

poor earth/return point thus causing resistance in circuit. check all other circuits supplied by plug.

 

[bertieboy1]

The cause of voltdrop in dc circuits is resistance,there must be some increased resistance in you rear lighting circuit.If the wiring hasn't changed then look for corroded or bad contacts,clean up the light bulb contacts and the lamp holder contacts .Check all connections (including earth/return) are sound and have no corrosion.

 

[TonyH1]

How are the connections made to the vehicle wiring? Sometimes they're "piggy backed" using plastic connectors such as scotch-locks. It might be worth checking these if that's the case.

 

[GStockton]

From what you say I agree with Tony H I think you will find the wiring to the 7 pin socket is connected to the car with Scotch loks These devices are( the work of the Devil) and will cause you all sorts of poor connections High resistances etc

 

[rosies]

Personally I would connect a 12v battery with inline fuse directly to the caravan 7 pin plug ( 12n , black plug ) . Get yourself a online 7 pin plug / socket wiring diagram ( free ) relevant for your year of caravan ie , pre 1999 or post 1999 . Connect the negative battery wire to the relevant caravan 12n plug pin ( pin 3 white , earth pin ) .
Then connect the fused positive wire to say pin 7 ( side light ) then pin 5 ( side light 2 ) then pin 6 ( brake lights ) .
ALL these should give nearly 100% of the battery output measures approx. 12.4 volts at the bulb . This check would show wether the problem lies within the caravan or car/towing vehicle . If low/a lot lower voltage is showing on the caravan test then the fault is within the caravan circuitry , and is almost certainly one of the above posters answers to rectify .Steve .