External Side Lights are Dim

Symptoms:- With the caravan connected to the car with the 12N plug. With the side lights off, the indicators and brake lights were okay. Switching on the side lights, the lights are dim.

Upon searching for information on the internet it seems this problem is caused by a bad earth connection.

First thing to do was to get a good picture/diagram of the wiring for the 12N plug,with this in hand and a multimeter it was time to look for the cause.

The lighting on the caravan consists of two side lights on the front and a high level light on each side.	Two rear light clusters and two number plate lights.	The brake lights were okay, so at the 12N plug continuity was checked between pin 6 (red) and pin 3 (earth), low resistance-good. Then the other pins and earth, they were high-no good.
Next I wanted to verify the cables were okay, so the first thing to do was to remove the bulbs, starting with the front side lights.	Then the high level side lights on each side of the caravan.	Followed by the two number plate lights.
The two rear light clusters were next.	It was then a matter of shorting each pin in turn with the earth wire. (In this case pin4/green wire which is the right indicator)	On the rear right light cluster the multimeter can be connected between the white and green wires. No resistance tells me the wires are good. This was performed on the white/earth cable and all the other wires in turn. Same result, so all the cabling is good.
Attention was now drawn to the light clusters, this whole strip is earthed. Now to remove any corrosion on the blades and bulb holders, using mostly wet and dry paper.	The bulbs were given a rub to get to shiny metal.	Scraping a connector with a sharp blade.
Bulb central connections sanded.	And the part where the bulb outer body touches.	The spade connectors where gently sqeezed so that the connection when made would be a tight fit.
After connecting everything back up (electrically), plugging in the 12N plug and trying all the lights. All worked with the exception of the left number plate bulb. This was fixed by bending the supply pin to the bulb a little, to make sure of a good connection.	After cleaning the body and light unit it was time to put everything back together.	Four screws hold the rear light clusters.
Once all put back together the lights were then checked again, they were all brighter to my eyes.	And here are the side lights, all good again.

So it is important for good electrical connections for the lights, over time corrosion of the main earth strip in the rear light clusters must have caused a bad connection to develop, sanding with wet and dry to get good metal to metal contact cured it.

 Page Created 12th November 2011/ Updated 6th December 2011