Car Trailor Electrics

[jeremy 71]

Basically i'm a little confused. There is a current at the bulb holder end although seems a little low around 10.6v connected across the positive and earth terminal within the trailor board brake light, but put a bulb in and it drops to zero when applying the brake pedal. I have tried the board on another car adn it works fine. I have also checked all the electrics at the tow point on the car and all is fine with the connections. So what would likely cause the voltage to drop when trying to be fed through a bulb as opposed to through a volt meter? Thanks Jeremy

[pugdamo 111 2 Cars]

All your checking with a voltmeter is voltage,its amps that will light the bulb,you can get good voltage through a badly corroded/poor connection but there will not be enough current to light the bulb,when your putting the consumer in the circuit e.g the bulb its dropping to zero because its probably got a poor connection somewhere within the trailer board.I would have thought all the lights would use the same earth so if its only the brake light that isn't working i will probably be the supply to that that has the fault.

Get a bulb with a couple bits of wire attached to it and go from the earth pin in the bulb holder to a supply from a different light,if it works you know its a supply fault,then its either find the poor connection or run a new piece of wire through the board.

Hope that helps.

[pugdamo 111 2 Cars]

Just realised you said you tried your trailer board on another car not tried another trailer board on your car,basically the same applies just you will be doing the tests at the socket on your car

[jeremy 71]

Thankyou what you say makes perfect sense. Will check the connection behind the rear light tomorrow.

[glenwah 20]

It's more than likely the connection on the back of the socket that's corroded, not where it connects into the loom, the sockets are open to the elements and go green very quickly if not protected properly.

[jeremy 71]

It's more than likely the connection on the back of the socket that's corroded, not where it connects into the loom, the sockets are open to the elements and go green very quickly if not protected properly.

Normally I would agree, however I have already looked at all the connections, stripped some more insulation off and re-connected all terminals.

[TooMany2cvs 65]

It's more than likely the connection on the back of the socket that's corroded, not where it connects into the loom, the sockets are open to the elements and go green very quickly if not protected properly.

Agreed. For the cost of a length of 7-core cable and a plastic socket, it's barely worth fannying about. Don't waste the extra on an ally socket - I've always found 'em going furry and seizing closed in a short time, unless you lubricate 'em regularly.

 

Odds-on there's a wodge of bodgeloks attaching it at the light clusters, too.

Edited April 3, 2013 by TooMany2cvs

[chris-gti 14]

Is this on all the lights on the board or just one? if all then it's likely just the car earth isn't good enough. pop a wire from clean metal on the car to Pin 3 on the socket (should be white wire)

 

 

if that cures it then your issue is the earth to the towing vehicle. I would just run a good gauge wire with ring connector to a bolt in the chassis or body.

 

Worth squirting some electrical contact cleaner in the socket and working the plug in and out a few times, cleans up the contacts.

Edited April 3, 2013 by chris-gti

[jeremy 71]

The fault is only with the brake light, and yes there are a load of those scotch blocks behind the passengers rear light so this is what I will be checking next.