Trailer lights dim

[Robotstar5]

Don’t rule out corroded internals on the van socket. 7 pin sockets were never good at keeping out moisture.

I keep a rubber boot over my socket when it's not been used which I find keeps it clean and corrosion free.

 

[8ob]

It's handy to have a trailer plug & socket wire brush cleaning set along with an aerosol of electrical contact cleaner to ensure all the sockets & plug pins are clean .

Ensuring the trailer is correctly wired up to the plug and all light work before you even bother to plug it into your vehicle ..ensure you have some spare fuses to hand too as it's not unknown for people to miss wire both plug & socket on their vehicle & trailer as a security device , just like I did

I knocked up a box of tricks for testing trailer/tow socket wiring, its battery powered. Its so useful for checking/fault finding, you don't need anyone with you to flick switches and press pedals or a vehicle present to run through things.

.

Also got one of those two bob sand last guns for cleaning the trailer plugs/sockets

 

[Domdom]

I keep a rubber boot over my socket when it's not been used which I find keeps it clean and corrosion free.

You might, but most don’t. In fact, how many 7 pin sockets do you see with the lid broken off? And they let moisture in from the back as well.

 

[cheb]

@8ob Which abrasive did you use? I've used baking soda on motorcycle connectors with success.

 

[Maddog]

Having 12.9v on the van only means at least one of the pins is working. The earth pin is the most important one. Resistance from pin 3 to a good earth on the body is a better test.
Those lamp units earth directly back through the cable, not the trailer chassis.
Don’t rule out corroded internals on the van socket. 7 pin sockets were never good at keeping out moisture.

Thanks guys,

What would be a good resistance reading at the van pin 3 to earth?

Thanks

 

[RWD3M]

Thanks guys,

What would be a good resistance reading at the van pin 3 to earth?

Thanks

0!

 

[Smallfry]

Earthed back through the plug. Pin 3 according to the Diag off the web.
View attachment 459128

This diagram is for a 12S socket/plug . Supplementary for caravans etc, before the advent of the 13 pin setup.

Trailer socket is 12N for a trailer lighting, and the earth is on number 3 pin, NOT the centre one (which logically it should have been )

 

[Bullet2012]

Thanks guys,

What would be a good resistance reading at the van pin 3 to earth?

Thanks

0.00

Edit, beaten to it by @RWD3M

 

[CompoSimmonite]

Don’t rule out corroded internals on the van socket. 7 pin sockets were never good at keeping out moisture.

I agree. 13 pin plugs and sockets are far superior.

 

[8ob]

@8ob Which abrasive did you use? I've used baking soda on motorcycle connectors with success.

Cheap bag of pavia kiln dried sand from been and queued.

Bob

 

[arther dailey]

I knocked up a box of tricks for testing trailer/tow socket wiring, its battery powered. Its so useful for checking/fault finding, you don't need anyone with you to flick switches and press pedals or a vehicle present to run through things.

.

Also got one of those two bob sand last guns for cleaning the trailer plugs/sockets

View attachment 459225

View attachment 459226

impressed with that , cheap tool but effective ,win win.

 

[Maddog]

Ok guys, so tested the resistance on the van with Voltmeter set on 20m it’s 0.00 and on 200 it’s 00.6.

Is that ok?

That was from the earth pin on the van to one of the big M14 tow ball mounting bolts.

Thanks.

 

[Ruffian]

Would definitely check that mounting bolt then as most towbars are on anti crush tubes and not clean metal.
Would run a secondary wire to test from that earth to the striker plate of the nearest door/boot to confirm.

 

[Robotstar5]

Ok guys, so tested the resistance on the van with Voltmeter set on 20m it’s 0.00 and on 200 it’s 00.6.

Is that ok?

That was from the earth pin on the van to one of the big M14 tow ball mounting bolts.

Thanks.

Stands a chance most of that is the meter leads, touch the leads together and see what the reading is then subtract it from your 00.6 (which is already a good low number)

 

[Maddog]

Thanks guys.

I think I’ll start this weekend by removing all that insulation tape this weekend and looking at what horrors that is hiding.

Also (and I know I’m going to get shouted at for this) when I fitted the Towbar and wiring I didn’t use a specific wiring kit or smart relay I just used a universal wiring kit and tapped into the existing wires with heat shrink solder connectors (not scotch locks tho) so maybe it could get more juice from a relay. However either way it’s getting 12.9v.

 

[DAPPH]

I agree. 13 pin plugs and sockets are far superior.

Depending where the plug is made & what plastic used be aware that some plastics absorb water and make the plug a sod to connect & disconnect due to expanding because of getting wet. I had a dual socket caravan and spent about £25 on a two 7 pin to one 13 connector so I could pull the caravan on my new car /
After three weeks of holiday I had to get a new front window put in , the van stayed in the dealers yard for several months due to covid . When it came to me connecting the 13 pin up there was no way it was going to go in the socket . Old guy at the dealership said they get a lot of adaptors like this & what ever you do don't use WD 40 on the plug as it just makes things worse. Purchased a new adaptor cable and this time upon returning home it gets removed and popped on the airing cupboards top shelf till it's needed again .

 

[Red'n'Black]

Thanks guys.

I think I’ll start this weekend by removing all that insulation tape this weekend and looking at what horrors that is hiding.

Also (and I know I’m going to get shouted at for this) when I fitted the Towbar and wiring I didn’t use a specific wiring kit or smart relay I just used a universal wiring kit and tapped into the existing wires with heat shrink solder connectors (not scotch locks tho) so maybe it could get more juice from a relay. However either way it’s getting 12.9v.

Don't knock it.

I fitted a towbar to my Rover 218. A Witter I think, cost a tenner secondhand on eBay. Wiring spliced into the rear light clusters as you describe, worked fine the whole time I had it.

Towbar for my 2006 Saab had to be done by a dealer, needed an adapter module as the electrics were all Canbus, plus software updates etc, didn't see much change out of £500. And then it wouldn't drive my LED light board as it didn't draw enough current.

This is progress, so I'm told.

 

[DAPPH]

Mixing old & new technologies was always going to be problematic I put small resistors in the light units , then along came a magic resistance block to be fitted in the car. I suspect that nowadays the very latest LED fitting are sealed units with internal trigger resisters drawing current . I managed to buy a full set of LED bulbs& a full set of spares for all the lighting with internal resistors for the caravan about 12 years ago ... they cost me a small fortune .

I recall the days of trying to build computers back in 1981 , t'was a total nightmare trying to get compatible parts & when you eventually did things were superceeded a week or so later so you had to start anew again

 

[cheb]

Cheap bag of pavia kiln dried sand from been and queued.

Bob

Ta.

 

[Maddog]

From what i can see the trailer plug is new, but the yards of insulation tape on the wiring worries me. However i think a full new wiring set from plug to lights is only about £40, but with the cost of the trailer and a pair of new wheels and tyres thats putting the whole kit and kaboodle near the £500 mark. I mean i paid £370 for the trailer which isnt too bad, but it mounts up as we all know too well.