TheFoosh Posted December 13, 2016 Share Posted December 13, 2016 The lights on my trailer are playing up. Started a few weeks ago with the lights not working at all. Checked the inside of the 7-pin adapter and it was a bit corroded and lots of gunk in there so have changed that, now seats perfectly into the rear of my car. Lights worked fine. Now they are back to playing up. Sometimes the left indicator gets stuck on which keeps the indicator light on my dashboard lit up. Then when I put my foot on the brake, the headlights come on in my car! I can't figure out what to do. Any advice? Regards Nick Link to comment Share on other sites More sharing options...
jeffb5.8 Posted December 13, 2016 Share Posted December 13, 2016 Can you try the trailer on a different car to see if it's the trailer or your cars wiring issues. Link to comment Share on other sites More sharing options...
kingfishbig Posted December 13, 2016 Share Posted December 13, 2016 (edited) How old is the trailer? It is not unusual for the lights to play up when they get to the 7 - 10 year mark. What happens is that corrosion sets in. It can travel along the wires so patch ups can be a waste of time and you will probably be better off replacing the whole lot. Or you can do what I did and get a light board. This is a lot cheaper/ less hassle if you don't mind getting into the habit of removing it for launching and putting it back on again after retrieval. Edited December 13, 2016 by kingfishbig Link to comment Share on other sites More sharing options...
Swampgecko Posted December 13, 2016 Share Posted December 13, 2016 Check all the earths for your trailer wiring as well. Without seeing the harness first hand my initial reaction is you have a bad earth somewhere. the first place to look would be the trailer at the plug. White is the universal colour for the earth on trailer wiring. And depending on what plug your using will depend on where it is to go. On my trailer it is pin 3 for a 7pin flat. Now depending on how your trailer is wired up, you can either have the earth return by a wire looping to each light to supply the earth, or by the earth going to the trailer frame. If it is to the trailer frame I suggest cleaning each earth at each light, then finding where the earth for the plug is and cleaning that too. The last one to check would be the car. Make sure you have an earth to the appropriate socket on the car socket assembly. I have found, from a past life as an auto-electrician in the RAAF servicing vehicles, that the earth return there can create issues. One vehicle I looked at didn't even have an earth wire fitted on the car side, the owner was relying on the return through the towball assembly. Hope this helps, or as kingfishbig suggests, buy a new lightboard with harness, my brother just did that. BCF have either the olf fashion incandescent globe light boards or an LED version. And the come with a slection of plugs to suite. Hope all this helps Link to comment Share on other sites More sharing options...
jeffb5.8 Posted December 13, 2016 Share Posted December 13, 2016 8 hours ago, TheFoosh said: Then when I put my foot on the brake, the headlights come on in my car! I can't figure out what to do. Any advice? This makes me think it's a vehicle issue Link to comment Share on other sites More sharing options...
The Incredible Hull Posted December 13, 2016 Share Posted December 13, 2016 Do you get similar occurrences without the trailer connected? Like jeff says, I think it's your car too. Link to comment Share on other sites More sharing options...
Raymondo Posted December 13, 2016 Share Posted December 13, 2016 You better buy a new car trailer and boat, just to be on the safe side . Atleast thats what you tell the missus.? Link to comment Share on other sites More sharing options...
zmk1962 Posted December 13, 2016 Share Posted December 13, 2016 (edited) Hi Nick, Having done a fair bit of wiring (my dad was a sparkie) it sounds like you have more than one problem and are seeing the compounding effects. eg car lights coming on - sounds like something is feeding back to the car through the trailer or trailer wiring - some old trailers are wired to use the trailer as earth - a bad practice. So, as others have suggested you need to start isolating the problem - so start with your car plug and establish that it is wired correctly. Simplest may be to test your car with someone else's trailer that is known to be wired correctly or arm yourself with a 12v test light (<$5 at any auto shop or bunnings) and have someone operate the vehicle brakes and switches while you test the car plug pins. Use these diagrams .... If all is ok with the car... then work your way through the trailer wiring...again using the same wiring diagrams. Cheers Zoran Edited December 13, 2016 by zmk1962 Link to comment Share on other sites More sharing options...
fragmeister Posted December 13, 2016 Share Posted December 13, 2016 (edited) ..Only just saw the previous post - must have come through while I was posting mine. Its a very good detailed answer. As mentioned here you need to isolate whether its a trailer or car issue. Connect the trailer to another car if there is no issue then its your car - If the problem still exists then its the trailer. It looks like either the trailer plug or the car socket is wired incorrectly although bad earths can cause similar issues. If our are not comfortable with electrical wiring then you can buy a trailer wiring checker tool on the web for about $25 Bucks. Cheers Jim Edited December 13, 2016 by fragmeister Link to comment Share on other sites More sharing options...
kingfishbig Posted December 14, 2016 Share Posted December 14, 2016 I would assume the problem only occurs when the trailer is hooked up. It's not unusual for faulty trailer wiring to effect the car, though this tends to take the form of a fault code such as DSC and or ABS. It is also not unusual for trailer lights to play up with age due to exposure to saltwater. Link to comment Share on other sites More sharing options...
Greyfox Posted December 14, 2016 Share Posted December 14, 2016 Sounds like you have a crossed wire either in the 7 pin plug or due to corrision in the wiring. It is a good idea to replace the entire wiring if when you replaced the 7 pin plug the copper wires to the trailer looked greenish colour. Link to comment Share on other sites More sharing options...
Jocler Posted December 14, 2016 Share Posted December 14, 2016 Also spray your plug and socket with some WD40. Check for "hot" interconnections as well. High resistance joints due to corrosion will run hot until they eventually melt the wiring. J Link to comment Share on other sites More sharing options...
TheFoosh Posted December 14, 2016 Author Share Posted December 14, 2016 Thanks for all the responses! I did have another box trailer connected to the car, works fine. I will connect the boat trailer to the wifes car and see if it does the same. It only makes the lights in my car play up when the trailer is connected so it isn't my car however I will check. Might be time to re-wire the trailer! Link to comment Share on other sites More sharing options...
campr Posted December 16, 2016 Share Posted December 16, 2016 It goes without saying these days I guess, but replace with LEDS and you will have less trouble. There are trailer lights on eBay that come with wires attached at verious lengths i.e. 5 or 7 metres long. These give less trouble than the usual ones with a short wire attached as they eliminate joins in wire that usually end up under water risking corrosion issues. Link to comment Share on other sites More sharing options...
campr Posted December 16, 2016 Share Posted December 16, 2016 Oops, forgot to mention. You will see that connecting pins in coupling have a split in them. Try spreading pins a little with a small screwdriver, as this will give a better connection and can solve if you have a contact issue between car and trailer. Link to comment Share on other sites More sharing options...
brad_tate Posted December 21, 2016 Share Posted December 21, 2016 Regarding the previous advice, when spreading the split pins on the trailer plug a little, remember a little really means a LITTLE. 1/2-1 mm is enough, any more and you risk breaking off one side which means a new plug. Link to comment Share on other sites More sharing options...
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