Trailer Indicator Stays On When Headlights Are On

[Ryannnnnnnn]

Hello, 

My driver side indicator stays on (continually, not blinking) when my brake lights or parkers are on. A bloke at the boat ramp mentioned its probably a grounding issue. 

I'm a newb at this kind of stuff. My understanding is there should be a white cable secured to the trailer, but I can't find it? Is that with both old and newer trailers? It's probably around a 2012 model dunbier. 

I've tested it using two cars and both times I had issues. 

Any hints on how to fix it would be much appreciated! 

 

Cheers, 

 

Ryan 

[ellicat]

Check your plug first (both the plug and the receiver). Squirt some WD40 or similar in. Test. If still not working properly, open up your lights and you will probably see some corrosion. Clean it up with some hot water and a wire brush. Test. If working, pack some electrical grease around the terminals etc. If not, ask @rayke1938.

[rayke1938]

is it a flat or round plug/ If round 5 or 7pin if round usually earth problem if 7 pin earth  should be whitewire on pin 3. 

if 5 pin  still white wire on pin 3

90% of problems normally white wire undone in plug or faulty at first point at tail light.

[Ryannnnnnnn]

Thanks @ellicat and @rayke1938it's a flat plug. Doesn't have any reverse lights just the brakes and indicators. 

[AUS-BNE-FISHO]

Hey Ryannnnnnnn

Not sure if these videos will exactly address the issue you're having, but maybe they will also help. I assume rayke1938 and ellicat have it correct though!  

 

Cheers Hamish  

[Ryannnnnnnn]

Cheers yeah I opened up the connector and sprayed some innox didn't have wd40. I tried to open up the led trailer lights but there's no screw or obvious access to open it up - kind of looks sealed. Is that common? 

@rayke1938 @ellicat Couldn't see anything loose in the connector in any case. How does it ground if the white wires aren't secured to the trailer itself. 

[rayke1938]

The lights are normally encapsulated . Still white wire and terminal number 3 for earth. Can you get to where the cable from the plug joins to the wires coming out of the lights. Check the joint first for breakage or corrosion, If the cable is fairly old it may be corroded internally. Fairly common for water to ingress the earth wire and turn it black and the wire eventually goes brittle and breaks. Check for continuity between the terminal number 3 and the other end of white wire. If you want to bring boat to redland bay i can run a meter over it for you not on wednesday or sunday as they are fishing days. 0403072325

 

[Hweebe]

Ok you have tested it with two cars and have the same issue.

This means the issue is somewhere between the trailer plug and the light bulb.

Now to troubleshoot. To determine if there is a grounding issue or short you need to test for continuity. For this you will need a multimeter.

@rayke1938 is on the money. The test if you have done it before is straight forward but probably easier to explain in person

The other question i have is if your headlights are off, when you turn your turn indicator on do the trailer brake lights also flash on? (This would indicate a short between these two wires)

 

[Ryannnnnnnn]

So anywho, I ended up taking the trailer to a auto electrician who fixed the indicator going on at weird times. Unfortunately a few months later my driver side trailer Parker light(think that's what they're called, the tail light that stays on when the headlights are on) stopped working. 

I took the tail light off ad checked the cables /connections for corrosion and it looked OK. 

 

I then went to the trailer hitch plug which is a 7 pin flat connection and opened that up. From some googling, the brown cables were for the tail lights, so I loosened the screw to check for corrosion on the cables which also appeared fine. I put the cables back in underneath the screw and tightened it down. 

After resitting those brown cables both tail lights aren't working. Aaaarrgh! I wasn't very popular with the Mrs when I told her I made it worse. 

Any ideas? The leds come on when braking, just not when my headlights are on 

[Old Scaley]

If you are confident that you have the wires in the right holes try putting a thin flathead screwdriver in the split in the pin and separate the two sides slightly. Over time the gap closes a bit and doesn’t give a good connection into the plug at the car end. Hope this makes sense. 

[Ryannnnnnnn]

That does make sense at the time I checked that the pins weren't too closed, but I might try and widen them anyway to ensure good contact. 

 

Only thing I thought was if there would be any fuses specifically for that trailer light circuit somewhere that I buggered but I didn't think there would be. Not very cluey with this sort of stuff 

[Old Scaley]

No fuses at the trailer end. Do the car’s parking lights come on? If so it has to be in the trailer wiring somewhere, most likely in the plug. Could be the plug at the car end but more likely the one you have been working on. If the car parking lights are not working then you should be looking at the fuse box. That would be unlikely since you had one working before and I doubt each side would have its own fuse.  Trailer lights sure can be frustrating. 

[Ryannnnnnnn]

Yeah sure can thanks @ellicat will take a look at that

[Jimmyjack]

I've had issues and just bought a flat plug ofr mounting on the car from superchop which has little LED's at the connection. When the wire is active the LED comes on. So if for example the left blinker LED light flashes when you put the blinker but there's no blinking at the trailer light then there's an issue between the plug and the light, or at the light itself. If the blinker is on and the LED isn't flashing at the 7 pin connection, then the problem is from the car, and is not the trailer. Just helps a little with isolating any issues and wasn't any more expensive than other mounts.

[Ed.]

That would be a helpful plug to have, I am that most of us who have trailers would have had some sort of issues with their trailer lights at some stage.