Problem with lights on Trailers

[Nightrod111 Member Find all posts View Profile Close Nightrod111]

Hi Guys,

I have a Hayman Reese Towbar fitted to my 150 Prado.
Today i hooked up a trailer and noticed my Hazard lights would breifly flash once then not turn on at all. My brake lights also wouldnt work on the trailer.
I hooked up a second trailer and noticed that when i turned the hazard lights on the brake light would flash as well.
I tried a 3rd trailer and everything worked except the brake lights.

I used a test light to check everything and it all seems fine. hazards work, brakes and lights all light up the test light. I also used the same earth point as the trailer plug uses thinking it may be a fault in the earth..

Any suggestions?

[winniliss Avid PP Poster! Find all posts View Profile Close winniliss]

Sometimes electrical faults don't present themselves unless the circuit has a load on it that represents say 50% of what the circuit can handle. It might pay to open up the plug on the vehicle to make sure there is no corrosion, stray strands of wire or loose wires that may be shorting out. Then do the same on your trailer plug. From there start checking the wire loom for damage (most likely the trailer unless you have done some recent wiring on your vehicle).

Winston.

[Nightrod111 Member Find all posts View Profile Close Nightrod111]

tried all that. Ive spent most of my day checking my wiring and driving to friends houses and plugging their trailers into my car :X

[winniliss Avid PP Poster! Find all posts View Profile Close winniliss]

With your trailer plug just wire up the earth and brakes. If that works then disconnect your brakes and try parkers and so on testing each circuit on it's own. Once you have done that and there is no issues connect your brakes and parkers and see if they work together and so on. Does your trailer have LED or normal incandescent globes? If it's the latter take the light cover off and checking inside.

Does your trailer earth run to each light on the trailer or are you using the chassis on the trailer for earth and earthing each light to the trailer chassis?

[Nightrod111 Member Find all posts View Profile Close Nightrod111]

I didnt try this as i hooked up 3 different trailers to my car. One of the trailers has L.E.D lights. I even tried hooking a trailer up to my mates car and everything worked as it should

Would the gauge or thickness of wire have anything to do with it? Being after market they wire tapped into the standard harness which has very thin wire and joined that to thicker wire.

[D4D Addicted PP Member Find all posts View Profile Close D4D]

Being after market they wire tapped into the standard harness which has very thin wire and joined that to thicker wire.

That doesn't sound right, the Prado has a trailer loom complete with extra relays etc.

[Nightrod111 Member Find all posts View Profile Close Nightrod111]

Yes the trailer loom has a connector on it, however they wire tapped into that rather than using a genuine connector plug..

[D4D Addicted PP Member Find all posts View Profile Close D4D]

I'd ask the fitter if they used the proper loom, if not get them to show you it working.

[Nightrod111 Member Find all posts View Profile Close Nightrod111]

I might have to go see the fitter because im out of ideas.. The wiring loom that he wire tapped into to my factory harness is substantially thicker. Perhaps the thicker wire that he used is drawing too much current??

[Nightrod111 Member Find all posts View Profile Close Nightrod111]

i dont think it has the extra relays etc. I was was under the assumption that the car came standard with the relays but this doesnt seem to be the case..

Is this the correct harness? http://www.ebay.com.au/itm/Toyota-Pr...item20d4cec217

[winniliss Avid PP Poster! Find all posts View Profile Close winniliss]

I might have to go see the fitter because im out of ideas.. The wiring loom that he wire tapped into to my factory harness is substantially thicker. Perhaps the thicker wire that he used is drawing too much current??

Thicker wire wouldn't be an issue. My loom that I attached was a Toyota loom that had relays etc as D4D said. Maybe this is the issue seeing your trailer works on your friends. I know it has a relay for the indicator etc... Speak to the installers to what they exactly did.

This is an example loom for a 150. http://www.ebay.com.au/itm/Toyota-Pr...-/141009273367 and is a must for the vehicle to run correctly.

Winston.

[Nightrod111 Member Find all posts View Profile Close Nightrod111]

I will call the installer tomorrow and see what he did. Im pretty sure i dont have any additional relays etc.

cheers

[D4D Addicted PP Member Find all posts View Profile Close D4D]

Most don't fit the Toyota loom as it adds about $200 to the install.

[mjrandom Out of control poster! Find all posts View Profile Close mjrandom]

I seem to remember that the Toyota install uses a relay box to give more juice to the lights. I know on my 90 which I fitted I just tapped into the existing wiring and the hazards would flash once then stop and nothing would work until the hazards were switched off. Too much load on the system. Somehow. So since then I just get the Toyota bits. If you can hook up a trailer with LED lights see if it works ok, the lower load might indicate a similar problem. I assume the earth is hardwired and not relying on the towball? You will know if you have the relay box, when the indicators or hazards are on it ticks loudly from the jack compartment.

[Nightrod111 Member Find all posts View Profile Close Nightrod111]

The earth is hardwired.
Im pretty sure its missing the relay box.. I will call the stealership and see if they will supply the fitter with a genuine harness as the car is only 3 months old!!
I dont tow very often but when i do i need my lights to work!!!

Thank you guys for your help, i will keep you all posted..