LED Lights won't work

L

lough

Well-Known Member
I have LED lights on a trailer and they won't work when I plug them into the tractor which is a 2008New Holland TL90A.
The lights are working on the trailer as I plugged them into the car. The seven pin plug on the tractor is working as it works a lighting board with the old style lights.

What is wrong when the tractor won't work the LED lights on the trailer
 
lough said:
I have LED lights on a trailer and they won't work when I plug them into the tractor which is a 2008New Holland TL90A.
The lights are working on the trailer as I plugged them into the car. The seven pin plug on the tractor is working as it works a lighting board with the old style lights.

What is wrong when the tractor won't work the LED lights on the trailer
Click to expand...
Earth or ground in wrong maybe?. I think tractor plugs are wired a bit different to cars as in there's a left and a right side for the tail lights whereas a car typically takes the power for the tail lights on the trailer from the left or right only. In other words a tractor will have 2 live pins when the lights are on while a car will only have one live pin in the socket. I could be way off here though.
 
i,ve heard of this before only the opposite as in they would work on the tractor but not the car, couldn,t find the cause of it but took off the leds and put on rubbolites and worked perfect on the car :scratchhead:
 
Led's afaik only work with the current going one direction as in one side is positive, the other negative.
 
diesel power said:
Earth or ground in wrong maybe?. I think tractor plugs are wired a bit different to cars as in there's a left and a right side for the tail lights whereas a car typically takes the power for the tail lights on the trailer from the left or right only. In other words a tractor will have 2 live pins when the lights are on while a car will only have one live pin in the socket. I could be way off here though.
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7 pin plugs on tractors and car are wired the same, brown (into no. 5 pin) is the RH tail light and black (into no. 7 pin) is the LH one. Some lads, through laziness I think, wire both tail light wires into one pin but this puts an extra load on the fuse for that side as each side would be fused separately in the majority of cases.

lough said:
I have LED lights on a trailer and they won't work when I plug them into the tractor which is a 2008New Holland TL90A.
The lights are working on the trailer as I plugged them into the car. The seven pin plug on the tractor is working as it works a lighting board with the old style lights.

What is wrong when the tractor won't work the LED lights on the trailer
Click to expand...

I would think you will need to check your plug and socket. I've never came across a situation like that, I've often tried lights out to see if they work on the car, the 885 or a modern tractor and all do work equally well.
 
I wonder is the tractor trying to sense the presence of a device attached in the plug before it will drive it. It may be the leds need a resistor in parrallel to get it to 'sense' the lights connected. Not sure which circuit though to stick resistor in most likely indicators.
 
My first port of call would be to fit a new plug on the trailer, making sure its as the diagram below. It will cost pittance and at least it will rule that much out.
If that fails, replace the tractor socket


trailer-plug-wiring-diagram.jpg
 
Check the plug on the tractor in case the pins have closed in and are not making contact, a small philips screwdriver will spread them again, there are cheap plug in plug/socket testers which you can buy to test both as well.

like this picture
tester.jpg
 
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You need a resistor on the line led lights require so little voltage to run them or if you take an earth off the rear lights earth them direct to the body
Just to be sure test with a multi meter on the trailer lights see what sort of voltage your getting
 
Heisenberg said:
You need a resistor on the line led lights require so little voltage to run them or if you take an earth off the rear lights earth them direct to the body
Just to be sure test with a multi meter on the trailer lights see what sort of voltage your getting
Click to expand...
You would only need a resistor on the indicator line though, and then only to ensure the tell tale on the dash works
If the OP has zero lights working, a bad earth connection must be highly likely
 
Mike said:
You would only need a resistor on the indicator line though, and then only to ensure the tell tale on the dash works
If the OP has zero lights working, a bad earth connection must be highly likely
Click to expand...
Yes that’s through perhaps the other trailer is earthed through the body in some way again with the multi meter do a continuity test on the earth wire in the tractor 7 pin socket
 
kkk2 said:
Check the plug on the tractor in case the pins have closed in and are not making contact, a small philips screwdriver will spread them again, there are cheap plug in plug/socket testers which you can buy to test both as well.

like this picture
tester.jpg
Click to expand...

I bought one of those things thinking it was going to save me hassle, it caused me a lot of head scratching for a while as it showed a fault on one of the indicators, the tester itself is faulty.
A multi-meter is a better bet or a cheap fix is use a bulb holder with a correct voltage bulb in and two wires attached to check if you have power at a particular point.
 
It has to be an earth problem, LED is a light emitting diode, a diode will only allow current pass in one direction so the earth problem is most likely in the tractor side as the lights are OK with the car.
 
There's plenty of led side marker lights on the market that will work with live or earth going to either wire.
Arthur said:
It has to be an earth problem, LED is a light emitting diode, a diode will only allow current pass in one direction so the earth problem is most likely in the tractor side as the lights are OK with the car.
Click to expand...
 
I tried the lights again today with the tractor, I had the tail lights switched of and I put on the indicator on the left side, it barely lit three of the seven/eight bulbs in the LED, there is two side lights on the left side of the trailer and two on the right side of the trailer, when I had the left indicator on the side lights on both sides were flashing, when I put on the right indicator the same thing happened.
The tail lights won't work and when I have them switched on the indicators don't work

When I tried the lights on the car everything worked as normal, the side lights came on when I put on the tail lights and they didn't flash when I put on the indicators. When I was checking the lights I got out to look at them and wasn't looking at anything on the dash
 
lough said:
I tried the lights again today with the tractor, I had the tail lights switched of and I put on the indicator on the left side, it barely lit three of the seven/eight bulbs in the LED, there is two side lights on the left side of the trailer and two on the right side of the trailer, when I had the left indicator on the side lights on both sides were flashing, when I put on the right indicator the same thing happened.
The tail lights won't work and when I have them switched on the indicators don't work

When I tried the lights on the car everything worked as normal, the side lights came on when I put on the tail lights and they didn't flash when I put on the indicators. When I was checking the lights I got out to look at them and wasn't looking at anything on the dash
Click to expand...

A simple way to check you earth is to sandwich a piece of cable into number 3 pin of your plug while plugging in the 7pin,you then earth the other end onto something like you pick up hitch hook (usually shiny).

Sometimes you'll have a bad earth to the plug and wouldn't know till you unhitch as it earths through your hitch.
 
lough said:
I tried the lights again today with the tractor, I had the tail lights switched of and I put on the indicator on the left side, it barely lit three of the seven/eight bulbs in the LED, there is two side lights on the left side of the trailer and two on the right side of the trailer, when I had the left indicator on the side lights on both sides were flashing, when I put on the right indicator the same thing happened.
The tail lights won't work and when I have them switched on the indicators don't work

When I tried the lights on the car everything worked as normal, the side lights came on when I put on the tail lights and they didn't flash when I put on the indicators. When I was checking the lights I got out to look at them and wasn't looking at anything on the dash
Click to expand...

The lights worked grand when on the car but the car wasn't attached to the trailer, if the tractor isn't attached to the trailer the lights don't work at all. When the trailer is attached to the tractor the indicators just about work.
 
lough said:
The lights worked grand when on the car but the car wasn't attached to the trailer, if the tractor isn't attached to the trailer the lights don't work at all. When the trailer is attached to the tractor the indicators just about work.
Click to expand...
Earth problem, between the tractor socket and tractor.
 
Terminals tractor side was my thought too.

Have a big problem with father wigglinh plugs up and down like a madman to get them off here. Often closes the pins up.
Quick shove of a pocket knife into the cross works well!
 
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