Trailer LED lights flashing
Mudding
Joined: Nov 2013
Posts: 179
Likes: 19
From: Mackenzie BC Canada
PDC and trailer
Rear PDC is de-activated when a trailer is connected because the trailer is seen as an obstacle that would set off the collision alarm. This is automatic much like other annoying things that happen automatically with all the computers that are involved. Another example is the activation of the rear wiper when the switch is off for the rear, on for the front and the vehicle is put into reverse. "Oh, the front wipers are on and you want to go backwards? I'll just turn the rear wiper on for you and smear the road grime from the highway around to scratch the heck out of your glass..." I ended up pulling the fuse. I have side mirrors that work just fine for reversing. Also I do not have PDC or a rear view camera, I call parking in reverse "parking by feel" lol
Recovery Vehicle
Joined: Sep 2013
Posts: 831
Likes: 146
From: Herndon, VA
[QUOTE=bbyer;329745]The link below is to an album I did up re the trailer electrics. The last three files in the album relate to a circuit I built to eliminate the pulsing of the trailer LEDs.
The box shown in one of the jpg's is for the round USA seven blade hookup; I also did a box up for the 4 pin flat USA connector but that is not shown as all that takes is fewer wires.
DISCO3.CO.UK Photo Gallery - NAS Trailer Socket Pin ID and Wire Colours
QUOTE]
Hey bbyer. I just posted over on Disco3 because there is a thread with somebody asking for a how-to on fabbing this sort of a box. My question is (and perhaps it will be answered over there as well), why did you use relays in your box? Aren't the load resistors all that is required? If you place one load resistor across each bulb (so... 4 total for that 7 pin socket = 1 right signal/brake light, 1 left signal/brake light, 1 tail light, 1 reverse light), wouldn't that be sufficient to fool the truck into thinking that there is a trailer hooked up and then all will be well? Can you educate me on why the relays are needed when I would think the relays in the truck should be doing the trick?
Thanks!
The box shown in one of the jpg's is for the round USA seven blade hookup; I also did a box up for the 4 pin flat USA connector but that is not shown as all that takes is fewer wires.
DISCO3.CO.UK Photo Gallery - NAS Trailer Socket Pin ID and Wire Colours
QUOTE]
Hey bbyer. I just posted over on Disco3 because there is a thread with somebody asking for a how-to on fabbing this sort of a box. My question is (and perhaps it will be answered over there as well), why did you use relays in your box? Aren't the load resistors all that is required? If you place one load resistor across each bulb (so... 4 total for that 7 pin socket = 1 right signal/brake light, 1 left signal/brake light, 1 tail light, 1 reverse light), wouldn't that be sufficient to fool the truck into thinking that there is a trailer hooked up and then all will be well? Can you educate me on why the relays are needed when I would think the relays in the truck should be doing the trick?
Thanks!
Three Wheeling
Joined: Sep 2011
Posts: 57
Likes: 2
From: SATX
CM, the relays are required to stop the pulsing of the LED trailer lights. The LR continues to probe the lines with a pulse, even when it recognizes a trailer is connected either thru the use of resistors with LED lights or when connected to a trailer with incandescent lights.
The point...the pulse will always remain at the ***-end of the LR. The relays are put into place to stop the pulse from reaching and activating the LED trailer lights.
Hope this helps.
The point...the pulse will always remain at the ***-end of the LR. The relays are put into place to stop the pulse from reaching and activating the LED trailer lights.
Hope this helps.
Recovery Vehicle
Joined: Sep 2013
Posts: 831
Likes: 146
From: Herndon, VA
Crosbo, thanks for the reply. So, I'm assuming that the LED flashing is simply a result of the LED lights using such a small amount of power? These small pulses are low enough power that they do not light up incandescent bulbs, but they will light up the LEDs? That makes a lot of sense! 
Pro Wrench
Joined: Sep 2008
Posts: 1,673
Likes: 153
From: Edmonton Alberta Canada
Thanks for the update.
I was kind of surprised re the post that the U-Haul converter worked.
As a rule, everything for Land Rover is special; how LR Engineers manage to design "different" into every system continues to amaze me.
Hence, thanks for the update and it sounds like you solved both problems. Why in a LR there always seems to be two problems at the same time; hence when you fix one, the struggle still continues.
As a rule, everything for Land Rover is special; how LR Engineers manage to design "different" into every system continues to amaze me.
Hence, thanks for the update and it sounds like you solved both problems. Why in a LR there always seems to be two problems at the same time; hence when you fix one, the struggle still continues.
Overlanding
Joined: Jun 2012
Posts: 20
Likes: 0
U-Haul adapter
FYI
I picked up U-Haul part # 39008 yesterday (CDN$29.99). Seven pin round spade to 4 or 5 flat.
To allow it to fully engage vehicle socket I had to cut off one of the little ears (that I guess are on each side to facilitate pulling it out) thus making it non-returnable.
Doesn't work.
Now need to convince a friend with an Audi that I have just the thing for the day he decides he needs to tow a trailer with LED lighting.
Be interested to hear thoughts on this:
Putco LED Light Bulb Load-Resistor Kit - Ceramic Putco Accessories and Parts P230004C
I suspect it's way too simple to work with LR though...
I picked up U-Haul part # 39008 yesterday (CDN$29.99). Seven pin round spade to 4 or 5 flat.
To allow it to fully engage vehicle socket I had to cut off one of the little ears (that I guess are on each side to facilitate pulling it out) thus making it non-returnable.
Doesn't work.
Now need to convince a friend with an Audi that I have just the thing for the day he decides he needs to tow a trailer with LED lighting.
Be interested to hear thoughts on this:
Putco LED Light Bulb Load-Resistor Kit - Ceramic Putco Accessories and Parts P230004C
I suspect it's way too simple to work with LR though...
Three Wheeling
Joined: Sep 2011
Posts: 57
Likes: 2
From: SATX
If you own the trailer you can permanently mount the resistors to the trailer's wiring harness...it literally is that simple to solve the problem of the vehicle not recognizing a trailer with LED lights. However, by design, the pulsing will continue.
To prevent the trailer lights from pulsing, you will want to install a set of relays. Doing so will prevent the vehicle-produced pulses from reaching the LED lights...simply not enough energy emitted to activate the relay.
A couple of us have built some dandy boxes as a work-around to alleviate the problem associated with trailers with LED lights and to refrain from spending the $$$'s required by one company whom I'm sure, builds a fine product.
Good luck with your project.
To prevent the trailer lights from pulsing, you will want to install a set of relays. Doing so will prevent the vehicle-produced pulses from reaching the LED lights...simply not enough energy emitted to activate the relay.
A couple of us have built some dandy boxes as a work-around to alleviate the problem associated with trailers with LED lights and to refrain from spending the $$$'s required by one company whom I'm sure, builds a fine product.
Good luck with your project.
Last edited by Crosbo; Mar 3, 2014 at 08:51 AM.
Three Wheeling
Joined: Sep 2011
Posts: 57
Likes: 2
From: SATX
Thanx Hutton.
As for the relays...nah...not that complicated. Attached is a document that I believe BByer or another great fellow provided. I added the red #'s so I wouldn't get confused and wire to the wrong post.
Good luck to you however far you want to take your project.
As for the relays...nah...not that complicated. Attached is a document that I believe BByer or another great fellow provided. I added the red #'s so I wouldn't get confused and wire to the wrong post.
Good luck to you however far you want to take your project.
Pro Wrench
Joined: Sep 2008
Posts: 1,673
Likes: 153
From: Edmonton Alberta Canada
Suggest the 50 watt 6 ohm metal surround resistors
One of the posts above asked about resistors and the link showed a 25 watt 6 ohm resistor that is not cased in metal. The link also showed an alternative just a few dollars more.
In theory, the 25 watt resistor is OK, but in my opinion, not ideal.
I prefer the metal cased finned resistors that I can attach to a piece of metal to carry away the heat generated; also those resistors tend to have twice the load rating as well so can better handle the heat. Both resistors being 6 ohm, conduct the same amps thru them, (about 2 amps @ nominal 12VDC), but the 50 watt resistor can accept the heat generated better and the cost difference is minimal.
As to why the resistor is required, the goal is to simulate a tungsten filament bulb in the trailer signal light wiring. Regarding the relay, the primary purpose is to get the LED bulb out of the circuit except when it is specifically needed for signal or brake illumination. The relay effectively isolates the vehicle computers from the LED bulb during normal straight ahead driving.
The reason we have a problem is that EU law says that a vehicle must be able to tell the driver if a signal light bulb on the vehicle quits and the notification has to be even when the bulb is not being operated. As such, the European manufacturers send a very low amperage pulse down the signal light wires whenever the engine is running.
As long as the computers can see the pulse, they know the bulbs are electrically present and OK. Secondarily, in the case of LR, it appears the monitoring system is required to tell the vehicle computer if a trailer is hooked up. This is done by noting the increased load of the trailer light bulbs and assumes the bulbs are tungsten filament bulbs. If the bulbs are LED, then the 3 has to be fooled into thinking tungsten filament bulbs are still there. If you look at the trailer light wiring diagram, page 155, you will see two FET's, Field Effect Transistors, one in the left trailer signal light wiring and the other in the left side wiring.
The pulse is weak enough that one does not see any illumination of a tungsten filament even though current is flowing thru it. With the LED bulbs however, you do see a faint illumination and that is the problem; hence the desirability of taking the LED bulb right out of the signal light circuit when just driving down the road or parked idling. Also while you can see the pulse, the 3's computers cannot see the LED's and hence cannot see that a trailer is attached.
When the LED bulb is illuminated, the pulse thing is still going on but as the LED is fully illuminated, it does not show, (as in when it is functioning as a brake light).
Land Rover of course, due to its sophistication, has more concerns than say a mere Mercedes. Yes, both have back up sensors that it would be nice to have automatically turned off, and both have four corner air suspension, however only LR had the ability to rise up and down to a significant degree. Height change, automatic or otherwise may not be desirable at speed when towing a trailer, hence the up down function has to be inhibited as well and that is really what the green trailer light on the dash is all about.
http://www.disco3.co.uk/gallery/albu...iring%2016.pdf
http://www.disco3.co.uk/gallery/albu...iring%2017.pdf
In theory, the 25 watt resistor is OK, but in my opinion, not ideal.
I prefer the metal cased finned resistors that I can attach to a piece of metal to carry away the heat generated; also those resistors tend to have twice the load rating as well so can better handle the heat. Both resistors being 6 ohm, conduct the same amps thru them, (about 2 amps @ nominal 12VDC), but the 50 watt resistor can accept the heat generated better and the cost difference is minimal.
As to why the resistor is required, the goal is to simulate a tungsten filament bulb in the trailer signal light wiring. Regarding the relay, the primary purpose is to get the LED bulb out of the circuit except when it is specifically needed for signal or brake illumination. The relay effectively isolates the vehicle computers from the LED bulb during normal straight ahead driving.
The reason we have a problem is that EU law says that a vehicle must be able to tell the driver if a signal light bulb on the vehicle quits and the notification has to be even when the bulb is not being operated. As such, the European manufacturers send a very low amperage pulse down the signal light wires whenever the engine is running.
As long as the computers can see the pulse, they know the bulbs are electrically present and OK. Secondarily, in the case of LR, it appears the monitoring system is required to tell the vehicle computer if a trailer is hooked up. This is done by noting the increased load of the trailer light bulbs and assumes the bulbs are tungsten filament bulbs. If the bulbs are LED, then the 3 has to be fooled into thinking tungsten filament bulbs are still there. If you look at the trailer light wiring diagram, page 155, you will see two FET's, Field Effect Transistors, one in the left trailer signal light wiring and the other in the left side wiring.
The pulse is weak enough that one does not see any illumination of a tungsten filament even though current is flowing thru it. With the LED bulbs however, you do see a faint illumination and that is the problem; hence the desirability of taking the LED bulb right out of the signal light circuit when just driving down the road or parked idling. Also while you can see the pulse, the 3's computers cannot see the LED's and hence cannot see that a trailer is attached.
When the LED bulb is illuminated, the pulse thing is still going on but as the LED is fully illuminated, it does not show, (as in when it is functioning as a brake light).
Land Rover of course, due to its sophistication, has more concerns than say a mere Mercedes. Yes, both have back up sensors that it would be nice to have automatically turned off, and both have four corner air suspension, however only LR had the ability to rise up and down to a significant degree. Height change, automatic or otherwise may not be desirable at speed when towing a trailer, hence the up down function has to be inhibited as well and that is really what the green trailer light on the dash is all about.
http://www.disco3.co.uk/gallery/albu...iring%2016.pdf
http://www.disco3.co.uk/gallery/albu...iring%2017.pdf