Rear Fog Light help

[lilevo]

Hello, USA based here. I'm installing the factory rear fog lights on my US spec LS460.  I have the correct wiper stalk installed and the rear fog lights, however the switch doesn't activate the lights. 

Everything related to the boot fuse box/bcm, canbus lines, wiring to the rear fog lights are the same for all LS460 models worldwide.  I think I'm missing something related to these open plugs.  Was hoping a member could take a snap shot of these connectors in the boot to see if they are plugged into something, or a jumper harness on a UK spec LS460 that I need to do in order to link the switch to the rear fuse box to the fog lights.  

 

 

 

 

[scudney]

Silly question but do you have your headlights on when you try and activate or switch on your fog lights,just a thought 🤔 

[steve2006]

Very good point John, the rear fogs generally only come on with dipped beam headlights on also.

[lilevo]

Yes, I spent about 8 hours trying to reverse engineer the wiring and looms as I have no access to non-US wiring diagrams or any other car to compare to.  The front fogs work and everything else works properly.  There is simply no 12v at the rear fogs at any time.

Either the rear fuse box is not getting a canbus signal to turn on the rear fogs, or the rear fuse box is not letting that signal get through to turn on the rear fogs.  Without knowing where that loose white plug goes or access to any wiring diagrams I'm at a stand still.  The rear fog 12v wire ohms out at that open white connector, which is why I think that connector is simply left open in countries where rear fog is not standard, and connected or jumped to itself in order to enable it.

 

[ambermarine]

5 hours ago, lilevo said:

Yes, I spent about 8 hours trying to reverse engineer the wiring and looms as I have no access to non-US wiring diagrams or any other car to compare to.  The front fogs work and everything else works properly.  There is simply no 12v at the rear fogs at any time.

Either the rear fuse box is not getting a canbus signal to turn on the rear fogs, or the rear fuse box is not letting that signal get through to turn on the rear fogs.  Without knowing where that loose white plug goes or access to any wiring diagrams I'm at a stand still.  The rear fog 12v wire ohms out at that open white connector, which is why I think that connector is simply left open in countries where rear fog is not standard, and connected or jumped to itself in order to enable it.

 

Hi Jason

The best way to resolve this is trial and error take the live pin on the white connector through a jumper to the fog light positive it should already have a ground,  if not ground it to the frame then using a circuit test try each plug until the bulb reacts if there is no response to this exercise it may require a relay in line after the white plug. Years ago  on my Mark 1  I took out the  failed antenna and replaced it with a aftermarket unit and clipped to the frame of the antenna was a relay which we assumed was for the antenna later we discovered the rear fog lights did not work . I was fortunate to have the workshop manuals including the wiring diagrams and on checking it the relay we assumed was for the antenna was for the rear fog lights. Now I know the US spec as rear screen antenna but it will still be wired for a relay on the rear fog lights which as to be fitted for them to work.The wiring for the relay should be done via a live fused circuit and the trigger for the relay will come from the white connector .

[ambermarine]

Further to my last post I have dug out some of my switches bulbs and relays from My scrapped Mark 1 and I think the relay depicted in the shots is the standard switch relay used by Lexus on the LS It is used for most of the instrument and light switches and I am fairly sure it is used on the fog light relay. All the information to retrieve a wiring harness from a breaker is on the relay.

[ambermarine]

Although The relay information is for the LS400 the principle is the same and you need to find the relay that fits that socket from Lexus it will have a code like the one in the pics but may be of a different shape, check out the other switch relays on your car and look for similar male socket pins. There should be no need for any wiring it is already there you just need the relay so if you can find a relay on the car that fits that white socket try it and if it works you have your relay code and you can order one up .Or just ask your Local Lexus dealer for a rear fog light relay,the cut in the frame above the socket is were the relay clips on for support.

[lilevo]

Everything is already there.  The fuse for rear fogs is in the boot fuse box, as is the relay, and all electronics. I really just need a picture of that white connector.   I did a conversion on an IS-F without issue, for some reason this one is more complicated. 

[ambermarine]

16 hours ago, lilevo said:

Everything is already there.  The fuse for rear fogs is in the boot fuse box, as is the relay, and all electronics. I really just need a picture of that white connector.   I did a conversion on an IS-F without issue, for some reason this one is more complicated. 

I am not convinced everything is there if that were the case there would not be a plug with no outlet and we would not be having this discussion.Having studied the fuse box module in the left of your picture posted with the query the bottom as four male inserts for harness connections check if one of these is not being used and is vacant if that is the case there will be a requirement for a specific cable that connects that module to the spare plug in the trunk.

According to my information when you do find this cable and it is connected successfully the circuit as to be programmed with Lexus workshop equipment for the lights to work. 

[lilevo]

The connector doesn't reach the fuse box and there are no open ports. It either connects to itself with a jumper connector, thus connecting wires inside the connector, some type of jumper harness, Y-splitter, or?  

I have all the Lexus workshop equipment and there is no external programming to enable the rear fog lights

[ambermarine]

2 hours ago, lilevo said:

The connector doesn't reach the fuse box and there are no open ports. It either connects to itself with a jumper connector, thus connecting wires inside the connector, some type of jumper harness, Y-splitter, or?  

I have all the Lexus workshop equipment and there is no external programming to enable the rear fog lights

I suggest you do some research on the internet as I have done on your behalf I have found various examples of the fuse box from the trunk for sale on eBay they show the sockets in the base of the case after the loom connections have been removed .It may be helpful to find weather your box as all its loom connections in place if not then that may be the answer to your problem. But for now I think I have spent more time on this inquiry than I have on any other so I will leave you to it.

[lilevo]

As mentioned before, the fuse box is the same no matter where the LS460 was sold around the world.  All I am looking for is someone with a 2007+ LS460 to post a picture of that connector.

[lilevo]

Upon further inspection, the "caps" on those plugs aren't just caps.  They DO in fact jump wires to each other on those male connectors. The other ends of these two cables terminate the same way with caps at the main body ecu / fuse box.

This leads me to believe that it's possible these caps are different for different regions that have different tail lights or other features, with jumps in different locations.

[lilevo]

If that's not it, then I may need to find a main body ecu (front driver fuse box) from a left hand drive europe car.