Rear lights fault

[Chinesetuba]

I've recently noticed that the rear lights on my '97 LS400 aren't lit as they should be. Even though the top and bottom bulbs in the housing are twin filament, only the sidelight works at the top and only the brake lights work at the bottom. I've changed the bulbs for brand new btw. but made no difference. Any help appreciated, thanks 

[Malc1]

They made no mention at the last service and MOT ?

does the reversing light work ok ? 

They might actually be ok, they work ! 
rarely look at my car from the rear tho’   Others here might have a view for you 🤔

Malc 

[Chinesetuba]

Perhaps they didn't know what's supposed to light up, as long as there's something at each side that works, maybe. I don't go to Lexus for MOT and I do my own oil changes etc.

[Razor61]

For my 98 LS400 I figured out that although dual filament bulbs are fitted, 5w/21w, both filaments are not used - either the 5w filament or 21w filament is used depending on where it is.
Your lights work the same as mine and is normal as far as I can see.
I think in the USA they were wired to use all of the filaments and looked very pretty across the car but the UK cars (at least mine) are not configured this way, that's the conclusion I came to anyway.

See this for the whole story, its started with no brakes lights after doing some other work which sent me on the wrong fault finding path. Anyway, in the end it was 1 or 2 blown bulbs, plus one of bulbs which was a single filament bulb forced into dual filament socket.
 

 

[Chinesetuba]

I feel better that your lights are the same. I've had the car over 10 years and can't remember what's supposed to light up 😏. Seems strange that the wiring, holders and bulbs are there but they don't work. The USA models do look better all lit up, I may do some splicing...

[Malc1]

4 minutes ago, Chinesetuba said:

I feel better that your lights are the same. I've had the car over 10 years and can't remember what's supposed to light up 😏. Seems strange that the wiring, holders and bulbs are there but they don't work. The USA models do look better all lit up, I may do some splicing...

Be careful you don’t mess it up for the MOT rules 🤔

Malc 

[Chinesetuba]

I don't know what infringement it may be but the more lights the better, in my opinion.💡

[Razor61]

34 minutes ago, Chinesetuba said:

The USA models do look better all lit up, I may do some splicing...

I thought the same thing but didn't know how it would affect the Lamp Failure Sensor module, different part number for USA spec Lamp Failure Sensor module as opposed to Europe spec.
I guess for the USA spec the 'internal' configuration is different, maybe a USA 'spec' Lamp Failure Sensor module would fit and all the lights would work.
As to why they are different, maybe there is some EU law about how bright/how many lights are allowed on the rear of a vehicle - it wouldn't surprise me.

[Malc1]

46 minutes ago, Chinesetuba said:

I don't know what infringement it may be but the more lights the better, in my opinion.💡

But your ( perhaps ill informed ) opinion might not agree with the MOT strict criteria on rear lamps ……… as a preliminary to doing work like this perhaps it would be astute to seek the advice of an MOT Tester upfront 🤔

Just a thought 😄

Malc 

[Razor61]

MOT test states for the relevant bits:

Front and rear position lamps
Vehicles must have 2 front and 2 rear position lamps, except for tricycles or quadricycles that are less than 1,300mm wide.

Stop Lamps
must have 2 stop lamps, one on each side.

Stop lamps exceptions similar to the position lamps, less than 1,300mm wide etc.
Maybe it's the number of lamps that is the issue, it doesn't state 'at least' 2 lamps so maybe it 'has' to be 2.

[Chinesetuba]

Thanks, I'll check with them. Where are the fuses for side and brake lights btw. Couldn't see anything in the box under the bonnet.

[Herbie]

.

[Chinesetuba]

In each light unit there is a double filament bulb at the top and a double filament bulb at the bottom. There is a single filament bulb in the middle for the indicators. My point is why use a double filament fitting with all the wiring but only perform one task, or is there a fault somewhere?

[Razor61]

It’s more cost effective for the manufacturer to have the same wiring loom and fittings for all models/configurations and just not use some of the wiring/functionality rather than manufacture different wiring looms and fittings for each model/configuration.
In this case I think it’s the Lamp Failure Module that is internally configured differently and some other bits maybe, cheaper to have different Lamp Failure Modules and other smaller bits than different wiring looms and light fittings.
A member on here checked his rear side lights and stop lights, pictures weren’t great but good enough in the end to prove it was the same as my car so that was it for me. This was after a few days of chasing my tail with a power probe, multimeter, examining wiring diagrams and a lot of head scratching and frustration. I got obsessed with an ‘issue’ that in reality didn’t exist.

[Chinesetuba]

Thanks for that. Can't believe I've only just noticed this issue after ten years! Perhaps I did notice when I first got it but old age has dimmed the memory 😊

[Spock66]

I would have thought the MOT regs would also specify the bulb type / brightness etc as you need to be able to differentiate between Position Lights, Brake Lights & Fog Lights.

[Malc1]

3 minutes ago, Spock66 said:

I would have thought the MOT regs would also specify the bulb type / brightness etc as you need to be able to differentiate between Position Lights, Brake Lights & Fog Lights.

Plastic lens colours would do that to some extent maybe 🤔

Malc 

[Razor61]

Side lights on



Brake lights on

[Razor61]

After taking those photos, no lights on the boot and I think there should be when the sidelights are on. I seem to remember on my 95 LS400 there were lights on the boot lit when the side lights were on. When I had the 95 LS400 my son in law ended up following me down the M66 early one morning, took a picture and sent it to me, he was the passenger, and I vaguely remember lights on the boot. Can’t find the pic now though.
Some investigation needed at the weekend maybe.
Could someone confirm whether the lights on the boot should illuminate with the side lights on please?
When I was checking and sorting the initial ‘no brake lights issue’ the boot was open so didn’t look at the boot lid lights while testing etc.

[Razor61]

My memory is working again and I think the lights on the boot are only the rear fog lights and reverse lights not side lights as well but if someone can check and confirm it I would be grateful🙂
Son in law maybe took the photo when I had the rear fogs on and I probably checked all this a while ago and forgot, the memory isn’t what it was and takes a while to warm up and function🤣