LS400 headlight issue

[hockeyedwards]

Now then! (General Melchett tone), I have been reinstalling front and rear lights this morning and went round testing everything to make sure everything worked and have a seemingly odd dipped beam issue. As far as I can recall, everything was working before it headed to the bodyshop, not that anything they could have done would influence this.

When I turn the stalk to dipped, neither side comes on, however when I push the stalk forward for high beam, they both illuminate alongside the high beam.

I have checked fuses, relays, bulbs and there would seemingly be power getting to the bulbs, just not at the desired time. Would the indicator stalk itself cause the issue? I even tried setting my phone up to record the lights whilst I had a waggle around to see if I could coax them back to life, but no dice.

Any insights, suggestions, words of wisdom? I am hopefully going to get ahold of a spare stalk to test my theory, but wondered if I could do anything in the mean time?

[BigBoomer]

Sounds like a relay somewhere is not operating.
I believe yours uses an H4/9003 in the main headlight for both low and high-beam and a HB3/9005 for the spotlight that is alongside the headlight.
So, either the relay powering the low beam side of the H4s is not working or else both H4s have blown their low beam filament.
 

[hockeyedwards]

Yes definitely H4's and pretty sure HB3's. So maybe bad luck and as you say both bulbs have blown one filament each. I will grab some brand new ones tonight and swap them out and inspect/ see if that makes a difference. Because the bulb came on with the click forward on the indicator stalk, I had presumed it was good, forgot it had two filaments, seems odd that both would go a once whilst in storage and have been undisturbed for months, but hey ho!

On the relay side, I did swap some over to check if one had blown, how many relays are there for headlights?

[BigBoomer]

11 minutes ago, hockeyedwards said:

On the relay side, I did swap some over to check if one had blown, how many relays are there for headlights?

Sorry, my LS430 has HIDs and 9005s for high beam so a different arrangement since the HID is always on and it just adds the high beam lights.
However, I would imagine it will be one relay for the 2 dipped beam filaments and another for the 4 high beam filaments.
The stalk switch will choose between energising relay 1 (low) or relay 2 (high).
That was how my 98 Legend worked.

[hockeyedwards]

Just now, BigBoomer said:

The stalk switch will choose between energising relay 1 (low) or relay 2 (high).

No problem. Ok that has clicked in my head and makes sense, but I did swap a like for like relay and issue still presented itself, maybe I've been dumb all along and the bulb was the culprit, will find out soon enough 😛

[Malc1]

Kieran hi, you hopefully just need new bulbs and if you're using the regular standard bulbs they're ( or were ) about a tenner the pair from Halfords ..  they even only charge a nominal sum to change them too .  BEWARE, there's  2  bulbs in the pack so you only need the one pack !

Malc

[hockeyedwards]

Thanks Malc, they were 7 of the Kings pounds for a twin pack! Fortune would have it, I was a 'fitter' whilst working for Halfords at University and I would hope after stripping the subframe, suspension and interior, I could manage a mere bulb change (he says) 🤣 - time to find out 😛

[hockeyedwards]

So after all of that, it was the sodding bulb, serves me right for not sticking to simple things first, both bulbs visibly blown on the dipped beam filament. Halfords will have to do for now and I will upgrade later as the light given off is abysmal, must have been bad luck that both went together.

[Malc1]

2 hours ago, hockeyedwards said:

must have been bad luck that both went together.

or good luck that you got max value from the pack of TWO  🖕

Malc

[steve2006]

Not long after I bought my 1994 Celsior I converted to HID headlight bulbs, no problems after the garage I use for MOTs adjusted them.

Just before selling the car I changed back to the original halogen bulbs which I had wrapped up in kitchen roll and stored in “the shed”

Given they were by now over 25 years old they still worked!

[hockeyedwards]

45 minutes ago, steve2006 said:

Not long after I bought my 1994 Celsior I converted to HID headlight bulbs, no problems after the garage I use for MOTs adjusted them.

Just before selling the car I changed back to the original halogen bulbs which I had wrapped up in kitchen roll and stored in “the shed”

Given they were by now over 25 years old they still worked!

Haha amazing!

Tbh I am pretty miffed as the bulbs were only 2 years old and only had like 6 months use!

[BigBoomer]

A friend used to go through 2-3 H4 bulbs every year on his motorcycle (Kawasaki Z1R) and about the same number of brake light bulbs. Finally he had enough and started investigating. He discovered that the rectifier/regulator was FUBAR and was putting out over 15V with a heavy AC component despite the "smoothing" properties of the Battery. A new alternator (rec/reg is built into it), new Battery and new bulbs and the problem was sorted. The high voltage was obviously over-heating the low beam and tail light filaments and in a motorcycle the suspension is a lot stiffer than most cars so the jolting broke the overheated filaments.
Yes, some bulbs are built down to a price but even quality bulbs can get killed by abuse.

On my GTR1000 the headlight LED "bulb" is now 10 years old and going strong. It has a perfect pattern, is not too bright and does not dazzle oncoming traffic but provides massively better illumination of the road ahead,... nearly as good as my LS430 which is good considering it is a 1980s design Fresnel headlight and only has the single headlight.
My GTR1400 is still on the OE headlight H4 bulbs after 16 years and 77k miles.