1994 Ls400 Headlight And Rear Fog Light Problems

[garagestmarien]

Hello all.

I am John, British but living and working in Holland.

I have a 1994 LS400 Series 1.

It failed it's dutch MOT (APK) on rear fog lights and worn rear brakes.

Fog light switch was broken, so found one on eBay but waiting for it to arrive. Made a tempoary switch and new wire to make them work for now.

Went back for retest and the headlamps have stopped working.

I have checked the fuses and relays and bulbs. All are okay.

The headlamps flash with and without ignition, the side light work. But with ignition on and head lights turned on, nothing, no main beam eith only with the flasher.

The height motors don't work either, but again they do when the flasher is operated.

Everything was working fine up to 2 days ago, so I have no idea what has happened.

I can't find a wirinf diagram that shows european wiring, only USA and Canada and they don't seem to have manual height adjustment, twin from lamps or even rear fogs.

If I could get a wiring diagram maybe I stand a chance.

The only solution I can think of, is to completely rewire them.

Unless anyone has any ideas of what has happened.

Apart from this, this is the best car I have ever owned and don't see myself driving anything else in the future.

[ROYT]

Did you check the headlight relay in the big fuse/relay box under the bonnet?

There is a 7.5 fuse in the circuit but I cannot remember where, did you check all fuses in the fuse/relay panel near the accelerator on the right? [right hand drive]

[garagestmarien]

Yes mine is left hand drive, but I checked the fuses near the pedal. All are good.

The headlamp relay works when the flasher is pulled.

All I haven't got is headlights and high beam.

All fuses under dash and in engine bay are good. I have checked them all with a multimeter to be sure.

I don't know where the wiring goes from the column switch.

Does it go to the headlight relay under bonnet or somewhere else first?

[ROYT]

Do you have the 'dimmed headlight' system on your car?

[ROYT]

there is a relay for the rear fog lights in the boot.

[steve2006]

If you PM your email address I will send you the wiring diagrams for the headlight circuits.

[garagestmarien]

Thank you very much Steve.

@ROYT. No dimmed headlights and there is no sign of a relay in the boot on either side. I have seen a diagram showing this, but on mine, nothing.

Got my new rear fog switch today, really fast.

I notice it is a rocker type, where my broken one was a push in for on, push in again for off. (Like a ball point pen). Stripped it down and very flimsy design, so the rocker one I think will be much more reliable. 9 Pound plus postage for the block with mirror switch, headlamp height adjuster and fog switch. Nice result.

Now I only have to figure this wiring out.

Can't be too hard as from what I can see the switches are all earths with the live being on the relay to the lights. Which also makes me think, I could not have shorted anything out.

[garagestmarien]

I have not had time due to work to check yet, but from the wiring diagrams it looks highly likely that my Integration relay is at fault.

I have to remove it time permitting and check it out.

I have read that a resistor can blow with the wrong bulbs fitted and other things and maybe wiring in a new rear fog light circuit has caused the problems.

Once I can get it off and checked I will report back.

[garagestmarien]

I have finally taken the integration relay off.

Opened it up hoping to find a resistor problem, but have found a small transistor burnt out (more like exploded).

I now have a new question.

Do I need this relay.

I don't have auto headlights, I don't have dimmers or anything else that I see should be with it.

Is there a problem bypassing it?

[steve2006]

I have a good secondhand one for a 1993-1994 LS400 as I blew mine up fitting cheap LEDs.

Of course it was slightly different for my JDM Celsior model so I repaired my original with the usual burnt out resistor and still have this replacement.

If you are interested in aquiring it send me a PM.

Not easy to bypass as nearly all the interior and exterior lights pass through it, just check for short circuits, cheap LEDs and water ingress before fitting a replacement.

My post below.

http://www.lexusownersclub.co.uk/forum/topic/82853-integration-relay-repair/