Headlights Staying On

aaronabbott · February 2, 2010

if your still having problems try replacing your theft control unit (behind the dash) which controls the lights/alarm etc it can short out,

i replaced mine and fixed the problem and a few other members have also

new666uk · February 8, 2010

if your still having problems try replacing your theft control unit (behind the dash) which controls the lights/alarm etc it can short out,
i replaced mine and fixed the problem and a few other members have also

After the fun and games I've had with mine I rang National Windscreens who fitted the new windscreen earlier in thr year and told them the problem. Straight away they booked in into the workshop for that Friday afternoon.

Turned up, watched as they removed the screen and between us we checked for evidence of the seal quality on both the body and glass. To be fair it was pretty good all the way round. They cleaned up the glass and body and refitted the screen. I wandered into town for a couple of hours to leave it to cure.

That night it snowed and the windscreen spend the next day and a half covered in snow. I've since been through rain and taken the car to the car wash and its not played up at all. That was 2 weeks ago now so fingers crossed just refitting the glass has solved the problem, might just have been slightly out of alignment.

Overall impressed with Nationals follow up customer service and that so far the lights are back under my control.

LarryD · May 11, 2010

if your still having problems try replacing your theft control unit (behind the dash) which controls the lights/alarm etc it can short out,

i replaced mine and fixed the problem and a few other members have also

Have you got exact details on how to access the acu??

aaronabbott · May 11, 2010

if your still having problems try replacing your theft control unit (behind the dash) which controls the lights/alarm etc it can short out,

i replaced mine and fixed the problem and a few other members have also

Have you got exact details on how to access the acu??

yeah if you undo the 3 screws that hold the knee guard and look up on its just behind the rear fog switch and light washer button,theres 2 control units under there its the one to the left if i remember correctly

sparkystav · May 11, 2010

You can just bypass the theft box, thats what i did.

The headlights lights wont flash if your alarm goes off but if you wire it right you wont lose anything else. cost = £0

scanner1956 · December 9, 2010

.......a quick update on the above. The door switches are all working fine. The Relay Board in the driver's footwell is perfectly dry and everything looks 'like new'. Moved all the connectors and wiring, pushed relays and fuses, etc. but the problems still remain. It has been exceptionally cold here which may, or may not, be coincidental. The engine itself runs OK.

I can't help feeling that there must be a common factor to the symptoms - headlamps switching-on by themselves, petrol gauge reading below zero and flashing, outside temperature gauge reading 'E', MPG meter not working, engine temperature gauge not working, alarm going off, security light continuously flashing..... Could the problems relate to the Anti-theft Alarm ECU unit? Can anyone say if this unit can be opened or is sealed - I am an electronic engineer and well know that many problems are simply failed solder joints, capacitors, or high value resistors. It is a different matter however if it is a failed programmable device or trouble within a multi-layer circuit board.

I intend to look at as many of the other connectors as I can find, e.g. to the Combination Meter unit (instrument dials unit), and also at the board in the passenger's footwell. Beyond that I am getting a little stuck.

If anyone can offer any suggestions, I'd be grateful.

lee200 · December 21, 2010

Ok this is whats happend with your lights water did get in to your fuse box down by the drivers feet it gets in trough the rubber gromet where the wiring loom comes in trouh the body of the car.. This happened me earlyer on this year.. How to fix it remove the plastics below the steering wheel buy a tube of good sealer ramm loads of it all around the wiring loom gromet to stop water from getting back in to your car keep the hot air blowing flat out at your feet to help dry it all out if you catch it quick you might save your fuse bord and if not then you will need to do what i had to do i had to take my car to a auto electric man he found out that my light switch was burnt out and so was a black fuse bord bok was also burnt out he got a new switch and fuse bord out of a brakers yard fitted them fom me and left my car back at me 100% total cost 60 euro dont go to lexus they will f**k you right up the ***** best of luck..

atce4 · December 29, 2010

Just been informed by a neighbour that my headlights were on. Seems same problem as others have had or are having.

Have checked drivers footwell fuse board and cannot find any evidence of water but did have my windscreen replaced last June :( Will try and check the connectors but they are recessed into the plastic kick guard (or whatever it's called!). Is it necessary to remove it before gaining access to the fuse board and connectors?

I have removed the headlamp fuses to stop the Battery going flat. The blue headlamp relay in the box next to the car Battery was making a noise but I am having trouble trying to remove it. Does it just pull out or is it held in by a clip, pulled quite hard and it seemed to be moving upwards a bit but reluctant to pull too hard as I don't want to do any damage.

Thanks

lex2oos · December 30, 2010

I dunno if this is related, but I installed HID's month ago and there is some strange thing. when I go into turn with turn signal on, when I straighten the steering wheel and turn signal stalk turns off, headligts blink. they are off very very short moment, but with hids it is very noticeable.

happened some 5 times and only with turn signals turning off. over bumps, potholes, railway crossings they have never blinked, so bad connection is quite impossible.

myb it is the stalk itself?

atce4 · December 30, 2010

I dunno if this is related, but I installed HID's month ago and there is some strange thing. when I go into turn with turn signal on, when I straighten the steering wheel and turn signal stalk turns off, headligts blink. they are off very very short moment, but with hids it is very noticeable.

happened some 5 times and only with turn signals turning off. over bumps, potholes, railway crossings they have never blinked, so bad connection is quite impossible.

myb it is the stalk itself?

Seems a strange one, never fitted HID's, is there any wiring you have done that might have caused this? Perhaps try refitting the original bulbs if you can and see if it still does it?

Back to my problem, I have been checking around the fusebox in the drivers footwell and found a very small amount of water in one of the connectors (a grey one). Cleaned it out as best I could and so far so good, but won't hold my breath.

Couldn't find any evidence of water coming in through the bulkhead grommet, all wiring seemed dry - had a friend pour water over that side of the windscreen but couldn't see anything coming through.

Hate these kinda faults, difficult to trust the car now, never thought I'd say that about my Lexus

lex2oos · December 31, 2010

Thanks!

Wiring is all stock.

I think refitting the original bulbs wont help, or I just wont see do they blink or not. the 'off' period is so short, (like a camera flash) it won't be noticeable with halogen bilbs, because they just won't turn off that fast.

new666uk · December 31, 2010

Right chaps. It's been 10 months and a good deal of rain, snow and -12 temperatures and my light issue still hasn't re-appeared. In my case the windscreen being removed and refitted again has solved this. The original relay which was buzzing enough to make the girlfriend want a Lexus is behaving as it should.

In summary, if you've had a new screen and have this problem it's worth getting them to remove, clean and refit as a small misalignment could be the cause here.

Hope it helps,

new666uk

strangey · January 12, 2011

My experience has been similar to whiteman - no problem with the headlight relay. Removed some of the lower plugs in the driver's footwell relay board and replaced them after heating with a hairdryer and a spray with WD40. Still OK after 3 weeks now - but confidence in the car has been badly shaken! The problem seems to have been linked to the extreme cold weather.

How do i do that? Is there a diagram somwhere that i can follow? thanks

grantwils · January 16, 2011

Hi folks

It appears I have the same problem on my 2001 IS200SE.

It started off with the INTERIOR GLASS FREEZING over in the cold weather we had in Nov/Dec. It was regularly -10 and even -15 around these parts and I was having to scrape the inside of the windscreen. Obviously as the ice defrosted when the car warmed up some drips must have made their way down into the electrics. I AM STILL ON THE ORIGINAL WINDSCREEN.

The first thing I noticed was the REMOTE LOCKING became a little dubious before giving up completely. The worst thing was when I went out to start it at 0700 and couldn't even get the alarm to switch off.

I then noticed that the HEADLIGHTS seemed to be coming on just after I turned the car off - they were very dull though. This happened a couple of times. I USE AUTO LIGHTS.

Eventually it got so bad that the HEADLIGHT RELAY WENT BERSERK. The headlights stayed on constantly no matter what setting the lights were at on the stock. On/Off/Auto/Sidelights the relay buzzed away and headlights stayed on. Ignition on or off, keys in or out it buzzed away. The only way to get it to stop is to remove the headlight relay in the electrics box next to the Battery.

Currently the CENTRAL LOCKING DOESN'T WORK whether I use the remote locking or the key in the door. I have had no issues with the alarm going off randomly (thankfully & touch wood).

I have removed all of the plastic panels under the dash including both footwell side panels. I HAVE UNPLUGGED EVERYTHING under the steering column INCLUDING THE THEFT ECU yet the relay still buzzes away.

Does anyone have any ideas on what I should check next? I think I have done everything suggested here but I cannot get the relay to stop buzzing at all. I could spend a fortune replacing parts but I'm sure it will come down cleaning up a couple of electrical contacts. If I can get the relay to stop buzzing then I can narrow down the location of the fault. I CAN'T FEEL ANY DAMPNESS under the dash.

I can cope without central locking but the headlights are an issue obviously. I've wired in some projectors on the fog light switch for now.

Tonymaloney · January 18, 2011

Hi chaps i am having a similar problem. My 2002 IS200 only has sidelights when ignition is turned on, headlights will not work. When you turn ignition off and remove the key the headlights come on and will not turn off unless you remove the headlight relay from the fuse box under bonnet. From reading posts on here i decided to check windscreen and cannot find made in japan so i can only presume the windscreen has been replaced at some point, i can see 'pilkington' (or at least i think that's what it says) printed on window.

My car has 'auto' setting on the stalk which does not work, also my interior lights do not work when doors open so maybe the door switches have something to do with the problem.

I am going to check footwell fusebox at weekend for evidence of moisture etc just incase, however any other suggestions would be appreciated as i would like to try as many different combinations of fixes as poss whilst i have the wknd off to get this sorted as it is completely doing my head in having to remove a relay every time i want to turn my lights off! :duh:

Cheers

HELP!! Give me my headlights back :P

grantwils · January 18, 2011

A quick update on my situation...

Left the car running with heating on full which seems to have dried out any leftover moisture. Headlight relay now doesn't buzz but I don't have any headlights. I can get full beam if I flick it to the 'flash' position but it doesn't work with the lever pushed back. Sidelights and fog lights work so I wired in a set of projectors where the fog lights were for better visibility until I get to the bottom of this.

Still no central locking or remote locking. Next step is to look at fuses. Found electrical wiring diagrams on the bahamutcars.fr link but I think I'll need a bloody degree to work it all out.

aaronabbott · January 19, 2011

sounds like the anti theft unit has blew(this controls the lights/central locking)

grantwils · January 19, 2011

sounds like the anti theft unit has blew(this controls the lights/central locking)

That's what I thought but when I unplugged the theft deterrant ECU the relay still buzzed away.

leea · March 17, 2011

hi got lex is200 2001 same symptoms as described by yall with the fault,,1st started off headlights staying on relay draining the Battery so take relay out!..went to lex dealer bolton see if could get some insight and new relay my mistake ended paying 70 quid for relay..then he said they had same lex in the dealership with same problem suprise at that point i knew it was not the relay just a quick buck for lexus...anyway searched about and found this problem is very common problem with few different solutions done all the things posted by everyone..there is no trace of damp inside the car checked fuses boards connectors and fuses cleaned also got new relay checked anti theft seems ok bleeps when unpluged no burning smell door sensors checked etc now its turned into different problem everything is working apart from headlights and headlight washers which are not!!! and i know they did work for sure!!! any ideas

aaronabbott · March 18, 2011

the theft control unit controls all these functions,get it out open it up and trace all the connections on the board.i bet 1 tiny part has blew,which if it has try and get hold of 1 from a scrapped one and refit.

even if this is removed the relay will still buzz away as there is a short on this board,it makes the whole circuit work

leea · March 25, 2011

the theft control unit controls all these functions,get it out open it up and trace all the connections on the board.i bet 1 tiny part has blew,which if it has try and get hold of 1 from a scrapped one and refit.

even if this is removed the relay will still buzz away as there is a short on this board,it makes the whole circuit work

what caused the anti theft warning unit to short? mines crispy on the little black chips Q15 Q14 on the board from theft unit

aaronabbott · March 25, 2011

a short circuit from somewhere,exactly where mine went.just ring round the breakers or best bet on eBay,some will try and rip you off but you can get them for about £25-35

if you get any more problems just send me a pm,ill be happy to help

leea · April 4, 2011

hi yall here is were im at i got another anti theft unit since mine was burnt on q14 route on the board i got a chance to have a look under bonnet of another lex and noticed a square box just behind o/s headlight? looks like a siren....is it somthing to do with the motion detectors/alarm? (2001 lex is200)

steviec_lj · June 26, 2011

Right, I got bored of quoting all of the misleading information in the thread, so here is what WILL sort out the "Headlights remain on after switching the ignition and lighting circuits off!" issues.

Quotes from the topic;

on your light switch, does this happen on auto aswell ?

theres been a case where its been the switch itself, but as you mentioned about dvd etc then best to go over the wiring from the fuse box -

It doesn't matter what position you put the switch into, the lights remain on when the ignition is off. Also, after some time the Headlight Control Relay WILL start to buzz as the voltage causes the coil to become temporarily energised. The switch IS NOT at fault!

That sounds like a relay whose contacts are welded together (amongst other things), could be 2 relays with welded contacts (lights on and dip/main) or permanently energised.

Might be worth taking the lighting relays out until you find the problem.

The relay contacts are NOT welded together, and there is only a single relay which controls the lighting circuits. Taking the relay out will solve the issue temporarily, but this isn't an ideal route!

Misleading information alert:

Note that there is an ecu controlling the lights, all the light stalk does is send signals to the ecu telling it what lights you want on, the ecu then activates the various relays concerned.

There is NO ECU controlling the lights. The ECU you would be referring to is the "Theft Deterant ECU" which controls a number of functions on the Lexus IS200, including but not limited to the lights.

what if you leave the switch on the 'auto' then switch off engine, take key out and open driver door... do they still stay on?

or have you tried cleaning the sensors on the front right corner of the dash (could be covered so lights stay on .... but then agen, should still go off when driver door opened...

puzzling that one... cant help you any further ...sorry mate

Switching to "Auto" and turning the engine off will do nothing to solve the issue.

Cleaning the sensors will do nothing to solve the issue. Removing them from the circuit does nothing to solve the issue.

Hi,

I'm having the same problem. and it only started yesterday. RAC bloke said he has re-booted the system, he thinks its some brain that tells the auto lights to come on. i'll give lexus chester a bell on monday morning to book it in. glad its under a 12 month warranty.

The RAC bloke was along the right lines. The fault that will have come up on his scanner will be something along the lines of "Headlight ECU Programming Lost". This actually refers to the "Theft Deterant ECU" which will have burnt components inside caused by shorting.

Thats right, water/moisture runs down wiring from multiplug at O/S of windscreen, and gets into fuse/relay block at drivers kick panel. Just needs a good blow out and reseal screen at wiring.

Shut up!

we've had a couple of instances where there has been water ingress into the fuse box in the driverside footwell

a replacement fusebox was needed in both instances

Shut up! The fusebox DOES NOT need replacing, Lexus Derby attempted to do this on a family members car, as they could not diagnose the problem fully. There may be oxidisation on some of the contacts, but this can be cleaned and by no means does it mean a costly replacement is needed!

Yep it happened to me ages ago cost me £200 to have the water removed and the fuse box cleaned now after the heavy rain its happened again and im gutted.

Seein more people have the same problem with many ways of fixin it is disheartening as its so expensive goin to Lexus and even they dont know half the time.

Because whoever fixed it for you DID NOT address the route of the problem.

So, you're probably wondering how to solve the issue? Well, thats what I've managed to do on a 1999 Lexus IS200 successfully for the last 2 years.

The replacement part you need is the "Theft Deterant ECU" available direcly from Lexus if you wish to pay through the nose, or you could do what most sensible people these days do, and request one from a salvage yard. They regularly come tested and with at least a 3 month warranty on them, you'll know immediately if it's good or not as it will or won't solve the issue.

Further to this, you also need to have the windscreen removed, resealed and reseated properly. RAC, Autoglass and other major Windscreen Replacement Companies ARE aware of the issue with the Lexus IS200 and the front screen heater connections on the bottom drivers side of the screen.

Rishi Handa · October 7, 2011

OK guys I had exactly the same problem and I am pleased to announce my problem was not the Theft Deterrant ECU, a leaking screen or light relay.

The problem with mine was a faulty electrical cable from the PASSENGER side, so in the UK thats the left hand side of the car, from the fusebox to the engine bay area.

The cable was replaced, 3 hours labour, and all is working OK.

So just because you have the classic scenario of the headlights are staying on after you turn the car off, isn't necessarily always the ECU/screen or light relay!

Cheers