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Dim Instrument Lights

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Hi all,

I've got a 2000W IS200 SE with 39k miles on the clock.. I've recently noticed that the instrument lights in the speedo and on the centre console are a bit dim at night on idle, but when I press on the throttle, it all brightens up again. Has anyone had this issue before???

I've been to 2 seperate dealers (Edgware Road and Croydon) and they both said they "fixed" it, but a day later it's exactly the same!! Ok, so maybe a 4 or 5 year old car might have this problem, but mine is less than 3 years old and bought from Lexus Canterbury! I would go directly to them if I could, but it's a good 2.5 hour drive away..

Should I go to other dealers?? or keep pestering the ones I've already taken it to? Bearing in mind that the original warranty runs out in March (I've got the approved one till November), I'd like to get this thing fixed!! Croydon replaced the alternator, but made no difference..

Thanks for any info/advice!! :blink:

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have you had the Battery checked out? i know it is only a real small drain but with the lights etc on the Battery may not be able to supply enough, if you are getting roughly 13.5 volts (give or take a bit )when the engine is running then the output from the alternator is ok. Also dont check the Battery voltage just after switching the car off - you will get a false reading , leave it for 5 mins then try

We used to do a test involving trying to start the car when in first with the brakes on,

(dont recommend you do this though) you could then see how much the Battery could supply, only did it for a second or you get problems with overheating - if the Battery voltage was really low then it was time to get a new one!

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well, both dealers checked the Battery and said it was working fine.. as I said before, there's also a brand new alternator in as well. Surely I can't be the only owner in the forum to have experienced this. I hope not! :sad:

I'm by no means an expert in electrics, but would a higher capacity Battery do the trick? or is that not getting to the root of the problem? could it be a fuse issue?? Calling all anoraks! Help!! :crybaby::crybaby::crybaby:

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Surely I can't be the only owner in the forum to have experienced this. I hope not! :sad:

Your the first person I've heard mention it and most things to do with the IS have been discussed here!

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Presuming all lights (not just the panel) are affected - could be your idle-speed is too low.

Does it do it in D or Neutral or both ?

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I have a Jan '01 IS200 SE and I notice a similar 'event'.

Mainly when car has not long been started on idle the lights are dimmer, also notice this (even more so) when the rear demist is on, or in summer when the air conn kicks in.

Just out of interest, when I look at my dig. mileage readout, the display is brighter on the left side, where ODO or A/B is, then on the right where the miles are recorded. Does anyone else see this?

Regarding the original point, I put this down to life, it may dip slightly as demister and lights will load the Battery. It should not be excessive though. After a run it should be ok - have only really noticed when engine relatively cold. (sort of makes sense as the oil will be thicker so more resistance in the motor, therefore greater strain etc). All the alternator does is charger the Battery.

What is the IS200's Battery capacity? Have you also noted what the Battery Voltage meter does when your lights dim?

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Lexicon,

it happens in both D and neutral..

kev dood,

I know what you mean when it dims a little when turning on the rear demist, but the problem occurs quite often (during night driving only obviously). And YES, I have the same thing with the odometer display! left side is brighter than the right!

I haven't really noticed any unusual readings from the voltage meter, it doesn't really change when I accelerate and brighten up the instruments.

Although I'm somewhat relieved that someone else has had this issue, it does seem strange that kev dood's car which is only 2 years old has it as well.. <_<

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All the alternator does is charger the battery.

Not strictly true - the lights should always be brighter with the engine running as the output voltage from the alternator is higher than the Battery (by about 2v).

You will always get dips in voltage when switching on a heavy electrical load (HRW etc) or the revs drop momentarily (AC compressor switching on etc).

Maybe if your idle speed is low you aren't getting enough juice from the alternator.

What does your voltmeter read? Should indicate about 14v under "normal" conditions.

Of course, if you have everything switched on then the voltage will fall away at idle anyway.

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Lexicon is dead right - the alternator provides more power to the system.

Do you have this effect if only your side lights (not main beam) and nothing else is on? (Hrw, blowers, etc.)

If so, I would definately say your idle is too low as well. If you know anyone with a Multitester (preferably digital), measure your Battery voltage with the engine idling. It is set at 13.8v from the regulator in the alternator. (I'm not being pedantic Lexicon!)

You may have a slight voltage drop at low revs which is noticeable but not critical to the operation of the car or charging of the Battery.

Do you need to increase the revs by a few hundred, or just a light touch on the accelerator for the difference to be noticed?

I know it's hard to tell exactly, but what is the car idling at? If the revs are lower than normal then it would just be a trade off against idle revs and voltage level.

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ok, will get back to you guys about the figures (idle speed, voltage, side light only, etc).. have to wait till it gets dark though cuz I ain't got a garage! :(

what I know for sure is that it doesn't always happen, but when it does, it's b****y annoying! in the meantime, I'll put the idle speed question to the dealer and see what he says..

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I've had a close look at the instruments over the weekend and these are my observations:

1. On cold, the engine idles at around 1,250rpm (no lightings probs)

2. When warmed up, the engine idles at about 750rpm (dim lighting)

3. Warmed up voltage is about 13.5v

4. Upon revving gently, voltage slowly goes up to 15v or so and then slowly goes back down to 13.5 and lighting goes back down proportionate to that change.

I've booked the car in with Lexus Croydon again (the ones who changed the alternator) for the 10th of Feb. This time I'm gonna make the guy come in the car with me and show him exactly what I mean. Hopefully, it'll be a cloudy/dark day! :ph34r:

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That all sounds about right - the voltmeter on the dash is heavily damped so it will react slowly to changes.

If you can get your hands on a digital voltmeter you can get a more accurate reading because if it is really going up to 15v that might indicate a problem with the voltage regulator (but that's in the alternator anyhow).

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Just to let you know, I went to Lexus Croydon yesterday to have a look at it, fully expecting to take the train back home and be without the car for a day or two.. I insisted this time that someone come into the car and see for themselves. One of the guys comes out, switches the engine on and off repeatedly about 10 times in a row, and notices the voltmeter gradually go down to about 9v.. He said the Battery's probably too weak, and offered to replace the Battery under warranty! Good thing he did cuz my warranty runs out in a couple of weeks!

The best part, of course, is that the problem has disappeared!!!! :yahoo::hehe::yahoo:

Thanks guys for all the advice/info!!

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Glad to hear it's sorted.

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