The Dangers Of Replacing Bulbs With Leds!

[steve2006]

A short while ago the little capless bulb that illuminates the ignition lock finally failed after only lasting 19 years!

Rather than replacing it with an old fashioned luminaire I decided that a blue LED would look nicer so purchased a pack of 10 from that well known auction site for a few pounds.

I installed this one and also the footwell lights and all was good, infact it looked quite snazzy.

On Sunday it was a nice day so the LS got the works..vacuumed and cleaned inside and then wash and waxed outside.

It wasn't until later when I decided it was time to put it in the garage (It has to be in the garage by 10.00pm when at the house for insurance purposes) I discovered that the ignition lock light, both footwell lights,dome light and the outside driver's door lock illumination were no more.

The dome light came on normally when switched to on but not on the door position.

The next day armed with the circuit diagram diagnosis began and it would appear the problem is a defective "Integration Relay" a little computerised unit which amongst other things controls the lights now not working.

A bit more research revealed that faulty bulbs,short circuits on the bulb holders and DUFF LEDs can cause this unit to fail.

On top of a cost of £400.00 from Lexus the thing is located on the rear of the interior fuse panel so access is a right PITA.

I am therefore taking the 2nd hand route and presently looking to source one.

So the moral of the story is if a bulb is sufficient for 19 years another bulb is the way to go and not cheap LEDs.

[Maduggo]

Very sad tale indeed.

This is the downside of the LED market, you can get some real crap ones capable of causing damage. I don't think it is related to price of the LED's either.

I would venture a guess at some normal bulbs could be capable of causing damage too.

The moral of the story should be a lesson to us all, change out OE items at you risk

[turtelshead]

Did you manage to change the said unit Steve as just changed the master cylinder(Tweety pie noise) and not having any foot well lights done the same as yourself spare leds swop them in the foot well lights now find myself with the same symptoms as yourself so just wondering if you ever got round to fixing it.

[ambermarine]

The mixing of electrical parts is tantamount to playing with fire .As a guide to how good the electrical system on the Lexus LS400 is here is a history of my late Mark 1. In the 22 years I knew the car it never had a light bulb fail the only failure was the lcd display on the temp readout not electrical but seal failure.Now one might assume that this non failure of light bulbs is due to the quality of them ,partly but in essence it is the design of the circuitry and its built in voltage and ampage safety devices that is the key,so if you intefere with those tolerances and settings with lesser or more then problems will ensue.This is one of the reasons I have and never will add non oem accessories or electrical parts to any of my Lexus cars.

[cleverdick]

I don't know which LEDs you bought - whether mounted in a bulb cap or not - but in its most basic form an LED is most certainly not a drop-in replacement for a bulb.

An LED will have a specified maximum current rating, and, depending on the colour, generally drop about 2V at its normal operating current (maybe 10mA or so). Consequently, you have to select the appropriate resistor according to (1) the supply voltage, (2) the desired current and (3) the power that will be dissipated in the resistor. In 'bulb form' you have to assume that the manufacturer has done all this correctly. It also goes without saying that an LED is by definition polarised and thus will only work one way round.

You may find that reinstating the original lamps restores correct functionality.

Hope this helps.

[steve2006]

Did you manage to change the said unit Steve as just changed the master cylinder(Tweety pie noise) and not having any foot well lights done the same as yourself spare leds swop them in the foot well lights now find myself with the same symptoms as yourself so just wondering if you ever got round to fixing it.

Yes I did sort it but not by replacing the unit as once again the one I bought from a 1994 LS400 was different to the one in my 1994 Toyota Celsior.

Once I removed the Integration Relay from mine ( pig of a job!) I opened it up to find a fusible resistor burnt out ( as they are supposed to do to protect the circuit).

I replaced the resistor and it all worked once reconnected and having made sure all the naff LEDs were removed and replaced with conventional bulbs.

If you have the 1990-1994 LS400 I still have the correct working unit I bought if you are interested making it more plug and play