Daytime Running Lights issue

Cathal · March 25, 2018

Hi,

I have a 2014 IS300H Sport. When the car is turned on only one of the daytime running lights works.

I've checked the fuse box in the engine bay and checked the fuse board in the passenger foot well. I can seem to find anything that related to DRL.

Is there a fuse for these lights? Are they fused individually? Or are they run off some module? Is it possible that the fitting itself has failed?

Thanks

ColinBarber · March 26, 2018

I don't believe these are individually fused, each has a direct connection back to the semiconductor power integration ECU. I'd suspect the wiring and/or LED light unit itself.

Cathal · March 28, 2018

Many thanks for the reply Colin. I suspected something like this.

I suppose best way to find out is to take out both DRL and switch them over to see if the one thats working works when its plugged into the one thats not.

Is it difficult to get at these lights? I suppose there is only one way to find out.

sorcerer · March 28, 2018

Instead of taking them out just measure the voltage at the working one and provide an external voltage of the same value to the faulty one.

Cathal · March 28, 2018

5 hours ago, sorcerer said:

Instead of taking them out just measure the voltage at the working one and provide an external voltage of the same value to the faulty one.

I'll try, but it looks like the connections are hard to get at. Can hardly fit my hand in.

Is300h lexus · September 3, 2020

Hello,

Did anyone have any luck with the day time running light? I have a lexus is300h and the passenger side DRL has gone off and I cannot find a fuse related to the DRL any advice?

Herbie · September 3, 2020

44 minutes ago, Is300h lexus said:

Hello,

Did anyone have any luck with the day time running light? I have a lexus is300h and the passenger side DRL has gone off and I cannot find a fuse related to the DRL any advice?

As Sorcerer said above - measure the voltage at the working one and check to see if that same voltage is at the non-working one. If it is then you know it's the LEDs themselves that are faulty. If there's no voltage there then you have a problem in the wiring that you need to start tracing back.

Is300h lexus · September 3, 2020

Hi thanks will give that a go.

200h · September 3, 2020

here is an advert for a used running light

if you have a look at the images you will be

see the type of plug you will be looking / feeling for

Jandb · September 24, 2020

How did you solve this problem? Seems to be a bit of discussion around failing DRLs on the US forums as well.

Mikey B · January 16, 2021

One of mine has gone out to.......not cheap to replace :-(

200h · January 16, 2021

https://www.ebay.co.uk/itm/Lexus-is300h-is250-Daytime-Running-Light/164613599974?hash=item2653bc32e6:g:n3UAAOSwW0Bf6x0z

the link above is for an IS300h as you said not cheap £250 2nd hand

Imranali · December 6, 2021

Hi anyone successful to fix the problem. Mine went out last night.

Maxz · December 8, 2021

Not a solution as such, but if you just want “symmetry” and not spending £250 to replace + labour costs, just use Techstream (from £25 a cable) or have a garage/dealer switch off the daytime lights altogether.

ColinBarber · December 8, 2021

1 hour ago, Maxz said:

Not a solution as such, but if you just want “symmetry” and not spending £250 to replace + labour costs, just use Techstream (from £25 a cable) or have a garage/dealer switch off the daytime lights altogether.

It's been a while since I owned an IS300h but I thought the DRLs were also the front position 'side lights'? If that is the case then disabling them would make the car unroadworthy and it would fail an MOT. If the vehicle has separate front position lights then it would be ok to disable DRLs for vehicles registered before 2018.

Maxz · December 9, 2021

On 12/8/2021 at 8:29 PM, ColinBarber said:

It's been a while since I owned an IS300h but I thought the DRLs were also the front position 'side lights'? If that is the case then disabling them would make the car unroadworthy and it would fail an MOT. If the vehicle has separate front position lights then it would be ok to disable DRLs for vehicles registered before 2018.

Not sure about 2018 onwards but for a 2014 the sidelights are separate from the DRL, so Techstream has the disable option. Anyone nervous about a DIY adjustment of settings, you can pay the dealer to do instead.