2018 Yaris Hybrid DRL confusion

[AlunS]

So, my wife's Yaris Hybrid is due it's first NCT (Irish equivalent to the UK's MOT) soon, so I've just done a quick all round light check to save any embarrassment on the day, and I've discovered the DRL's don't work.

A bit of background ... it's an Irish spec Yaris Hybrid, registered at start of 2018. It has no Auto lights, despite the manual showing this as the only option, and as far as I can make out has no LED strip anywhere in the headlight cluster, so assume it would use either the sidelight or fog light bulbs as DRL's.

I've opened up the fuse box in the engine compartment and there is a DRL fuse, which tests OK, and a DRL relay. If I take the relay out and turn on the ignition. there's no voltage detected across the relay coil terminals 1 and 2. The relay coil itself is not open circuit, so I assume it's working correctly.

Any ideas? Is there anything in the vehicle settings, or could it have been coded out somehow?

[FROSTYBALLS]

How did you determine the DRLs aren't working? With the engine running and the handbrake on??

On some cars the DRLs will illuminate with the engine running and the handbrake released.

[AlunS]

Ah, yes, stupid me!!! It was the handbrake being on that was the issue 🙂

Thanks!!

[Bernard Foy]

There you go Alun, I had a 2019 model, great car. Folks on here are very helpful and knowledgeable. The car will pass with flying colors.🚘.

[AlunS]

Thanks everybody, I'm not sure I understand the logic of turning off the DRL's when the handbrake is on to be honest., although I remember now that my car, a Kia Niro, does the same.

Also had a look at the bulbs and the ones in the sidelight part of the cluster seem to be dual filament, the same as the ones used in brake lights, presumably with the brighter of the two for the DRLs and the other for the sidelights.

[FROSTYBALLS]

DRLs are intended to warn other road users of an approaching vehicle - which is why some cars don't have them on whilst stationry (ie when the handbrake is on).

[AlunS]

True, but it also wouldn't be any harm to have them on all the time either, even when the handbrake is on, and somewhere there's going to have to be some extra circuitry to provide that interlock, one more thing to go wrong.

[FROSTYBALLS]

19 minutes ago, AlunS said:

somewhere there's going to have to be some extra circuitry to provide that interlock, one more thing to go wrong.

The same for those cars that integrate the DRLs with the front indicators - where the DRL turns off on one side when the indicator is on ......

[preperationlaunch]

The DRLs stay on once you've taken the handbrake off.

They only turn on when you first release the handbrake when the car is started. Which makes sense.

19 hours ago, AlunS said:

True, but it also wouldn't be any harm to have them on all the time either, even when the handbrake is on, and somewhere there's going to have to be some extra circuitry to provide that interlock, one more thing to go wrong.

It's all computer controlled by the same computer that does all the other lights, so it's just a line of code that says 'wait until you release the handbrake before turning the DRLs on when the car is started'. I highly doubt it has taken any extra circuitry for that.

[Woofwoof]

Will you fail not for non working drl?

they’re not a legal requirement

[bathtub tom]

3 hours ago, Woofwoof said:

Will you fail not for non working drl?

they’re not a legal requirement

From the MOT testing manual:

Daytime running lamps

You only need to inspect daytime running lamps (DRLs) if they’re fitted as original equipment to vehicles first used on or after 1 March 2018.

Defect	Category
(a) Lamp: (i) multiple light source up to a half not functioning (ii) missing, inoperative or in the case of a multiple light source more than a half not functioning	Minor Major