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Hi

I have a 2018 Caddy life 1.4 petrol.

I am new to this caddy, I have noticed when the headlights are on, the side lights are off, I had the assumption they would both be on together.

It has the 21w 5w bulb to share the drl function, when I put my side lights on the 21w drl is still on, but when I flick it to the headlight the side light bulbs are completely off.

I have just upgraded to the Halfords 200% brighter to replace the factory candle lights lol but I would like the side lights on as well to to squeeze that extra bit of light out.

Is this normal on the caddy. I have plugged the diagnostics on and did an output on the side lights and the 5w light came on, so it appears the wires are working from the bcm. I couldn't find anything on the coding list that can change to allow parking lights with head lights.

If anyone has any advice with this, or know if this is a standard feature for the caddy.

It's a coding thing. If you have VCDS or OBD Eleven, go into BCM coding and you should be able to find an option that enables the sidelights with the main beam. I cant remember where exactly that option is

This is normal behaviour. DRL and sidelights go off when the main lights are on.

21w Headlights off & 5w Headlights on is correct for DRL’s

21w DRLs on, 5w sidelights on, headlights on DRLs and front sidelights go off. At least that's what my facelift Caddy does, and always has.

Giddy wrote: ↑Sat Dec 20, 2025 10:39 am It's a coding thing. If you have VCDS or OBD Eleven, go into BCM coding and you should be able to find an option that enables the sidelights with the main beam. I cant remember where exactly that option is

Thanks, I've had a look through on obd eleven but couldn't see anything, I'll have another check

STP wrote: ↑Tue Dec 23, 2025 1:28 am This is normal behaviour. DRL and sidelights go off when the main lights are on.

Thanks

hatman wrote: ↑Tue Dec 23, 2025 7:23 am 21w Headlights off & 5w Headlights on is correct for DRL’s

Thanks, I've noticed on mine, with the side lights on, it's still on the 21w, but the 5w will only come on with an output test on obdeleven :s not sure if this is standard too.

STP wrote: ↑Tue Dec 23, 2025 9:59 am 21w DRLs on, 5w sidelights on, headlights on DRLs and front sidelights go off. At least that's what my facelift Caddy does, and always has.

Thanks

Iv just checked back my pics b4 i fitted my bi xenons and my drl’s were defo on with the headlights and stayed on with main beam aswell if memory serves me. Could be a coding issue. Hope iv not chucked a spanner in the works guys.

Mine was a work van from new before I bought it from the company so had never been coded or messed with. The behaviour I get is as it was from new.

As soon as I put sidelights on, the DRLs dim to a low value and the tail lights come on too. When I switch to headlights, the DRLs/sidelights at the front go out and the headlights come on dip beam, tail lights stay on of course.

I coded dips to stay on with main beams - but the DRLs have always gone off with headlights on.

Mine is an 18 plate mk4 and had single H4 bulbs in each headlight. Is urs a mk3 STP? Mine was a company van aswell b4 i got it so dont think it had been coded either.

Mines a facelift MK3 mate, 2015 and same h4 lamps. I have put LEDs in the drl slots, Philips Ultinon and they work, but with the usual dashboard error. Have to swap them back today for MOT. Will see how it behaves with the standard bulbs back in.

The Philips LEDs have the dual bright/dim function just like the original ones, I did it so early on that I can't remember how it behaved with normal bulbs. Look so much better though. I have VCP, VCDS and VagHelper, going to try coding them to LED once I get through the MOT.

So I fitted the standard bulbs, passed MOT with flying colours, no advisories. MOT tester guy said "your van is minted btw" - nice one. And I tested the lights again with normal bulbs in and same result, DRLs / sidelights go off when main headlights are on.

I just remembered - way back when I first got the van I coded the cluster MFD to Rest Of The World (ROW) so I could get the digital large speedo in MPH which works perfectly, and am now thinking that is why the sidelights go off with main headlights on. Must be a ROW setting.

It seems you need to go to 09 - Central Electrics and set byte 21 to the value "20" which is "Parking lights with low beam" and "Dimm with low beam"

Not done it yet, will try later today, and this may be your issue too @Franko