[gurninman]

I have a 2010 i30 CW , and am having a problem with the brake lights on the nearside
One of the bulbs was out a month or so ago , so I replaced it and all was well.The missus noticed there were no brake lights that side the other day, so I dutifully popped the cluster off and had a look at the bulbs.Both looked fine , but I swapped them with known good ones anyway.Still no good.
The brake light switch must be OK, as the high level light works as do the ones on the offside
The rear running lights are fine, so I can probably rule out a dodgy earth.
Any more ideas ? I've seen mention of resetting the BCM - is this just a matter of disconnecting the battery for a bit , or does more need to be done ?

[Dazzler]

Disconnecting the - tive terminal of the battery for 30 minutes + should reset the BCM, but can't see that fixing your problem. Almost certainly a  connection or earth issue IMHO.

[Phil №❶]

You need to remove the offending light cluster and check with a multi meter the globes themselves. If there is no continuity, then the globe is faulty. If there is continuity, then you'll need to check that there is voltage at the sockets. Be careful not to short out the little terminals at the base with the earth, as you will blow your light fuse. You will need a volunteer to press the brakes etc.

[gurninman]

So, driving home from work yesterday, I foind somewhere I could test the brake lights where I could see them, and both sides are out.Have tested both sides today , and the bulbs / clusters all test good.The high level light works , the tail lights work, as do the reverse lights and indicators.Just the brake lights.Surely if it was an earth issue , then none of the other lights in the cluster would work.
I saw a thread on here where a guy had an i30, took it to the dealer and they did a BCM reset which fixed the issue - seems to be the same problem I have , which is why I thought about resetting it.

[Phil №❶]

Can you tell me how you tested the brake filaments and the clusters.

[Dazzler]

So, driving home from work yesterday, I foind somewhere I could test the brake lights where I could see them, and both sides are out.Have tested both sides today , and the bulbs / clusters all test good.The high level light works , the tail lights work, as do the reverse lights and indicators.Just the brake lights.Surely if it was an earth issue , then none of the other lights in the cluster would work.
I saw a thread on here where a guy had an i30, took it to the dealer and they did a BCM reset which fixed the issue - seems to be the same problem I have , which is why I thought about resetting it.

It's certainly worth a try. Have you had your brake light switch done under warranty?

[ibrokeit]

I am not going to discount anything that was said already - they might be the fix...  and the situation seems slightly odd.

However this might be a case where the contacts in the holder need a little 'tightening' to make a better connection to the bulb - generally this means bending the connector (made of a small flat thin piece of metal positioned so it is under tension when the bulb is inserted - e.g. sprung) in towards where the bulb sits.  It would be possible that two bulbs, or rather the contacts, doing the same function could develop the same issue at approx. the same time due to equal-loading.

I have ran into it occasionally on vehicles, and other varied devices, usually the conductors that contact the bulbs appear 'burnished' (e.g. discoloration - usually bronze and/or blueish).  It seems to result in non-conduction presumably due to seemingly light oxidation, and often the cause seems to have been 'light' contact of the housing conductors to the bulb.   I am guessing that and repeated heating/cooling cycles allows the oxidation to 'grow' between the metal surfaces.   Often I have been able to fix it quickly (possibly permanently) by just bending the contacts (if possible) so there is a more firm connection between them and the bulb.

In fact I did that only two weeks ago on good friend's car - his Dad (who knows 'this stuff' - e.g. cars) is out of the country for a number of weeks - one of the lights wasn't working (think it was indicator) but the bulb wasn't blown (unfortunately I was asked to look ad-hoc so I didn't have my multimeter with me - instead holding into a different holder to check).   The contacts were discoloured and bending to give a firmer connection fixed the issue.


As an aside about the BCM fix - not saying it won't/doesn't work... just that I can't figure out why the hell it should work (if it does)...

I would have thought the LED bar wouldn't be working as well if it was an issue in the wiring (rather than bulbs and/or holder connections) - presumably they would be all supplied by the same wiring... however maybe they are not for redundancy and are wired separately back to the BCM (hence the report of a BCM reset fixing it).   However I am not sure why, in an i30, the switching would be done by the BCM instead of directly by the brake pedal switch... after all they are not 'F1' racing cars which flashes a red light for a) indicating energy harvesting (usually associated with slowing); and/or b) low-visibility (e.g. rain, fog, etc.) - in any event such control could be done in parallel with the switch (rather than instead of it).

Having said that - I didn't do the design nor have, yet, to get one of the shop/service manuals to see how they are wired.

[Dazzler]

However this might be a case where the contacts in the holder need a little 'tightening' to make a better connection to the bulb

This could indeed be the case as I just did this with the connector for Trish's boot light in her GDe Tourer which was not coming on. Bent he pins slightly to make them snug and did a little squirt of RP7 to improve the connectivity.