An update and more information for those interested in the hifolutin brake light switch and associated gubbins - which I have now discovered (unsurprisingly) is also linked to the auto start-stop / cruise control switch on the clutch pedal:
I think my most important discovery however, is that the brake light switch, if believed to be faulty, can be fairly straightforwardly DIY-tested and to some degree DIY renovated by some careful dismantling, and then recalibrated during refitting. I think I saw reference to calibration during fitting in an older thread but couldn't quite understand what they were getting at.
Anyway, before dismantling the switch itself, there is a simple test without disconnecting the plug in the back of the switch. That is if you are nimble enough to feel your way up under the dash and behind the very top of the brake pedal. Up behind there, you will still need to untwist the switch from the pedalbox frame, but for the test, after twist-disengaging it from its seat, just leave it hanging on its four wires i.e. still plugged in to the loom. You want it or rather the movable plunger to be fully free and easy for you to get at and to be able to press in and out with your finger.
The first part of the test is simply to turn on the ignition. Just by doing that whilst the switch hangs by its wires, if nothing else is wrong, the brake lights should now be on all the time the ignition is on. It means that electrical current is passing through the switch, because if the switch was removed, presto - no brake lights! If you get brake lights on with the ignition, and then press in the plunger, the brake lights should go out. This might sound counter-intuitive, but when it is all fitted together properly, the top part of the pedal, which extends past the axle on which the pedal rotates, is the part of the pedal which normally full-time touches AND HOLDS_IN the plunger i.e. all the time the pedal is NOT depressed. When the pedal is depressed, the plunger which is on a simple spring inside the switch, will then be free to pop out to its full calibrated length. Only then is electrical contact made so the lights come on.
Question is, how might the switch calibrated? I think this has been touched upon in one or two other threads over the years. How do you know if it is or isn't calibrated? Well here is a picture of the switch on my 2011/12 Evo after I have reassembled it, but I can tell you that the plunger now extends too far and needs calibrating "in place" ... it currently extends about 3x the length it extended when I took it off the pedalbox:
How so? Before you go too far in following my experience further, do the test. If you cannot manually control the lights with the ignition on, just by moving the plunger with your finger, then it may not help to dismantle the switch. A new one costs anything up to €20, and you may have to order it. But even before you decide to order a new switch, it is possible your problems go beyond just the brake light switch. As I have said earlier - it seems that auto stop start, Hill-holder, ESP/ASR, cruise control all to some extent monitor messages from the brake pedal switch, but they also monitor messages from the clutch pedal switch. So think carefully before starting out. Do that simple test and establish that you can manually operate the plunger and control lights on or off, and maybe you are in luck and ready for DIY brake light switch work. Beyond that, you may quickly be in for a frustrating and possibly expensive mystery tour unless you understand auto-wiring diagrams!
One "good" thing (or at least a lesser evil in my opinion
) is that with the brake light switch removed from the car, the default situation is no brake lights. In my opinion, you are most likely to be spotted / stopped with faulty brake lights if your brake lights are on all the time! But of course if they are off all the time, you strictly are just as illegal, or perhaps more so. So if you really do choose to drive with no brake lights .e.g. to the workshop, do spare a constant thought for who is behind you and whether they are ready to stop when you are!
Right, so you've decided to press on and investigate? Removing the switch from its female London Underground logo-shaped hole, is the reverse of fitting the switch with at least one exception. For fitting or refitting, you should really hold down the brake pedal as far as you can until the switch is locked back in position.. That said, the locking male shaped protuberance on the switch (what I described earlier as having a London Underground logo type profile) is first inserted through the female same shaped hole in the moulded plastic (not metal) pedalbox main console back plate, and then it is very carefully twist-rotated by approx 30 degrees before it clicks, confirming that it is engaged and locked in place. Bear in mind that the console back plate in which the London Underground logo shaped hole exists, is just thin plastic- indeed no more than about 1mm thick at that point. Too much strength used means the specially shaped hole can be easily broken out so as to become useless, and trust me, your DIY switch change efforts will at that point have morphed into a very expensive nightmare!
Both removing and refitting can be extremely fiddly, up quite high in the footwell, and I recommend using a strap-on forehead light. Even then you won't be able to see exactly where the hole is. I have included a couple of pictures I was able to grab by sticking my camera up behind the dash which may give you an idea. You have to do it by feel alone, but a little light in the footwell is reassuring to show you might be in the correct general vicinity! You might also check-out a few diagrams on
eper/pekidi, and perhaps find some pics of used pedalboxes on ebay ! By the way, if you ever do try to buy a used pedalbox do check the pictures very carefully. At least two I found recently had the brake light switch mounting hole already broken out as described - probably by some inadvertent yanking out and separate sale of the switch!
Anyway, back to the job at hand. It is just about possible to twist unlock your switch, or twist engage it, with one hand. My hands are big but luckily I have long fingers. However, never force it, just be patient and reposition it or yourself slightly and try again. If you get it into the exactly correct start position it will rotate and click in position quite easily. If not quite in position or slightly out of line it can be remarkably obstinate! The switch goes into place in the direction of the red arrow in the pic below i.e. from the front of the car with switch plunger headed towards the back i.e. towards that lever which is an extension at the top of the pedal. If that lever is allowed to go too far forward (which it can't normally do unless forced, or if the pedal is part disconnected and yanked upward) then that lever extension can easily cause damage by punching back the plunger and switch right the way through an inadvertently enlarged hole!
Here are a couple more pics showing the actual switch is place:
The first pic shows the plunger touching or almost touching the lever at the top of the pedal. The pedal is not depressed. In the second picture, the pedal is depressed and there is a gap between the pedal lever and plunger, but the plunger seems not to extend very far nor move much (if at all) between the first and second position.
The problem here for me was that in both pics, the brake lights were on when the ignition was turned on. That means that either the plunger was not touching in pic 1, or even if it was, it was certainly not depressed enough to break the electrical contact inside the switch. Remember, lights supposed to be off when brake pedal isn't being used and that means that the top part of the brake pedal ought to be pressing on the switch when the bottom end of the pedal has no size 12 pressing on it. But is that the situation here? It seems not ...
So what's inside the switch and could I get the plunger to spring out further and calibrate it somehow so it works as advertised? The answer seems to have been yes I could (because I did!)
I opened the switch very carefully by using the edge of a thin sharp knife. The switch is not glued - it is a clever click fit, but as it is all plastic and is closed against a spring, you need to tease open the six click nipples without breaking anything otherwise you'll never get it to close properly afterwards.
Here are some pics of how I teased it open:
Careful not to let it all pop open or lose the spring before you can see how it all fits together. It isn't overly complicated but it is always best to keep the parts in the right order in respect to one another!
Here is a pic of the main parts separated and one of the plunger showing a kind of saw tooth ratchet:
That ratchet reveals part of the secret of how the plunger can be calibrated according to the actual gap it finds between it and the pedal lever extension when you are fitting it from new or refitting it after dismantling as I have done. That black collar around the plunger (adjacent to the white section in the switch) contains another part of the secret. The collar has guide rail prongs or splines that match some grooves inside another black part left within the blue housing. Suffice to say that the part inside the blue housing rotates 30 degrees and two lugs on it protrude outside the housing to provide´the "click" when the switch engages into position after twisting. And evidently part of that locking process also rotates the splined collar which in turn engages and locks along the ratchet teeth on the plunger!
This now gives some meaning to the advice I have read in another thread somewhere that before refitting the switch, you make sure you hold the brake pedal depressed as far as possible. That way when you first offer the plunger through the hole, and if you have extended it out a bit (or a lot!) from where you found it before dismantling, it will not get pressed back in too far by the pedal lever. If you forget to depress the pedal until after the switch is rotated and clicked in position, the plunger will probably be locked too short, and you might well end up with brake lights on all the time. The idea if you have held the brake pedal down when you rotate the switch 30 degrees to lock it in position, is that the ratcheted plunger will also be locked in a supposedly perfectly calibrated position. That means it will just touch the top pedal lever extension part when the pedal is depressed, and when the pedal is allowed up, there will be definite depression in the plunger of what I estimate to be around 5mm or so, where when I started I seemed to have no noticeable movement until I took the switch out of position and pressed in what little remained of the protruding plunger with my finger.
One further hint tonight: Which way up does the switch start off when you first offer it to the hole? Well take a look at my first pic of the whole switch again above. To me it looks like the rough shape of an old style in-line engine and gearbox with the plunger looking like the propshaft stub. The engine is taller than the gearbox. Keep it very approximately that way up* and reverse the propshaft/plunger through the hole in the pedalbox, i.e. insert from the front of the car to the back. Then, imagining you are at the front of your car rather than struggling in the footwell, you will now try to rotate the whole switch anti-clockwise in the hole so it clicks and locks - all the time holding down the brake pedal as best you can!
* I say approximately that way up, but it does start perhaps 5 degrees past vertical in the clockwise direction as described from the front of the car, and when you twist lock it anti-clockwise you pass through vertical. As I say, this is all done by feel and practice makes perfect although I don't know how many times you could fit and refit one of these without the plastic around the pedal box hole getting fatigued and giving up!!
Apologies for a long post - I just hope this helps someone! If anyone wants to ask about the clutch pedal switch and what I have experienced there, then we'll save that for another post I think ;-)
NB For avoidance of doubt, my Evo is LH drive, and that may mean fitting and refitting the switch is tougher for me than for UK RH drive models which whilst the switch may be in the same rough location (left footwell) I think it is mounted on some right footwell to left (passenger) footwell mechanical linkage, but of course without the clutter of the pedalbox itself which of course is in the RH footwell in UK!
PS Whilst I had the switch dismantled, I roughed up the contacts inside it with a small screwdriver for good measure - not sure if I did right, but it all seems to have worked!
