Technical Discussion Thread: Brake Light Switch Replacement

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Technical Discussion Thread: Brake Light Switch Replacement

Deckchair5

Whaddya mean too old?
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Yep, you read it right, not brake light problems but solutions to a problem you didn’t know you had. Many Stilo owners will have had to change their brake light switch through ASR warning lights and brake lights not working or staying on sort of problems but for those that haven’t then I feel you should be forewarned of something that may be coming your way if it hasn’t already.

Imagine the scene, I’m driving along a dual carriageway and a young lass draws up along side and is pointing and mouthing intelligibly something like “I thought my bum looked big until I saw the back end of your Stilo”. At least I think that’s what she says and so I smile sweetly, give her a thumbs up and say back something which probably looks like “Yes you can get a full wax, back and crack down the road for £45 don’t you know”

Anyway, I decide to check things at the rear when I get home and I’m lucky in being able to check my rear lights in a neighbours front window acting like a mirror -spoils his TV viewing but handy for me. So everything looks intact and I check my brake lights a few times in the window –
Fine, fine, fine, fine, fine, uh?
Did I imagine that? Did the high level brake light come on but not the low level ones? Is that possible?
Fine, fine, fine, fine, then same again!
Fine, fine, fine then NOTHING! What’s going on?

Looking at the circuit diagram the high level brake light is indeed on a different circuit to the low level ones, the high one being directly connected to the brake light switch and the low level ones only being turned on by the body computer so it’s easily possible for the high level to work with no low level ones

Now I hear that new brake light switches are better designed and more robust than the originals, the operating point isn’t right at the top and therefore over sensitive and the switch isn’t so affected if you happen to trip your foot underneath the brake pedal. (The original would often reset it’s brake light operating point just by a simple act of pulling up on the brake pedal or catching your foot underneath it. Not good).

So I’d advise everybody to check out the operation of their brake lights, not by asking someone to check as you won’t know what’s happening, but by reflections and watching what happens with your own foot operating the brake pedal. If you’re getting odd things happening too then it’s time to replace the brake light switch before someone reshapes your rear end

New switches are £5 from Fiat. Not too difficult to fit but I’d advise practising shuffling a deck of cards with one hand in the dark upside down first

HOW TO REPLACE
Remove the sound deadening over foot panel and throw it away if you haven’t already done so, more room for your feet and you can hear the indicators as well then.
Switch is a bayonet, light bulb type, half turn to remove. Connector to it is a pull up release catch which is where you’ll need the fingers of steel and origami in the dark skills

Refitting is absolutely nothing like removal (just like it should truthfully say in the Haynes manuals) as you will be all out of patience and fed up with being upside down by then

Don’t forget to test the operation afterwards
 
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Re: Brake light solutions

So I presume this happened to you then Decks?

Are you saying that you need to keep pressing the brake peddle half-a-dozen times or so to be sure when testing rather than relying on a single press?
 
Re: Brake light solutions

Both our Stilo's have had this replaced, Mum's due to brake lights sticking, mine causing repeated ESP errors. And this can also cause the Selespeed models to not start as the car won't know the brake pedal is depressed or throw a general error.

This is a sticky for now . . . until something is done about the "Stilo Common Fix" section.
 
Re: Brake Light Switch: ESP/Lights/Selespeed Problems?

Ok, I definately have this problem now, and the reflection of the brake light is either none present (which is dangerous) or its really weak. I paid a visit to Fiat Glyn Hopkin Loughton yesterday and went to the parts department to pick up a brake light switch. They sold me this.

DSC02435.jpg


Im ready to set to work to eradicate this problem once and for all.

Deckchair, how easy is this thing to fit once I take off the sound deadening thing. Do you have some good step by step directions on how to get rid of the old and fit the new.

This would be very much appreciated as usual(y)

Thanks
 
Re: Brake Light Switch: ESP/Lights/Selespeed Problems?

It's fiddly and requires some good control one handed under the dash. Get the driver's seat as far back as it will go. The switch is right above the brake pedal arm and, at first, looks like a right pig to do as you can only just get your fingers on it and have to go almost toally by feel but, like a light bulb, just a half twist of the switch and it's out, push it upwards to release it from it's securing bracket. i did it so many times i can do it in seconds now so it's not difficult but a bit of a strain to get to so get comfy

Once it's released you have a bit of slack in the wiring so you can move the switch over the top for a bit more slack so you can get to the electrical connector. This is just a raise release catch on the side of the connector and pull off, again tricky because yoi could only use one hand on it but, once the connector is off, the switch is out

You reminded me though that I had a problem fitting the new switch as it just would not rotate to lock into position no matter how hard i tried. I needed to file off a small amount of the plastic from here on the locating lugs of the switch to enable it to fit.

DSC02435.jpg

The plastic moulding lugs had some overhanging plastic preventing the switch rotating in to secure it. You might have this too. That was frustrating as it could have gone in first time and took a while to realise why the new one just wouldn't go in but the old one would go straight in

Once installed, remember to adjust the centre plunger as described above. You can check the operation either by reflections or by raising your tailgate as you can then see the high level light whilst you put your foot on the brake
 
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Re: Brake Light Switch: ESP/Lights/Selespeed Problems?

Just replaced it, the old brake switch was not connecting to it properly, took a few hours as I have little to none experience with these things, but cant fault deckchairs help, I will now probably be able to do this again without heading to the dealers. For anyone needing assistance for this problem, follow this guide and simple, you cant go wrong(y)
 
I don't understand what you mean T1
I would think you'd end up with your brake lights twitching on over bumps or even permanently on if you set the switch artifically high as its a hyper sensitive switch. How will harsh braking affect the switch trigger position?
 
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Thanks for the info,

Came back from holiday and had the same problem, had a rear stop lamp out.

Replaced it but then noticed that the brake lights were on all the time unless the brake pedal is 100% all the way to the top. Tried to reset the switch but think the switch is dead as did not work (Worked for one depression that was it).

Will buy and new one from Fiat and see if that does the trick....
 
Originally Posted by Deckchair5
I don't understand what you mean T1
I would think you'd end up with your brake lights twitching on over bumps or even permanently on if you set the switch artifically high

T10486 "Thats exactly what it stops".

How can it do that? Look at this
View attachment BKLT1.BMP
As you know, to set the brake light switch correctly you pull the switch centre plunger out and then allow the brake pedal to rise on its own without pulling it up.

View attachment BKLT.BMP
If you pull the pedal up (or get your foot stuck under the pedal) the switch gets set too high and you get brake lights jittering on over bumps or even have them permamently on
View attachment BKLT2.BMP
The same thing will happen if you put a feeler gauge between the pedal and the switch plunger when you're setting it

I can't understand what you mean when you say "Use a 1mm (increase to 2mm if required) feeler guage between pedal stop & switch plunger when settiing up,this prevents having to reset under hard braking"
Can you explain what you mean and why hard braking would make any difference as I can't understand the logic here?
 
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Lo all,
I had this exact same problem with my uno. The switch looks identical and is simple to replace.
Although I would like to see a circuit diagram as I am a cheapskate and would rather fix it than replace it.
I opened the switch and found it was dirty, so I cleaned it and replaced the spring but had no luck.
It looks to me like it should be a normally closed circuit, and when the brake is pressed, it opens. But that would mean it goes to a relay. UNless it is a relay in itself? why then do the lights come on when you touch the wires together?

I dunno. I will get it eventually. an easy way to check for this is to pull the wires out (gently now, don'trip it apart) and touch them together. If the lights come on, replace the switch. if not you have other problems.
 
There's a lot more room under the dash in a Uno, it's not quite so simple in the Stilo as you can't see what you're doing:)

There's no internal circuit or relays to the switch, it's as simple a switch as you can get. It's normally closed (when you press the brake pedal it takes the pressure off the switch) which is why the brake lights work if you connected the two wires together. That's not a duff switch, that's the way it should be
 
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My Stilo has now developed this problem, or should i say i've just noticed it!!
No brake lights at all at times, it seems intermittant though, all or nothing,

Not sure about the 3rd rear screen light. Decks, can you confirm this should work regardless?

off to fiat then..........
 
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