brake light on

[shenab]

Hello colleagues

typical this, after a tech day an all. Driving in the snow this morning and my brake light comes on solid. Pulled over and let the car settle, did the usual with hand brake etc but still on.

Brakes seem of if a bit sensitive. I figured that was an indication of low brake fluid but it's sitting 2-3 mil over the min line.

Any thoughts, bearing in mind I'm not a tech and would just like to sound intelligent when i bring it into a garage later.

BTW it's not freezing here ..

thanks peeps
Shenab

[mx5ash]

My guess would be a the switch is getting stuck. I assume you are talking about the handbrake light (!) on the dash.
If you could get a look at the handbrake handle you should see a little micro switch. Try to free that up and spray a little wd40 or similar on it.
Hth Ash

[shenab]

Turns out it was the fluid .. if I had opened the thing I would have seen it! Sensor was dry.. so much for not over filling. All good to go now ..

thanks Ash and Steve!

[sidewaysreilly]

eh, if your light comes on, your pads are probably well worn. Unless your fluid is leaking. Its a closed system so fluid level goes down as the pads wear. Light goes on to warn of this or a fluid leak. get your pads checked asap.

[TeenaG]

If the brake fluid is low... the big question is... where's it going? Check calipers for damp spots.

[franksm]

Could jus be that, as SWR implies, our Shena likes to use the brakes and has worn the pads down. The fluid level drops as a consequence. Put new pads in, the level comes back up.

Or there could be a leak, but that's easily detected (drips on the wheels or ground, and a soft foot pedal)

[shenab]

"Our Shena" is actually quite light on the brakes, preferring to use my gears instead as God intended. Ask anyone who drives behind me on a run

The fluid wasn't that low only just below the sensor actually so I suspect this is normal as I don't think I've ever had to top it up in the 3 years I've had it. I only had to put a couple of mil in to top it off and the light hasn't come on since.

Even in a closed system you are going to get burn off and some fluid will be depleted surely? Or (as Will would say) am I on crack?

I have a mate giving it a once over prior to the big road trip in May so will ask him to check out the pads then.

Thanks for the suggestions peeps

S

[sidewaysreilly]

not really as brake fluid is hygroscopic......it attracts water and so the need to change it every few years.

[shenab]

so the theory being then it would only expand rather than burn off?

[Steve]

yeah kind of, but the water in the fluid won't perceptibly affect the fluid level.

[franksm]

It's an hour's work to change the fluid, I'll give you a hand with it some day if you like.

I bought a machine that sucks the old fluid out under vacuum, so the hardest part theoretically is getting the car onto jack stands and taking the wheels off

[shenab]

Frank - thanks a mil for the offer. I'll get my mate to do the hard work if it needs it during its once over.

So what we are saying is if the fluid drops enough for the light to come on there is definitely problems with the brakes??? Even if topping it off slightly fixes the light coming on issue?

S

[franksm]

No, I don't think you have trouble unless your brake pedal feels spongy or unless you have drips around the wheels or master cylinder.

But brake fluid 'goes off' what with all the work it does - boiling and absorbing water and dirt, so that's the only real reason it needs changed every few years.

Your level most likely dropped because the brake pads wore down, and the pistons in the calipers had to extend out to compensate - so there's more room for fluid in the system, which is why the level appears to drop. With new pads in, the pistons only have to extend out a few millimetres; old pads may need to pistons to be extended out by 10 or 12mm each, which when you add it up, shows as a similar drop at the resevoir

If you did have a leak somewhere, your brake pedal would be halfway to the floor, it would be totally noticeable.

[sidewaysreilly]

well putted there frank.