240 Brake Failure Light - Servicing Sydney?

Just did a replacement of my brake pads on my 1979 Volvo 244;

The calipers aren't in the best shape, and the rubbers on the pistons are shoddy, but they still function fine. I slowly set the brakes pads in over the following 100k (thereabout), no crazy braking etc.

Now my brake failure light has come on... slight flicker at full compression, but there for good.

I'm guessing it might be gunk in the line or similar? Anyone have advise on how to reset the sensor? -Failing that a good volvo mechanic in Sydney? (Normally I do everything myself, and had a bad run at Savvas years ago)


Thanks in advance!!

Comments

  • I thought when the brake light is on means low in fluid. If fluid is fine check the sensor. I would also bleed all brakes back left right front left right in that order.

  • Lupica motors in morebank

    Joe (owns the shop and loves 240's) would easily take care of it right the first time

  • PoppyPoppy (@Poppy) Sydney, NSW

    Thanks guys, I might try Lupica. I think bleeding is the first step, but I've not done it before...

  • carnut222Greg S (@carnut222) Daylesford VIC

    Definitely bleed the brakes/flush out old fluid. In your 79, there is no brake fluid level sensor (that only came in the late 240s). Your brake light is activated if the pressure in one circuit is lower than the other circuit...the distribution block on the passenger side chassis rail contains a piston that moves one way or the other in this condition, earthing a contact switch and turning on the warning light...the block can get corroded internally which means even after the pressure is equalised the sensing piston doesn't re-centralise. Sometimes the electrical switch can also prevent re-centralisation of the piston. Try removing the switch if after bleeding the brakes the light doesn't go off.

  • jamesincJames (@jamesinc) Oz Volvo Ice Fortress

    Sometimes after doing pads or flushing brakes I end up with the failure light on, I just crack one of the lines off the master cyl with a rag under it and have someone very slowly press the pedal to change the balance. If the light hasn't gone out by the time their foot is half way down, I nip it back up, have them pump the pedal, then crack the other line and repeat, and they just yell out when the light is extinguished.

  • carnut222Greg S (@carnut222) Daylesford VIC

    Good suggestion James...probably what that’s doing is forcing the piston back towards the centre. Technically it should self-centre, but I suppose they get gunk and corrosion in them so you’re just helping it along! :)

  • jamesincJames (@jamesinc) Oz Volvo Ice Fortress

    Yeah exactly, and letting the human calibrate it :)

    I've found they do usually self-centre eventually but they take ages to get there, like weeks. And this has been true even on Nina's car where I tore down the whole brake system and cleaned everything, including the distribution block.

  • Ya'll doing it the hard way. Assuming everything is in fact balanced and the piston is just sticky, its easy to reset. Just unscrew the plug the wire goes to then stick a flat head screw driver in. Gently lever the piston shown in the diagram below till its back to its normal position. I have done it before with success.


    Ex850R
  • jamesincJames (@jamesinc) Oz Volvo Ice Fortress

    @VolvoHordz my way is easier! We need to have a race

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