Brake warning light on (again)

Discussion in 'Mech Tech' started by Zebedee, Nov 27, 2011.

  1. Can i add my thoughts to this one. My bus is fitted with this light (US spec. ). I have a switch on the handbrake lever which puts the light on. It looks the same as a door pin switch. This may help. ;)
  4. I tried disconnecting the '61' wire at the alternator end (with the engine off) and the light stayed on. It made the alternator light dim but not go out totally so i assume theres a wiring gremlin somewhere.
  5. Removed the stereo again and didn't find any trapped wires and no loose ones either. I did finally manage to get to the wiring on the back of the warning light and with a multimeter I get:
    12V at 15 terminal (wire from fusebox) with ign on
    12V at 61 terminal (wire from alternator/ign waring light) with engine running
    but i still get 1.15V at 61 terminal with just ign on ???
    0V at K terminal (red wire from brake light switches) with ign on
    and 0.35V at K terminal with ign on when brakes are pressed.

    I don't reckon there should be any power at the K terminal at all if the brakes are in good condition and i'm not sure about the 61 terminal though i suspect that shouldn't have any power with just the ign on either. :-
  6. Have you tried bleeding the brakes just to be sure it's not a fault there rather than the electrics?
  7. Not managed to get any new brake fluid so not done that yet.
  8. Must have just been a duff warning light as thanks to the replacement i got off Majorhangover i now have a working brake warning light. :)
  9. My dad disassembled the old broken warning light and found a burnt out transistor. Replacements are pennies so he's gonna see if they are still available and solder a new one in so i can keep it as a spare.

    He did the same thing on my eberspachers control unit. Over £100 from espar for a second hand control unit or under £2 for all the transistors on the whole circuit board. Guess which option we chose? :p
  11. Its apparently got a switching transistor in it which wasn't anymore.

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