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Technical 700R4 Brake Light switch

Discussion in 'The Hokey Ass Message Board' started by deeppurple52, Nov 23, 2016.

  1. I have a 1991 gen III K case 700r4.... no pressure ports on the passenger side. The most common recommendation is to run 12v power from the brake light switch. Okay, no problem. My switch is a normally open pressure switch in line from the master cylinder. Wiring to the hot side of the switch will give me 12 volts all the time.... good. Stepping on the brake pedal changes nothing, still get +12v. There is nothing in my setup that will drop out power with the brake pedal unless I go thru a relay. Again, no problem. It appears to me that an easier solution is to just run switch power thru a switch. What say you?
     
  2. squirrel
    Joined: Sep 23, 2004
    Posts: 46,694

    squirrel
    Member

    you're trying to wire up the torque converter lockup? I'd just run ignition power to a pressure switch on the VB that gets pressure when it goes into 4th.....then to the solenoid.
     
  3. gimpyshotrods
    Joined: May 20, 2009
    Posts: 17,480

    gimpyshotrods
    ALLIANCE MEMBER

    You need a different switch.

    There are GM style brake light switches that have two sets of contacts, instead of one.

    On a conventional switch, pushing the pedal down allows the contacts to close, and the brake lights come on.
    [​IMG]

    On the double switch, that still happens, but there are a second set of contacts that open, cutting the current to the lockup circuit.
    [​IMG]
    or
    [​IMG]
    AC Delco D862C
     
  4. squirrel
    Joined: Sep 23, 2004
    Posts: 46,694

    squirrel
    Member

    the dual type switches were used on GMs with cruise for many years, too...
     

  5. Perfect! Exactly what I was looking for. Thank you.
     
  6. gimpyshotrods
    Joined: May 20, 2009
    Posts: 17,480

    gimpyshotrods
    ALLIANCE MEMBER

    That's what I'm here for!
     
    pat59 likes this.

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