67 Dart Brake Lights

Discussion in 'Electrical and Ignition' started by pghjeeper, Nov 7, 2018 at 10:06 AM.

  1. pghjeeper

    pghjeeper Active Member

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    Hey gents I have a question, so I just picked my first a body, a 1967 Dart GT. She is clean bodied California car, but she has some small issue.
    The rear brake lights are stuck on and the gas gauge isn’t working. Now from reading I know the brake light switches can be an issue. But my buddy, who knows a hell of a lot more than me about Mopars, seems to think it’s a ground issue. I have to add that even though my interior is like new I do smell what I think is mouse inside the interior. I’m gonna yank the back seat this week and check out the brake light switch. What else could it be? Should I just replace the rear harness?
     
  2. el5dart

    el5dart Well-Known Member

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    mice seem to like the headliners. look behind the visors for a little hole.
     
  3. pghjeeper

    pghjeeper Active Member

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    I’ll do that but I think the headliner is new
     
  4. HemiSSDart

    HemiSSDart Dartus Interuptus

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    The brake light switch attached to the brake pedal is probably bent, it has a thin sheet metal bracket that can get bent easily. The gas gauge might be the ground strap like this one, they usually rust out or come off:

    Mopar Gas / Fuel Tank Sending Unit Ground Strap | eBay
     
  5. Garry in AZ

    Garry in AZ Building a 9 second Valiant FABO Gold Member

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    I don't think the brake lights on all the time is a ground problem, since the brake light switch in your car sends positive 12V to the bulbs. Likely a misadjusted, sticking, or defective switch.
     
  6. RedFish

    RedFish Well-Known Member

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    The only ground required is at the bulb sockets so if they come on ground is not the issue. Brake pedal should return to push the switch button. That opens its contacts, lamps go off.
    The only return spring is inside the master cylinder. That should be a constant, yet we've seen cases where the pedal arm doesn't align with the switch button. Switch bracket bent? The pedals pivot points worn? Firewall distorted at the master cylinder? Who knows?
    Hopefully you can push the button with a finger and the lamps will go off. From there its a matter of adjustment. A single small screw ( 1/4" hex head? ) attaches the switch bracket. Loosen that to adjust switch position up/down. You would have to bend something for left/right adjustment.
    Good luck finding that mouse too.
     
  7. Dana67Dart

    Dana67Dart Most undignified way to get to Colorado!

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    regarding brakes on all the time...

    not a grounding issue if they are on all the time. the bulb is grounded at the bulb and the power is supplied via the brake light switch
    upload_2018-11-7_10-16-41.png


    1. if you lift up on the brake pedal do they go out? IE pull the brake pedal up and toward the rear of the vehicle.
    if so it is an adjustment issue.

    2. if not disconnect the connector from the brake switch, do they go out?
    if so bad switch or switch is stuck closed.

    download the factory service manual from MyMopar.com it has a wiring diagram and will be very helpful.


    Regarding fuel gauge...

    1. Does the temp gauge work?
    if so the instrument cluster voltage regulator (IRV) is working.
    if not the IRV may be missing or bad

    1a. with the key on check for a voltage ~5-6V on the back of the fuel gauge screws.
    if no voltage then the gauge circuit board is may be bad
    if there is voltage continue

    2. find the connector that goes to the fuel sending unit, single connector on sender. with key on and someone watching the gauge short the single connector to a known good ground for a few seconds.
    If the gauge starts to rise it is a sender or sender ground issue.
    If it does not move then it could be a broken / disconnected wire between the sender and gauge.

    3. with the key off and the sender wire grounded check for a ground on the back of the fuel gauge screws.
    if no ground then it could be a broken / disconnected wire between the sender and gauge.
    if there is a ground then the gauge is bad or there is no voltage to the gauge

    If you have a bad sender and it is the OE sender DO NOT toss it. look to have it rebuilt. even if it is more expensive you will be MUCH happier with the results. Aftermarket senders are not very compatible
     
  8. pghjeeper

    pghjeeper Active Member

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    I’m going to have the car home tomorrow. It’s still sitting at my buddies garage so I will know more and post up.
    You guys really are a great asset thanks
     
  9. pghjeeper

    pghjeeper Active Member

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    Ok gents the Temp and Fuel gauge are not working. The rest work fine. I have no turn signals, you can feel the cam inside the column is not working right as the arms doesn’t lock in place. I also have no hazards.
    The brake light was just the switch, I was able to push it in and shut the lights off.
    On a bonus note the trunk is amazing!! The spare tire wheel looks brand new. Only rust is surface rust from the Vinyl liner. Plus it was loaded with a bunch of spare 340 parts that I have no use for.
     
  10. RedFish

    RedFish Well-Known Member

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    Since both gauges are inop, the most likely culprit is instrument voltage regulator/IVR.
    Find the purple wire at temp sender, check it for a pulsing voltage at switch on. If it doesn't get pulsing voltage the fuel sender circuit probably doesn't either.
    The IVR is a small metal box like component plugged into the back of the inst' panel.
     
  11. pghjeeper

    pghjeeper Active Member

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    Will do, I have read that the early Darts,
    Not sure if 1967 is one of them has the IVR built into the temp gauge is that true?
     
  12. RedFish

    RedFish Well-Known Member

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    Yours is plugged into the back of the panel. Some very earlier models had the IVR in the temp gauge. Then later on it was moved to the fuel gauge for some models.
    The plug in type is standard, most common.
     
  13. pghjeeper

    pghjeeper Active Member

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    Does anyone have a picture of it’s location until my Service Manual shows up.
     
  14. 67Dart273

    67Dart273 Well-Known Member

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    You can download a service manual, free, at MyMopar. Also the PC board on the cluster as well as the studs/ nuts for the gauges can be a problem. You might want to read through this thread:

    Printed circuit pins repair

    My 67 had several cluster problems:

    1...A bad IVR so I bought an aftermarket solid state one
    2...Several of the PC board harness pins were broken or loose
    3...The IVR socket contacts were not making reliable contact with the board traces
    4...At least one of the gauge studs the nuts were loose/ corroded.