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  On my 1977280, the emergency/parking brake switch has only one wire.  Black w/ male lead from bottom of switch to ground. The FSM shows this B wire from switch to ground yet also a green/yellow stripe wire going toward the switch..does this GY (ignition powered) energize the switch?  How does switch energize for the black wire to function as a ground?

Edited by Packerz
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Anybody? Doesn't the switch need to be energized someway (wire connection??) so the existing black lead functions as ground? 

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Yes, it does.  Is there a problem?  Not really clear why there's a question, no offense.

Edit - looks like there's a fuse...

77 brake warning lamp.PNG

Edited by Zed Head
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Alright!  The GY wire does energize the switch and your illustration very clearly shows a factory GY lead out from the switch itself.  My switch is missing this outgoing wire ...this would identify what my existing GY wire (coming from C6) with a female plug was once connected to.  Thank you for this diagram!!!  My '77 FSM didn't show clear detail of switch connection, the yours does!

One last question, please: could you direct me to an OEM or aftermarket source for a switch with this GY "pigtail"?  

Zed Head, Thank you again for your help!    Doug

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It's not really a "pig tail", it's a length of wire that comes from the connector by the fuse box.  It could either run down the door under the carpet and across to the switch, or across the dash and through the console to the switch.  But it will be just a wire in a bundle of other wires.  C-6 is in the junction block by the fuse panel.

Here's a link to the factory FSM.  Body Electrical chapter, Meters and Gauges has the diagrams.  http://www.classiczcars.com/files/category/13-280z/

rest of the story 77.PNG

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Again, thank you!  

Zed Head, could it be that this black wire, soldered to bottom of the switch, is not a ground wire at all... It might actually be the switch connection to the 12 volt power GY wire.  This could explain my male spade black wire and my female plug GY making them the same wire when connected and bringing power to the white plunger button sleeve   Then the sleeve is in fact grounded by the switch housing which itself is grounded as part of ebrake assembly bolted to body ground.  Do you think maybe I've (finally) got this right? I sure hope so!  I really appreciate your excellent feedback and patience with my questions!!!    Doug

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I think that you might be right.  I just went and looked at my 76 and I can see the GY wire coming from what looks like under the passenger seat and connecting to a black wire via a bullet connector.

The way to test the black wire would be with a meter or a continuity checker.  You'll get continuity to ground when the lever is up, and the circuit will open when the lever is down.  That would show that it's a path to ground controlled by the lever position,which is how the system functions.

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Yippee and way cool😎  Ya know I would have sworn a black wire was ground... not on a Z anyhow😏.

Do you possibly have an aftermarket LED bulb part# suggestion/source to match the dimensions of the current (5amp?) dome light bulb. Can an installed bulb be tested by using just the lens push switch if only the Blue w/white stripe (12volt power) and the Black (yeah black=ground this time) are connected to their terminals inside the light housing? or does the Black w/red stripe (from door switches) also have to be connected to its terminal for any bulb to work at all?  Last two electrical questions and end of this thread; I swear!  You are great, my friend.  Thank you.

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No problem, I learned something about my own parking brake.  A good puzzle.

Check that Body Electrical chapter for the dome light circuit.  Pretty sure I flipped by it on the way to the parking brake light page.  I think that it might be similar to the e-brake with several possible ground circuits.  You can push the door button with your finger though, easy check.

Start a new thread for LED's.  There are some guys here who know quite a bit about them.  I don't know much.

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