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Discussion Starter · #1 ·
Hi all,

Anyone know off hand how the instrument cluster brake lamp wiring is done? Clearly I've studied the wiring diagram in the manual, but I'm using a 1968 ignition switch (in a 67), and my cluster had been wired by scratch (by myself.. ages ago), and I just ripped out a universal harness.. So I'm starting from scratch again.

Going by the diagram for a 68, it looks like...

Wire 640 (Red/Yellow) is going to one side of the bulb.. From the ammeter (no longer have)?
The other side, 997 doesn't even have a Color call out in the diagram.

(Attached the diagram I'm looking at for the cluster)

From what I remember, this Brake Light in the cluster has something to do with the black -ve wire in the ignition switch (Which I wasn't using). Prove-Out?

So normally I would assume there is +ve going to the brake switch (in the MC), and that goes to one side of the bulb, and the other side gets grounded to the ignition switch.

but that wouldn't work since the dash light still wouldn't illuminate as the Ignition on Test without having the Brake Light switch (on the MC) closed. Soo..

Anyone wired one of these Dash Warning lamps up from scratch?

Thanks!
 

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Discussion Starter · #4 ·
Thanks! (67/68, doesn't matter to me, I'm using a 95 MC so switch will be two wires, one going to ground)..

So judging by what I read in your thread:
Bulb has +ve going to one side of it.
The other side of the bulb goes to the terminal on the Ignition switch (Which I'm currently not using in the old build).
That wire, from the ignition switch, then goes to the MC switch (which in my case, or 68, then has a wire going to ground).

Obviously, when brake failure happens and that switch closes, +ve bulb gets ground, light up dash Lamp.

But also, when in Crank, Ignition switch grounds that wire, also igniting the dash Lamp (on SOME switches. And repros don't work correctly is what I'm reading)?

Sound about right?

(Currently, on my old harness,I just have 1 side of the switch going to ground, then into the car, to that lamp, then +ve. Works fine, but doesn't "Test" when the car is started.
Wondering if I want to mess with that whole circuit just for a Test Lamp function. And that's the only function of that Black wire on the ignition switch (Been working fine without it for 10 years on mine. hah)
 

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The switches can be swapped. But yes, it sounds like you have it worked out.
It works on my 67, but just before the crank position.
 
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