brake switch wiring question (1 Viewer)

[Mightymes]

Hey everyone,
I have a questions about brake switch wiring. I have an 5.3 swap in my 40 and the wiring harness I have with the engine has a purple wire that says: Purple, brake switch - supply 12V to this wire while the brake pedal is NOT PRESSED. When the pedal is pressed down, the 12V signal needs to stop, creating an open circuit. This is used by the ECM to disengage the torque converter lock-up.
I have a brake switch with 4 wires on it. 2 that are red/white and two that are green/white. Would I hook that purple wire up to one of the green/white wires? If so, does it matter which one? Or, does it go to the red/white ones?
thanx
Craig

 

[reddingcruiser]

I added a separate micro-switch to accomplish this that contacts the pedal. The OEM brake light switch is normally open. You need a normally closed switch.

 

[Engineer8000]

This is the typical brake light switch arrangement. If I recall correctly, when you push the brake pedal the switches close, the green wire switch operates the brake lights and the red wire switch operates the brake warning light if the pressure switches at the master cylinder do not detect pressure. You cannot get the signal you need from this. You could use an auxiliary relay that operates off the break light or a separate switch operated by the brake pedal.

 

[Mightymes]

Would something like this work: Painless Wiring
Here is the diagram for it: https://www.painlessperformance.com/Manuals/80176.pdf
What I'm not sure about is the ignition switch fused???

 

[reddingcruiser]

Seriously, this will do the job. It's a 15 amp micro-switch you can get from Grainger, McMaster-Carr, etc. All you are trying to do is interrupt the 12v power source through the purple wire to unlock the torque convertor so the trans doesn't try to drag you through an intersection when you come to a stop.

 

[reddingcruiser]

You need power when the key is 'ON', (or in the RUN position).

 

[reddingcruiser]

For Reference:

 

[Mightymes]

For Reference:View attachment 2176929

Do you have any pics of how you mounted it by any chance?

 

[reddingcruiser]

I can get you one in a bit.

 

[Mightymes]

ok, thanx

 

[reddingcruiser]

Hard to get a good picture looking up under the dash, and my modified brake pedal arm may throw you off, but you can see the bracket holding the switch and how the switch makes contact. It's adjustable and mine is set to open with only the slightest travel.

Directly behind the purple wire you can see the OEM brake light switch.

 

[reddingcruiser]

The switch bracket itself is attached to the left side steering column mounting bolt on the bottom of the dash

 

[Mightymes]

Is the purple wire the only wire hooked up to the micro switch?

 

[Mightymes]

The switch bracket itself is attached to the left side steering column mounting bolt on the bottom of the dash

I'm looking at Mcmaster Carr and they have a few of them. Do you remember the model number to the one you're using?

 

[reddingcruiser]

I have a trail spare I can dig out tomorrow.

 

[Mightymes]

Great, thanx!

 

[reddingcruiser]

@Mightymes, I didn't forget about you, just been under the weather for the past several days.

 

[Mightymes]

No worries, no big hurry.