CK5
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2003 duramax no brake lights

The two wires on the left are for the brake lights. Orange is power coming from the fuse (hot all the time) and the farthest left is white and that is output from the brake switch. If you can get a test light in there you can just probe them from the back on that style terminal.
I have a test light. Does the ignition need to be on to test?
 
no the brakes are hot at all times, If the orange wire does not light the test light turn key on, prove orange is hot. then switch test lamp to white wire push pedal, light should light. if not switch is bad, or your ground for test light isn't good.
 
no the brakes are hot at all times, If the orange wire does not light the test light turn key on, prove orange is hot. then switch test lamp to white wire push pedal, light should light. if not switch is bad, or your ground for test light isn't good.
Orange: lights up
White: lights up when pedal is pressed.
Brake lights work when pressed and work with trailer brake hooked up and disconnected.
 
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Those brake switches can be very intermittent. The problem will most likely come back.

To remove it, iirc, you remove a clip from the brake pushrod and then kinda rotate the switch around and off of the pin. It's not hard to do, but definitely not fun either.

Also, there are two versions of that switch. They are essentially identical, but opposite of each other. One has an all-white casing, the other has a white and black casing. Make sure the parts store gives you the right one.
 
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