Chevrolet Repair: No Brake lights, chmsl, bed cap

Question
I have a 1997 Chevy CK 1500 4x4 with a center high mount stop light in the truck cap. The right turn signal works fine, both inside and out, front and rear. The left turn signals blinks both front and rear along with the CHMSL but the left turn indicator doesn't blink inside. The brake lights never work. With the brake applied, all of the lights work as described above just the same as when the brake is not applied. Thank-you

Answer
I'm assuming the CHMSL is mounted on an aftermarket bed cap and is most likely wired wrong. It sounds like it was just wired into the left brake lamp wiring.

I'd start by checking all the fuses.
Then if still not working you'll need to trace down the brake light circuit.

I have replaced several defective brake lamp switches on this type of vehicle in the past...the switch may be defective.