Packard Forum Index » Post-War (1946-54)

Hello I have a 51 200 deluxe and the brake lights will sometimes stay on even with the car off and key out. I have replaced the hydraulic switch . Still doing it. Why would light stay on with car turned off?

I'm assuming your car hasn't been retrofitted with power brakes.

With manual brakes, a common cause of that problem is absence of brake pedal free play. With no pedal free play, release of the pedal does not allow the hydraulic pressure to be completely relieved, leaving enough for the switch to remain activated.

If that's your problem, it's a very simple adjustment of the pedal linkage.

And if adjusting the free play does not do it see if your cylinder has the same tiny orifice as prior year cylinders. The tiny hole or orifice in the photo in this post can become blocked with sediment or debris and cause the fluid to be trapped. The brake light can come on due to the hot fluid expanding and activating the switch if it cannot return to the reservoir.

Thanks I'll try those. Do the brake lights work with the car off and key out

Yes.

If brakes are adjusted too tight, the lights and brakes can come on with heat. The fluid expands.

I had the same problem on my 48 Plymouth. I'll just share what my problem was. After doing all of the tests and checks, it turned out to be a bad master cylinder. New cylinder, everything good. Good Luck.