I am trying to figure out why my brake lights stay on after I push the brakes. I can go and push the pedal a few times and they will turn off. it is a new brake light pressure switch and when I changed it I did not bleed brakes again "which I will do soon" but I am wondering if this is a pressure issue or a faulty brake light switch issue or a pedal sticking issue. the whole board has been helpful with my questions to get this car going right. thank you for your time.
Like alchemy says.....if you pull up your pedal by hand do the lights go out? Could be spring or adjustment.
That switch is usually pressure (hydraulic) operated. If the brakes need to be bled, sure, bleed them first. There may also be some crud in the line that is blocking the fluid releasing pressure from the switch. Pull it off and check. Look inside the master cylinder with a flashlight. At the bottom there are small holes that relieve pressure when the peddle is released. They may be plugged. Was this problem the reason for changing the switch? If it worked correctly before it could be a bad switch.
I got surprised after hearing of a 'common problem' with pressure switches. My NAPA parts man said there was a memo about bad brake pressure switches from various sources. A whole 'run' of them.
Usually indicates pressure build up not allowing fluid to return to the mc. Perhaps old rubber flex lines deteriorating, Tue will allow fluid under pressure to flow but restrict return. Might be debris block in the return poet in thee mc. Could be a faulty new switch. This Chinese and Mexican made stuff they let in these days is always a craps shoot. Ant brake drag when the light sticks??? Give some thought to using a universal mechanicals switch.
Two things could cause your problem, bad switch or residual pressure when you take your foot off the brake. Bad switch.. replace. Pressure problem, there have been several suggestions already posted, I might add flushing the hydraulic system, which is just bleeding the system a lot. Doesn’t take much residual pressure to keep the light on. Bones
I got a bad one from Napa myself. Just about anything I've gotten from Napa for my Ford has shit the bed on me.
I brought an expensive pressure switch from Bob Drake. I was told that was a bad idea, so I double wired for a mechanical switch but didn’t install it. The pressure switch lasted 2 months. I fitted a mechanical one. Been fine ever since. Sent from my iPhone using H.A.M.B.
The pressure switch that came on my Wilwood proportioning valve on my 40 coupe lasted about 2 months before it went south. The Auto Zone replacement is still working.
I've had a lot of trouble with the pressure switches on my Ford. I can't count how many I've replaced. I don't think the quality is very high, and I buy good ?? switches. It could be a bad switch. I also was working on a Dodge last summer that the brake lights would stay on. The owner had replaced the master cylinder and was unaware that the push rod might need adjusting to give him some free play so the master could release its pressure. Built up pressure was holding the brake light switch on.
Another vote for return spring. If the brake lights are on and you can reach in and pull the pedal back and they go out that is your problem. I put a Ford pressure brake light switch on my 48 Chev when I put the dual master cylinder in and replaced it about every two years after that. they don't tend to last too long and if they are down under the car next to a frame mounted master cylinder that time is cut shorter. I'll go back to a stock switch on the rebuild.
I got one with my PV too, that leaked from day 1. Onto the Napa unit that took too much pedal pressure to trip. I got one on eBay, I should get another. It was around $12 and takes 45 PSI to actuate.
ford used 'em for a long time, but i'm not crazy about pressure brake switches. a leak waiting to happen.
I ran pressure switches in lots of cars and once in a while an old one would fail. I have had only 2 fail on me in recent years and both were brand new. Hecho en China... The one I have now acts quickly and comes on as soon as I move the pedal, well before the stopping power comes in.