new brake switch, now wrench light

Posted by: ianhmcgill

new brake switch, now wrench light - 05/19/21 01:36 AM

Hi guys, 2011 Crown Victoria LX w 133k. Replaced the OEM brake light switch with a really cheap one off rockauto because the old one was kind of faulty and wouldn't consistently stay on if I didnt have all the pressure in the world on the brake pedal. Now the wrench light comes on while im driving, and no more cruise control. Car still drives perfectly fine w no speed cap on the highway. Is this a problem that I need to have fixed in order to prevent it from going into limp-home mode in the future? Can this problem cause unintended acceleration?
Posted by: Davidzq

Re: new brake switch, now wrench light - 05/19/21 11:59 AM

That's an interesting issue. Sounds like the new brake switch is bad.
There's two sets of contacts. One for the lights, and one for the shift interlock and sends a signal to the LCM.
This signal is used as a redundant cruise control deactivation (in addition to the dedicated cruise deactivation switch at the top of the brake pedal), and for various programming procedures that require a brake pedal test.
Sounds like this second contact isn't working.