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P0504 code wont clear

Smokeyd4nn
Smokeyd4nn
in Ford Focus Club

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Hi on a 2010 tdci 1.6l i have code p0504 brake switch circuit a/b correlation ( brake lights still work fine btw )  i have replaced brake light switch but code will not clear with obd scanner it comes back as soon as car restarted even before brake pedal is touched. Any ideas please would resetting the pcm by disconnecting battery for a while possibly clear it ??

  • Quote


    5 hours ago, Smokeyd4nn said:

    i have code p0504 brake switch circuit a/b correlation ( brake lights still work fine btw )  i have replaced brake light switch but code will not clear with obd scanner

    I think there are two switches on the brake pedal, one is the brake light switch and the other is the brake pedal switch.

    The brake light switch drives the brake lights directly, and also goes to the ECU. The brake pedal switch goes to the Instrument Cluster. The ECU can read the brake pedal status over the CAN bus, so can compare the two, and flag up if it thinks there is an error. That is the only reason I can think of for that A/B error.

    If both have been replaced, it will need testing to be done for signals at each switch to see if there is a wiring fault in one.

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