Brake Fluid Level Switch?

2012 Expedition.
I have the Red Brake Warning indicator (when the parking brake is OFF). It seems to be temperature related because when the car sits at idle, or heat soaks after shutoff, the warning comes on. Then when I drive and get airflow, the warning goes away. From the list of faulty items that cause the warning to turn on (from the service manual), I suspect either the brake fluid level switch or the booster vacuum sensor. I figured I would try replacing the brake fluid level switch first.

Does anyone know what the part number is for the switch? The service manual doesn't mention it and I'm coming up empty at various parts websites. I'm starting to think this only comes integrated with the master cylinder.

Requires changing the whole master cylinder out?

Thanks!

With a proper scan tool you can get the specific readings from each switch in real time, rather than throwing parts at the problem.

Anyone know if the Ancel FD500 ($99) will do that? They claim it scans info related to all Ford subsystems. "Diagnose All Controlled Modules of a Ford, including Check Engine, Brake, Parking Brake, Airbag, Transmission,HAVC, etc." But does it really? Maybe I'll try one and return if it doesn't.

Learn about FORscan. It's free...

Thanks for the recommendation. That's exactly what I need! On it...

@Trainmaster
Thanks again for the FORScan suggestion. I dove in with the OBDLink MX+ adapter ($139) and got the Forscan app ($5) on my phone. Saw that the ABS module is setting DTC C109E (Vacuum Sensor Circuit Fault). New sensor on the way.

Much easier sensor to replace since the fluid level switch for this vehicle doesn't exist without a new master cylinder attached.

Glad it worked. Good diagnostic stuff can save lots of work and money, and these cars are all about diagnostics.

Ford Parts Giant
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