Diagnostic Aids

WARNING: This page does not describe the selected car, but rather 32 other vehicles, including the 2003 Mercury Sable, 2003 Mercury Mountaineer, 2003 Mercury Marauder, 2003 Mercury Grand Marquis, and 2003 Lincoln Town Car. However, it is still accessible from the selected car via links, so may be relevant.

Perform this test when directed by QUICK TEST. This test is intended to diagnose:

Faulty BPP Switch
Faulty Brake Pressure Applied (BPA) Deactivator Switch
Wiring Harness Circuits (B(+), BPA, BPP, DBA, GND & Stoplamp PWR)
Powertrain Control Module (PCM)

Vehicles equip with stability assist will typically have the BPP switch input connected to the Anti-Lock Brake (ABS)-traction control\stability assist module. The stability assist portion of the ABS module will interpret the BPP switch input along with other ABS inputs and generate a output called the Driver Brake Application (DBA) signal. The DBA signal is typically sent to the PCM and to other BPP signal users. Correct stop lamp operation on stability assist equip vehicles are control by the ABS-traction control\stability assist module and\or stop lamp relay circuitry. When diagnosing these types of system always refer to the appropriate ANTI-LOCK article in BRAKES for ABS description and operation information and to the vehicle wiring schematic for BPP, DBA and stop lamp circuit information.

NOTE: On Town Car and Windstar, PCM receives BPP switch information through the Standard Corporate Protocol (SCP) link. This system test will only verify that self-test was performed correctly. For circuit wire color identification, see WIRING DIAGRAMS .

Fig 1: Identifying Brake Pedal Position Switch Circuits (Aviator, Explorer & Mountaineer - Without Stability Assist)

Courtesy of FORD MOTOR CO.

Fig 2: Identifying Brake Pedal Position Switch Circuits (Aviator - With Stability Assist)

Courtesy of FORD MOTOR CO.

Fig 3: Identifying Brake Pedal Position Switch Circuits (Blackwood, Excursion, Explorer Sport, Explorer Sport Trac, Pickup & Ranger)

Courtesy of FORD MOTOR CO.

Fig 4: Identifying Brake Pedal Position Switch Circuits (Expedition & Navigator)

Courtesy of FORD MOTOR CO.

Fig 5: Identifying Brake Pedal Position Switch Circuits (Explorer & Mountaineer - With Stability Assist)

Courtesy of FORD MOTOR CO.

Fig 6: Identifying Brake Pedal Position Switch Circuits (LS & Thunderbird Without Stability Assist)

Courtesy of FORD MOTOR CO.

Fig 7: Identifying Brake Pedal Position Switch Circuits (LS - With Stability Assist)

Courtesy of FORD MOTOR CO.

Fig 8: Identifying Brake Pedal Position Switch Circuits (Town Car & Windstar)

Courtesy of FORD MOTOR CO.

Fig 9: Identifying Brake Pedal Position Switch Circuits (All Others)

Courtesy of FORD MOTOR CO.