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Home >> Mazda >> 2001 >> B2500 SE, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> System Tests >> Test FD: Brake Pedal Position Switch >> Diagnostic Aids

Diagnostic Aids

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

To prevent replacement of good components, be aware following non-EEC related areas may be at fault:

  1. 1) KOER DTC P0703 Or P1703: Verify Brake Pedal Was Depressed

    These DTCs indicate that when brake pedal was applied during KOER ON-DEMAND SELF-TEST, BPP signal did not cycle high and low. Possible causes for this fault are:
    • Open Or Short In BPP Circuit
    • Open Or Short In Brakelight Circuit
    • Faulty Powertrain Control Module (PCM)
    • Faulty BPP Switch
    • Misadjusted Brake Switch
    • Brake Pedal Not Applied During KOER ON-DEMAND SELF-TEST.

    If brake pedal was not applied and released during KOER ON-DEMAND SELF-TEST , repeat test. Depress and release brake pedal only once during test. If brake pedal was applied and released during KOER ON-DEMAND SELF-TEST, go to step  3).

  2. 2) KOEO DTC P0703 Or P1703

    These DTCs indicate that BPP signal voltage was high during KOEO ON-DEMAND SELF-TEST. Possible causes for these faults are:
    • Open Or Short In BPP Circuit
    • Open Or Short In Brakelight Circuit
    • Faulty Powertrain Control Module (PCM)
    • Faulty BPP Switch
    • Misadjusted Brake Switch
    • Brake Pedal Applied During Entire KOEO ON-DEMAND SELF-TEST

    If brake pedal was applied during KOEO ON-DEMAND SELF-TEST, repeat test. DO NOT apply brake pedal during KOEO ON-DEMAND SELF-TEST. If brake pedal was not applied during KOEO ON-DEMAND SELF-TEST, go to next step.

  3. 3) Continuous Memory DTCs P0703, P1572 Or P1703: Check Operation Of Brakelights

    This DTC indicates brake input rationality tests (one or both BPA or BPP switch inputs to PCM) failed to change when expected. Possible causes for this fault are:
    • Misadjusted Brake Switch
    • Blown Fuse
    • Faulty BPP Switch
    • Faulty BPA Switch
    • Open Or Short In BPP Circuit
    • Open Or Short In BPA Circuit
    • Faulty Powertrain Control Module (PCM)

    Check operation of brakelights. If brakelights operate normally, go to next step. If brakelights do not operate properly, go to step  5) for brakelights inoperative, or step  7) for brakelights always on.

  4. 4) Check For PCM BPP PID Cycling

    Turn ignition switch to OFF position. Connect scan tool to Data Link Connector (DLC). Turn ignition switch to ON position. Using scan tool, select BPP PID from PID/DATA MONITOR & RECORD menu. If BPP PID is not available, go to step  10). While observing BPP PID, apply and release brake pedal several times. If BPP PID does not cycle ON and OFF, go to step  10). If BPP PID cycles ON and OFF, go to TEST Z, step  1).

  5. 5) Check B+ Voltage To BBP Switch

    Ensure brakelight bulbs are good. Disconnect BPP switch (located on brake pedal). Using a DVOM, measure B+ input voltage between chassis ground and BPP switch harness connector. If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, check fuse for B+ to BPP switch. If fuse is okay, repair open in B+ circuit to BPP switch. If fuse is blown, repair short to ground in B+, BPP or brakelight PWR circuit. See EXTERIOR LIGHTS article.

  6. 6) Check BPP Switch

    Depress brake pedal. Using a DVOM, measure resistance between appropriate BPP switch terminals. See WIRING DIAGRAMS article. If resistance is 5 ohms or more, replace BPP switch. If resistance is less than 5 ohms, repair open circuit between BPP switch and brakelight ground.

  7. 7) Verify BPP Switch Is Not Always Closed

    Ensure ignition switch is turned to OFF position. Disconnect BPP switch (located on brake pedal). Turn ignition switch to ON position. If brakelights are still on, go to next step. If brakelights are off, verify correct installation of BPP switch. If installation is okay, replace BPP switch.

  8. 8) Check For Short To Power In PCM

    Turn ignition switch to OFF position. Disconnect PCM connector(s). Turn ignition switch to ON position. Check brakelights. If brakelights are still on, go to next step. If brakelights are off, replace PCM.

  9. 9) Check For Short To Power

    Turn ignition switch to OFF position. Ensure PCM and BPP switch are disconnected. One at a time, disconnect all modules associated with brakelight circuit. See WIRING DIAGRAMS article. After disconnecting each module, turn ignition switch to ON position and check brakelights. Turn ignition switch to OFF position. Repeat until each associated module has been disconnected or brakelights turn off. If brakelights are still on after disconnecting all associated modules, repair short to VPWR in brakelight circuit. See EXTERIOR LIGHTS article in ACCESSORIES & EQUIPMENT. If brakelights are off with associated module(s) disconnected, diagnose appropriate module and/or related system. See SELF-DIAGNOSTIC SYSTEM in appropriate AUTOLAMP SYSTEMS article in ACCESSORIES & EQUIPMENT to diagnose system associated with module that was disconnected to eliminate short to VPWR. Repair system or replace module as necessary.

  10. 10) Check For BPP Circuit Cycling

    Turn ignition switch to OFF position. Disconnect PCM connector(s). Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Using a DVOM, measure voltage between chassis ground and PCM harness connector terminal No. 92 while applying and releasing brake pedal. If voltage does not cycle, repair open in BPP circuit to PCM. If voltage cycles, replace PCM.

  11. 11) Check For BPA Circuit Cycling

    Ensure PCM connectors are disconnected. Using a DVOM, measure voltage between chassis ground and PCM harness connector terminal No. A28 while applying and releasing brake pedal. If voltage does not cycle, go to next step. If voltage cycles, replace PCM.

  12. 12) Check BPA Circuit For Open

    Disconnect BPA deactivator switch harness connector. Using a DVOM, measure resistance of BPA circuit between PCM harness connector terminal No. A28 and BPA deactivator switch harness connector terminal. See WIRING DIAGRAMS article. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in BPA circuit to PCM.

  13. 13) Check BPA Deactivator Switch

    Using a DVOM, measure resistance between BPP switch terminals while applying and releasing brake pedal. With brake pedal applied, resistance should be more than 10 k/ohms. With brake pedal released, resistance should be less than 5 ohms. If resistance is as specified, repair VPWR circuit to BPA deactivator switch. If resistance is not as specified, replace BPA deactivator switch.
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