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Brake Pedal Position (BPP) Switch Malfunction

DTC P0703, P1703 DETECTION CONDITION AND POSSIBLE CAUSE

DTC P0703, P1703 BRAKE PEDAL POSITION (BPP) SWITCH MALFUNCTION
DETECTION CONDITION 
  • P0703 indicates that the PCM did not receive a BPP input.
  • P01703 indicates the BPP signal was high (KOEO) or BPP signal did not cycle high and low (KOER).
POSSIBLE CAUSE 
  • Open or short in BPP circuit.
  • Open or short in stoplamp circuits.
  • Damaged PCM.
  • Malfunction in module(s) connected to BPP circuit.
  • Damaged brake switch.
  • Misadjusted brake switch.
HINT  BPP Switch Description 
  • Used by the PCM to disengage the transmission torque converter clutch and an input to the idle speed control for idle quality.
  • Hard wired to the PCM and supplies battery positive voltage (B+) when the vehicle brake pedal is applied.
G03988145Courtesy of MAZDA MOTORS CORP.
DTC P0703, P1703 INSPECTION

STEP INSPECTION ACTION
1
  • Was PCM Quick Test performed? 
 Yes If brake pedal was applied during KOEO Self Test, perform KOEO again and avoid applying brake pedal during test.
If brake pedal was not applied and released during KOER Self Test, perform KOER again and make sure to apply and release brake pedal.
For KOEO DTC P0703 or P173:
Go to next step. For KOER DTC P0703 or P173:
Go to next step 3.
All others:
Go to next step 4.
No Perform PCM Quick Test.
2 DTCS P0703 AND P1703: CHECK OPERATION OF STOPLAMPS
  • Apply and release the brake pedal several times and observe stoplamp operation.
  • Do brake lamps operate normally? 
 Yes Go to next step.
No For stoplamps never on:
Go to step 4.
For stoplamps always on:
Go to step 6.
3 CHECK FOR PCM BPP/BOO PID CYCLING
  • Key ON, Engine OFF (KOEO).
  • Access BPP/BOO PID with NGS Tester.
  • Apply and release brake pedal several times while viewing BPP/BOO PID.
  • Does the BPP/BOO PID cycle ON/OFF? 
 Yes See TEST 4: INTERMITTENT .
No Go to step 9.
4 CHECK FOR POWER TO BPP SWITCH
NOTE: Check the condition of the stoplamp bulbs before starting this test.
  • Disconnect BPP switch.
  • Measure B+ input voltage between FUSE 9 at the BPP switch and chassis ground.
  • Is voltage greater than 10 V? 
 Yes Go to next step.
No Verify integrity of fuse for B+ to brake pedal position switch. If OK, repair open in B+ circuit. If fuse is damaged, check B+ circuit, BPP circuit, stop lamp PWR circuit and any other associated circuits for short to ground. Refer to SYSTEM WIRING DIAGRAMS for B2500, SYSTEM WIRING DIAGRAMS for B3000, or SYSTEM WIRING DIAGRAMS for B4000 . Repair as necessary.
Go to step 10.
5 VERIFY INTEGRITY OF BPP SWITCH
  • Connect multimeter test probes to FUSE 9 and GND at the BPP switch.
  • Apply brake pedal while monitoring reading.
  • Is the resistance less than 5.0 ohms? 
 Yes Repair open circuit between BPP switch and stoplamp ground.
Go to step 10.
No Replace BPP switch.
Go to step 10.
6 VERIFY BPP SWITCH IS NOT ALWAYS CLOSED
  • Key OFF.
  • Disconnect BPP switch harness connector.
  • Key ON, Engine OFF (KOEO).
  • Are stoplamps still on? 
 Yes Go to next step.
No Verify proper installation of BPP switch.
If OK, replace switch.
Go to step 10.
7 CHECK FOR SHORT TO POWER IN PCM
  • Key OFF.
  • Disconnect PCM.
  • Key ON, Engine OFF (KOEO).
  • Are stoplamps still on? 
 Yes Go to next step.
No Replace PCM. See COMPUTERIZED ENGINE CONTROLS .
Go to step 10.
8 CHECK STOPLAMP CIRCUIT FOR SHORT TO POWER IN HARNESS
  • One at a time, disconnect all modules associated with the stoplamp circuit (PCM, cruise control, GEM, 4WABS and RABS). After disconnecting each module, turn key on and observe stoplamps. Turn key off. Repeat until each associated module has been disconnected or stoplamps turn off.
  • Did stoplamps turn off when any of the modules were disconnected? 
 Yes Go to SYSTEM WIRING DIAGRAMS for B2500, SYSTEM WIRING DIAGRAMS for B3000, or SYSTEM WIRING DIAGRAMS for B4000 and repair as necessary.
No Repair short to power in stoplamp circuit.
Go to step 10.
9 CHECK FOR BPP CIRCUIT CYCLING
  • Key OFF.
  • Disconnect PCM.
  • Install Breakout Box, leave PCM disconnected.
  • Measure voltage between PCM test pin 92 (BPP) and PCM test pin 77 (PWR GND) while applying and releasing the brake.
  • Does the voltage cycle? 
 Yes Replace PCM. See COMPUTERIZED ENGINE CONTROLS .
Go to step 10.
No Repair open in BPP circuit to PCM.
Go to step 10.
10 VERIFY TROUBLESHOOTING OF DTCs COMPLETED
  • Make sure to reconnect all disconnected connectors.
  • Clear DTCs from PCM memory using NGS tester generic OBD-II function.
  • Perform PCM Quick Test.
  • Is same DTC present? 
 Yes Replace PCM. See COMPUTERIZED ENGINE CONTROLS .
Repeat PCM Quick Test.
No If any other DTC is present, go to applicable DTC inspection.
If no DTC is present, troubleshooting complete.
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