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Home >> Mazda >> 2014 >> MX-5 Miata Club, Automatic Trans >> Repair and Diagnosis >> Engine Performance >> System >> On-Board Diagnostic [Engine Control System LF] >> DTC P0703

DTC P0703

DTC P0703  Brake switch input circuit problem 
DETECTION CONDITION 
  • The PCM monitors changes in input voltage from the brake switch No. 1. If the PCM does not the voltage changes while alternately accelerating and decelerating 8 times, the PCM determines that the brake switch No. 1 circuit has a malfunction.

Diagnostic support note 
  • This is a continuous monitor (CCM).
  • The MIL illuminates if the PCM detects the above malfunction condition in two consecutive drive cycles or in one drive cycle while the DTC for the same malfunction has been stored in the PCM.
  • PENDING CODE is available if the PCM detects the above malfunction condition during the first drive cycle.
  • FREEZE FRAME DATA (Mode 2/Mode 12) is available.
  • The DTC is stored in the PCM memory.
POSSIBLE CAUSE 
  • Brake switch connector or terminals malfunction
  • Open circuit or short to ground in brake switch No. 1 power supply circuit
    • Short to ground in wiring harness between battery positive terminal and brake switch terminal B
    • Brake switch No. 1 power supply circuit related fuse malfunction
    • Open circuit in wiring harness between battery positive terminal and brake switch terminal B
  • Short to ground in wiring harness between brake switch terminal D and PCM terminal 1AB
  • PCM connector or terminals malfunction
  • Short to power supply in wiring harness between brake switch terminal D and PCM terminal 1 AB
  • Open circuit in wiring harness between brake switch terminal D and PCM terminal 1AB
  • Brake switch malfunction
  • PCM malfunction
G07877641
DIAGNOSTIC PROCEDURE

STEP INSPECTION ACTION
1 VERIFY FREEZE FRAME DATA (MODE 12) HAS BEEN RECORDED 
  • Has the FREEZE FRAME DATA (Mode 12) been recorded?
 Yes Go to the next step.
No Record the FREEZE FRAME DATA (Mode 12) on the repair order, then go to the next step.
2 VERIFY RELATED SERVICE BULLETINS AVAILABILITY 
  • Verify related Service Bulletins availability.
  • Is any related Service Bulletins available?
 Yes Perform the repair or diagnosis according to the available Service Bulletins.
  • If the vehicle is not repaired, go to the next step.
No Go to the next step.
3 INSPECT BRAKE SWITCH CONNECTOR AND TERMINALS 
  • Turn the ignition switch off.
  • Disconnect the brake switch connector.
  • Inspect for poor connection (such as damaged/pulled-out pins, and corrosion).
  • Is there any malfunction?
 Yes Repair or replace the connector or terminals, then go to Step 9.
No Go to the next step.
4 INSPECT BRAKE SWITCH NO. 1 POWER SUPPLY CIRCUIT FOR OPEN CIRCUIT OR SHORT TO GROUND 
  • Brake switch connector is disconnected.
  • Turn the ignition switch to the ON position (Engine off).
  • Measure the voltage between brake switch terminal B (wiring harness-side) and body ground.
  • Is the voltage B+  ?
 Yes Go to the next step.
No Inspect the brake switch No. 1 power supply circuit related fuse.
  • If the fuse is melt:
    • Repair or replace the wiring harness for a possible short to ground.
    • Replace the fuse.
  • If the fuse is deterioration:
    • Replace the fuse.
  • If the fuse is normal:
    • Repair or replace the wiring harness for a possible open circuit

Go to Step 9.
5 INSPECT BRAKE SWITCH NO. 1 SIGNAL CIRCUIT FOR SHORT TO GROUND 
  • Brake switch connector is disconnected.
  • Turn the ignition switch off.
  • Inspect for continuity between brake switch terminal D (wiring harness-side) and body ground.
  • Is there continuity?
 Yes If the short to ground circuit could be detected:
  • Repair or replace the wiring harness for a possible short to ground.

If the short to ground circuit could not be detected:

Go to Step 9.
No Go to the next step.
6 INSPECT PCM CONNECTOR AND TERMINALS 
  • Disconnect the PCM connector.
  • Inspect for poor connection (such as damaged/pulled-out pins, and corrosion).
  • Is there any malfunction?
 Yes Repair or replace the connector or terminals, then go to Step 9.
No Go to the next step.
7 INSPECT BRAKE SWITCH NO. 1 SIGNAL CIRCUIT FOR SHORT TO POWER SUPPLY 
  • Brake switch and PCM connectors are disconnected.
  • Turn the ignition switch to the ON position (Engine off).
  • Measure the voltage between brake switch terminal D (wiring harness-side) and body ground.
  • Is there any voltage?
 Yes Repair or replace the wiring harness for a possible short to power supply, then go to Step 9.
No Go to the next step.
8 INSPECT BRAKE SWITCH NO. 1 SIGNAL CIRCUIT FOR OPEN CIRCUIT 
  • Brake switch and PCM connectors are disconnected.
  • Turn the ignition switch off.
  • Inspect for continuity between brake switch terminal D (wiring harness-side) and PCM terminal 1AB (wiring harness-side).
  • Is there continuity?
 Yes Replace the brake switch, then go to the next step.
(See BRAKE PEDAL REMOVAL/INSTALLATION ).
No Repair or replace the wiring harness for a possible open circuit, then go to the next step.
9 VERIFY TROUBLESHOOTING OF DTC P0703 COMPLETED 
  • Make sure to reconnect all disconnected connectors.
  • Clear the DTC from the PCM memory using the M-MDS.
  • Drive the vehicle 30 km/h {18.6 mph} or more.
  • Depress and release the brake pedal more than 8 times while driving the vehicle.
  • Is the PENDING CODE for this DTC present?
 Yes Replace the PCM, then go to the next step.
(See PCM REMOVAL/INSTALLATION ).
No Go to the next step.
10 VERIFY AFTER REPAIR PROCEDURE. 
 Yes Go to the applicable DTC inspection.
(See DTC TABLE ).
No DTC troubleshooting completed.
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