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DTC P0571

DTC P0571  Brake switch circuit problem 
DETECTION CONDITION 
  • The PCM monitors changes in input voltage for brake switch No. 1 and No. 2. If the PCM detects that both brake switches No. 1 and No. 2 remain on or off for 15 s  , it determines that the brake switch circuit has a malfunction.

Diagnostic support note 
  • This is a continuous monitor (other).
  • The MIL does not illuminate.
  • 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 in wiring harness between brake switch terminal C and body ground
  • Open circuit or short to ground in brake switch power supply circuit
    • Short to ground in wiring harness between battery positive terminal and brake switch terminal B
    • Brake switch 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 1 AB
  • Short to ground in wiring harness between brake switch terminal A and PCM terminal 1AF
  • PCM connector or terminals malfunction
  • Brake switch No. 1 signal circuit and No. 2 signal circuit are shorted to each other
  • 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
  • Open circuit in wiring harness between brake switch terminal A and PCM terminal 1 AF
  • Brake switch malfunction
  • PCM malfunction
G07877638
DIAGNOSTIC PROCEDURE

STEP INSPECTION ACTION
1 VERIFY FREEZE FRAME DATA (MODE 12) AND DIAGNOSTIC MONITORING TEST RESULTS HAVE BEEN RECORDED 
  • Have the FREEZE FRAME DATA (Mode 12) and DIAGNOSTIC MONITORING TEST RESULTS (other related) been recorded?
 Yes Go to the next step.
No Record the FREEZE FRAME DATA (Mode 12) and DIAGNOSTIC MONITORING TEST RESULTS 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 11.
No Go to the next step.
4 INSPECT BRAKE SWITCH NO. 2 GROUND CIRCUIT FOR OPEN CIRCUIT 
  • Brake switch connector is disconnected.
  • Inspect for continuity between brake switch terminal C (wiring harness-side) and body ground.
  • Is there continuity?
 Yes Go to the next step.
No Repair or replace the wiring harness for a possible open circuit, then go to Step 11.
5 INSPECT BRAKE SWITCH 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 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 11.
6 INSPECT BRAKE SWITCH NO. 1 AND NO. 2 SIGNAL CIRCUITS FOR SHORT TO GROUND 
  • Brake switch connector is disconnected.
  • Turn the ignition switch off.
  • Inspect for continuity between the following terminals (wiring harness-side) and body ground:
    • Brake switch terminal D
    • Brake switch terminal A
  • 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:

  • Replace the PCM (short to ground in PCM internal circuit).

    (See PCM REMOVAL/INSTALLATION ).


Go to Step 11.
No Go to the next step.
7 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 11.
No Go to the next step.
8 INSPECT BRAKE SWITCH NO. 1 AND NO. 2 SIGNAL CIRCUITS FOR SHORT TO EACH OTHER 
  • Brake switch and PCM connectors are disconnected.
  • Inspect for continuity between brake switch terminal D and A (wiring harness-side).
  • Is there continuity?
 Yes Repair or replace the wiring harness for a possible short to each other, then go to Step 11.
No Go to the next step.
9 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 11.
No Go to the next step.
10 INSPECT BRAKE SWITCH NO. 1 AND NO. 2 SIGNAL CIRCUITS FOR OPEN CIRCUIT 
  • Brake switch and PCM connectors are disconnected.
  • Turn the ignition switch off.
  • Inspect for continuity between the following terminals (wiring harness-side):
    • Brake switch terminal D and PCM terminal 1AB
    • Brake switch terminal A and PCM terminal 1AF
  • 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.
11 VERIFY TROUBLESHOOTING OF DTC P0571 COMPLETED 
  • Make sure to reconnect all disconnected connectors.
  • Clear the DTC from the PCM memory using the M-MDS.
  • Turn the ignition switch to the ON position (Engine off).
  • Depress and release the brake pedal more than 15 sec. for 5 times.
  • Is the same DTC present?
 Yes Replace the PCM, then go to the next step.
(See PCM REMOVAL/INSTALLATION ).
No Go to the next step.
12 VERIFY AFTER REPAIR PROCEDURE 
 Yes Go to the applicable DTC inspection.
(See DTC TABLE ).
No DTC troubleshooting completed.
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