DTC P0571

DTC P0571	Brake switch input circuit problem
DETECTION CONDITION	The PCM monitors the input signal from brake switch NO. 1 and brake switch NO. 2 when the engine is running. If both input signals remain on or off, the PCM determines that there is a brake switch input circuit problem. Diagnostic support note This is a continuous monitor (other). The MIL does not illuminate. FREEZE FRAME DATA (Mode 2/Mode 12) is not available. The DTC is stored in the PCM memory.
POSSIBLE CAUSE	With ABS HU/CM ABS HU/CM malfunction Brake switch connector or terminals malfunction Short to ground or open circuit 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 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 ABS HU/CM terminal Y Brake switch malfunction ABS HU/CM connector or terminals malfunction Short to power supply in wiring harness between brake switch terminal D and ABS HU/CM terminal Y Open circuit in wiring harness between brake switch terminal D and ABS HU/CM terminal Y PCM malfunction With DSC HU/CM DSC HU/CM malfunction Brake switch connector or terminals malfunction Short to ground or open circuit 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 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 DSC HU/CM terminal N Brake switch malfunction DSC HU/CM connector or terminals malfunction Short to power supply in wiring harness between brake switch terminal D and DSC HU/CM terminal N Open circuit in wiring harness between brake switch terminal D and DSC HU/CM terminal N PCM malfunction

DIAGNOSTIC PROCEDURE

STEP	INSPECTION		ACTION
1	VERIFY RELATED REPAIR INFORMATION AVAILABILITY Verify related Service Bulletins and/or on-line repair information availability. Is any related repair information available?	Yes	Perform repair or diagnosis according to the available repair information. If the vehicle is not repaired, go to the next step.
1		No	Go to the next step.
2	VERIFY RELATED PENDING CODE OR STORED DTC Turn the ignition switch off, then to the ON position (engine off). Verify the related PENDING CODE or stored DTCs. Are other DTCs present?	Yes	Go to the appropriate DTC inspection. (See DTC TABLE ).
2		No	Go to the next step.
3	VERIFY STORED DTC FOR ABS HU/CM OR DSC HU/CM Verify stored DTC for the ABS HU/CM or DSC HU/CM. (See ON-BOARD DIAGNOSIS [ABS] ). (See ON-BOARD DIAGNOSIS [DYNAMIC STABILITY CONTROL (DSC)] ). Are DTCs stored?	Yes	Go to the appropriate DTC inspection. (See ON-BOARD DIAGNOSIS [ABS] ). (See ON-BOARD DIAGNOSIS [DYNAMIC STABILITY CONTROL (DSC)] ).
3		No	Go to the next step.
4	INSPECT BRAKE SWITCH CONNECTOR FOR POOR CONNECTION Turn the ignition switch off. Disconnect the brake switch connector. Inspect for poor connection (such as damaged/pulled-out pins, corrosion) Is there any malfunction?	Yes	Repair or replace the connector and/or terminals, then go to Step 11.
4		No	Go to the next step.
5	INSPECT BRAKE SWITCH NO. 1 POWER SUPPLY CIRCUIT FOR SHORT TO GROUND OR OPEN CIRCUIT 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.
5		No	Inspect the brake switch NO. 1 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 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: Replace the PCM (short to ground in the PCM internal circuit). (See PCM REMOVAL/INSTALLATION ). Go to Step 11.
6		No	Go to the next step.
7	INSPECT BRAKE SWITCH NO. 1 CAUTION: If the brake switch is removed from the brake pedal or the interlock unit, its proper functioning cannot be guaranteed when reinstalled. Therefore, inspect the brake switch with it still installed, or replace the brake switch if it is removed. Inspect the brake switch NO. 1. (See BRAKE SWITCH INSPECTION ). Is there any malfunction?	Yes	Replace the brake switch, then go to Step 11. (See BRAKE PEDAL REMOVAL/INSTALLATION ).
7		No	Go to the next step.
8	INSPECT ABS HU/CM OR DSC HU/CM CONNECTOR FOR POOR CONNECTION Turn the ignition switch off. Disconnect the ABS HU/CM or DSC HU/CM connector. Inspect for poor connection (such as damaged/pulled-out pins, corrosion). Is there any malfunction?	Yes	Repair or replace the connector and/or terminals, then go to Step 11.
8		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 the voltage B+ ?	Yes	Repair or replace the wiring harness for a possible short to power supply, then go to Step 11.
9		No	Go to the next step.
10	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 the following circuits: Brake switch terminal D (wiring harness-side) and ABS HU/CM terminal Y (wiring harness-side) (with ABS HU/CM) Brake switch terminal D (wiring harness-side) and DSC HU/CM terminal N (wiring harness-side) (with DSC HU/CM) Is there continuity?	Yes	Go to the next step.
10		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. (See AFTER REPAIR PROCEDURE ). Turn the ignition switch to the ON position (engine off). Depress the brake pedal more than 5 times. Perform the KOEO or KOER self test. (See KOEO/KOER SELF TEST ). Is the same DTC present?	Yes	Replace the PCM, then go to the next step. (See PCM REMOVAL/INSTALLATION ).
11		No	Go to the next step.
12	VERIFY AFTER REPAIR PROCEDURE Perform the "AFTER REPAIR PROCEDURE ". (See AFTER REPAIR PROCEDURE ). Are any DTCs present?	Yes	Go to the applicable DTC inspection. (See DTC TABLE ).
12		No	DTC troubleshooting completed.