DYNAMIC RADAR CRUISE CONTROL SYSTEM, Diagnostic DTC:P0571

DESCRIPTION

• When the brake pedal is depressed, the stop light switch sends a signal to the ECM. When the ECM receives this signal, it cancels the cruise control. The fail-safe function operates to enable normal driving even if there is a malfunction in the stop light signal circuit. The cancellation condition occurs when voltage is applied to terminal STP. When the brake is applied, voltage is normally applied to terminal STP of the ECM through the STOP fuse and the stop light switch, and the ECM turns the cruise control off.

• The ECM receives the brake demand signal from the driving support ECU and transmits it to the skid control ECU. The skid control ECU receives a signal from the ECM and operates the brake actuator. The skid control ECU operates the brake actuator and at the same time illuminates the stop light by operating the stop light control relay.

WIRING DIAGRAM

INSPECTION PROCEDURE

PROCEDURE

1. CHECK STOP LIGHT OPERATION

   
   

   1. Check that the stop lights come on when the brake pedal is depressed, and go off when the brake pedal is released.

      OK
      Condition Illumination Condition Brake pedal depressed ON Brake pedal released OFF

   
   

   NG

   REPAIR OR REPLACE HARNESS OR CONNECTOR

   OK

2. READ VALUE USING INTELLIGENT TESTER (STOP LIGHT SWITCH)

   
   

   1. Connect the intelligent tester to the DLC3.

   2. Turn the engine switch on (IG).

   3. Turn the tester on.

   4. Enter the following menus: Powertrain / Radar Cruise / Data List.

   5. Check the Data List for proper functioning of the stop light switch.

      Radar Cruise

      Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
      Stp Light SW M-CPU	Stop light switch signal (Main CPU) / ON or OFF	OK: Brake pedal depressed OFF: Brake pedal released	-
      Brake Cancel Switch	Brake cancel signal / ON or OFF	OK: Brake pedal depressed OFF: Brake pedal released	-

      OK
      Display changes according to brake pedal operation described in above table.

   
   

   NG

   CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH POWER SOURCE CIRCUIT) Click here

   OK

3. CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH - SKID CONTROL ECU)

   
   

   1. Disconnect the stop light switch connector.

   2. Disconnect the skid control ECU connector.

   3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition A79-2 (L) - A44-2 (STP1) Always Below 1 Ω

      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition A79-2 (L) or A44-2 (STP1) - Body ground Always 10 kΩ or higher

   
   

   NG

   REPAIR OR REPLACE HARNESS OR CONNECTOR

   OK

4. CHECK HARNESS AND CONNECTOR (STOP LIGHT CONTROL RELAY - SKID CONTROL ECU)

   
   

   1. Disconnect the stop light control relay connector.

   2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition A52-1 (OUT) - A44-22 (STP2) Always Below 1 Ω A52-5 (STP) - A44-2 (STP1) Always Below 1 Ω A52-9 (ACC) - A44-31 (STP0) Always Below 1 Ω

      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition A52-1 (OUT) or A44-22 (STP2) - Body ground Always 10 kΩ or higher A52-5 (STP) or A44-2 (STP1) - Body ground Always 10 kΩ or higher A52-9 (ACC) or A44-31 (STP0) - Body ground Always 10 kΩ or higher

   
   

   NG

   REPAIR OR REPLACE HARNESS OR CONNECTOR

   OK

5. INSPECT STOP LIGHT CONTROL RELAY

   
   

   1. Inspect the stop light control relay Click here.

   
   

   NG

   REPLACE STOP LIGHT CONTROL RELAY Click here

   OK

6. REPLACE BRAKE ACTUATOR ASSEMBLY (SKID CONTROL ECU)

   
   

   1. Replace the brake actuator (skid control ECU) Click here.

   
   

   NEXT

7. CHECK DTC OUTPUT

   
   

   1. Clear the DTCs Click here.

   2. Perform the following to make sure that the DTC detection conditions are met.

      Tech Tips

      If the detection conditions are not met, the malfunction cannot be detected.

      
      

      1. Drive the vehicle at a speed of 50 km/h (31 mph) or more.

      2. Turn the cruise control main switch on.

      3. Push the -SET switch to activate the cruise control.

   3. Check for DTCs Click here.

      Result
      Result Proceed to DTC is not output A DTC P0571 is output B

   
   

   B

   REPLACE ECM Click here

   A

   END

8. CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH POWER SOURCE CIRCUIT)

   
   

   1. Disconnect the stop light switch connector.

   2. 

      Text in Illustration

      *1	Front view of wire harness connector (to Stop Light Switch)

      Measure the voltage and resistance according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Condition Specified Condition A79-1 (B) - A79-3 (GND) Engine switch off 11 to 14 V A79-5 (B) - A79-3 (GND) Engine switch on (IG) 11 to 14 V

      Standard Resistance
      Tester Connection Condition Specified Condition A79-3 (GND) - Body ground Always Below 1 Ω

   
   

   NG

   REPAIR OR REPLACE HARNESS OR CONNECTOR

   OK

9. INSPECT STOP LIGHT SWITCH

   
   

   1. Connect the stop light switch.

   2. 

      Text in Illustration

      *1	Component with harness connected (Stop Light Switch)

      Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Condition Specified Condition A79-2 (L) - A79-3 (GND) Engine switch off, Brake pedal not depressed Below 1 V Engine switch off, Brake pedal depressed 11 to 14 V A79-4 (L) - A79-3 (GND) Engine switch on (IG), Brake pedal not depressed 11 to 14 V Engine switch on (IG), Brake pedal depressed Below 1 V

   
   

   NG

   REPLACE STOP LIGHT SWITCH Click here

   OK

10. CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH - ECM)

    
    

    1. Disconnect the ECM connector.

    2. Disconnect the stop light switch connector.

    3. Disconnect the stop light control relay connector.

    4. Disconnect the skid control ECU connector.

    5. Measure the resistance according to the value(s) in the table below.

       Standard Resistance (Check for Open)
       Tester Connection Condition Specified Condition A43-36 (STP) - A79-2 (L) Always Below 1 Ω A43-35 (ST1-) - A79-4 (L) Always Below 1 Ω

       Standard Resistance (Check for Short)
       Tester Connection Condition Specified Condition A43-36 (STP) or A79-2 (L) - Body ground Always 10 kΩ or higher A43-35 (ST1-) or A79-4 (L) - Body ground Always 10 kΩ or higher

    
    

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE ECM Click here