Part 1

CRUISE CONTROL: DYNAMIC RADAR CRUISE CONTROL SYSTEM: P0571,P0571: Stop Light Switch Circuit Malfunction
P0571 - Brake Switch "A" Circuit

DESCRIPTION

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

- The ECM receives the brake demand signal from the distance control 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 lights by operating the stop light control relay.





WIRING DIAGRAM









INSPECTION PROCEDURE

NOTICE:
Inspect the fuses for circuits related to this system before performing the following inspection procedure.

PROCEDURE

1. CHECK ECM (TERMINAL VOLTAGE)

(a) Disconnect the ECM connectors.





(b) Turn the engine switch on (IG).

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

Standard Voltage:





Text in Illustration





(d) Reconnect the ECM connectors.

NG -- CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY POWER SOURCE)
OK -- Continue to next step.

2. CHECK BRK-LP RELAY

(a) Remove the BRK-LP relay from the No. 2 engine room relay block.





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

Standard Resistance:





Text in Illustration





(c) Reinstall the BRK-LP relay.

NG -- REPLACE BRK-LP RELAY
OK -- Continue to next step.

3. CHECK HARNESS AND CONNECTOR (STOP LIGHT CONTROL RELAY POWER SOURCE)

(a) Disconnect the stop light control relay connector.





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

Standard Voltage:





Text in Illustration





(c) Reconnect the stop light control relay connector.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT CONTROL RELAY - STOP SW FUSE)
OK -- Continue to next step.

4. CHECK HARNESS AND CONNECTOR (STOP LIGHT CONTROL RELAY - BODY GROUND)

(a) Disconnect the stop light control relay connector.





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

Standard Resistance:





Text in Illustration





(c) Reconnect the stop light control relay connector.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT CONTROL RELAY - BODY GROUND)
OK -- Continue to next step.

5. CHECK HARNESS AND CONNECTOR (STOP LIGHT CONTROL RELAY - STOP LIGHT SWITCH ASSEMBLY)

(a) Disconnect the stop light control relay connector.





(b) Disconnect the stop light switch assembly connector.

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

Standard Resistance (Check for Open):





Standard Resistance (Check for Short):





Text in Illustration





(d) Reconnect the stop light switch assembly connector.

(e) Reconnect the stop light control relay connector.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT CONTROL RELAY - STOP LIGHT SWITCH ASSEMBLY)
OK -- Continue to next step.

6. CHECK HARNESS AND CONNECTOR (STOP LIGHT CONTROL RELAY - BLK-LP RELAY)

(a) Disconnect the stop light control relay connector.





(b) Remove the BRK-LP relay from the No. 2 engine room relay block.

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

Standard Resistance (Check for Open):





Standard Resistance (Check for Short):





Text in Illustration





(d) Reconnect the stop light control relay connector.

(e) Reinstall the BRK-LP relay.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT CONTROL RELAY - BRK-LP RELAY)
OK -- Continue to next step.

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

(a) Disconnect the stop light switch assembly connector.





(b) Disconnect the skid control ECU connector.

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

Standard Resistance (Check for Open):





Standard Resistance (Check for Short):





Text in Illustration





(d) Reconnect the stop light switch assembly connector.

(e) Reconnect the skid control ECU connector.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - SKID CONTROL ECU)
OK -- Continue to next step.

8. CHECK HARNESS AND CONNECTOR (BRK-LP RELAY - SKID CONTROL ECU)

(a) Remove the BRK-LP relay from the No. 2 engine room relay block.





(b) Disconnect the skid control ECU connector.

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

Standard Resistance (Check for Open):





Standard Resistance (Check for Short):





Text in Illustration





(d) Reinstall the BRK-LP relay.

(e) Reconnect the skid control ECU connector.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (BRK-LP RELAY - SKID CONTROL ECU)
OK -- Continue to next step.

9. CHECK BRK-LP RELAY (TERMINAL VOLTAGE)

(a) Remove the BRK-LP relay from the No. 2 engine room relay block.





(b) Turn the engine switch on (IG).

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

Standard Voltage:





Text in Illustration





(d) Reinstall the BRK-LP relay.

NG -- INSPECT MAIN BODY ECU LH (LH-IG1 RELAY)
OK -- Continue to next step.

10. INSPECT STOP LIGHT CONTROL RELAY

(a) Inspect the stop light control relay Testing and Inspection.

NG -- REPLACE STOP LIGHT CONTROL RELAY
OK -- Continue to next step.

11. REPLACE BRAKE ACTUATOR ASSEMBLY (SKID CONTROL ECU)

(a) Replace the brake actuator assembly (skid control ECU) Removal.

NEXT -- Continue to next step.

12. CHECK WHETHER DTC OUTPUT RECURS (DTC P0571)

(a) Connect the Techstream to the DLC3.

(b) Turn the engine switch on (IG).

(c) Turn the Techstream on.

(d) Clear the DTCs Dynamic Radar Cruise Control System.

(e) Perform the following to make sure that the DTC detection conditions are met.

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

(1) Drive the vehicle at a speed of 50 km/h (30 mph) or more.

(2) Turn the cruise control main switch on.

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

(f) Enter the following menus: Powertrain / Radar Cruise / Trouble Codes.

(g) Read the DTCs Dynamic Radar Cruise Control System.

Result:





C -- REPLACE ECM (for 4GR-FSE) Removal

B -- REPLACE ECM (for 2GR-FSE) Removal

A -- END