DESCRIPTION
WIRING DIAGRAM
INSPECTION PROCEDURE
INSPECT FUSE (STOP, IGN, ECU-IG No. 2)
READ VALUE USING INTELLIGENT TESTER (STOP LIGHT SWITCH)
INSPECT BRAKE LIGHT RELAY (BRK LP)
CHECK HARNESS AND CONNECTOR (STOP LIGHT CONTROL RELAY - BATTERY AND BODY GROUND)
CHECK HARNESS AND CONNECTOR (STOP LIGHT CONTROL RELAY - STOP LIGHT SWITCH)
CHECK HARNESS AND CONNECTOR (STOP LIGHT CONTROL RELAY - BRAKE LIGHT RELAY)
CHECK STOP LIGHT CONTROL RELAY
CHECK HARNESS AND CONNECTOR (BRAKE LIGHT RELAY - BATTERY)
CHECK HARNESS AND CONNECTOR (BRAKE LIGHT RELAY, STOP LIGHT CONTROL RELAY - MASTER CYLINDER SOLENOID)
INSPECT STOP LIGHT SWITCH
CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH - BATTERY)
CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH - ECM)
DTC P0571 Stop Light Switch Circuit Malfunction
DESCRIPTION
The ECM receives the brake demand signal from the stop light switch and transmits it to the master cylinder solenoid (skid control ECU). The master cylinder solenoid (skid control ECU) receives the signal from the ECM and operates the brake actuator. 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 applied to terminal STP of the ECM through the STOP fuse and the stop light switch, and the ECM turns the cruise control off.
| DTC Code | DTC Detection Condition | Trouble Area |
| P0571 | This trouble code is output when the ECM detects the brake light relay error signal from the master cylinder solenoid (skid control ECU) for 0.2 seconds. or more while the dynamic radar cruise control is in operation.
When the voltage of the STP terminal and the ST1- terminal of the ECM is below than 1 V for 0.5 seconds. or more.
| Fuse (STOP, IGN, ECU-IG No. 2)
Stop light switch
Brake light relay
Stop light control relay
Master cylinder solenoid (skid control ECU)
Harness or connector
ECM
|
WIRING DIAGRAM
INSPECTION PROCEDURE
| 1.INSPECT FUSE (STOP, IGN, ECU-IG No. 2) |
Remove the STOP and IGN fuses from the engine room relay block.
Remove the ECU-IG No. 2 fuse from the cowl side junction block LH.
Measure the resistance according to the value(s) in the table below.
- Standard Resistance:
| Tester Connection | Condition | Specified Condition |
| STOP fuse | Always | Below 1 Ω |
| IGN fuse |
| ECU-IG No. 2 fuse |
| 2.READ VALUE USING INTELLIGENT TESTER (STOP LIGHT SWITCH) |
Using the intelligent tester, read the Data List ().
Radar Cruise| Tester Display | Measurement Item/Range | Normal Condition | Diagnostic Note |
| Stop Light SW M-CPU |
Stop light switch signal (Main CPU) /
ON or OFF |
ON: Brake pedal depressed
OFF: Brake pedal released | - |
- OK:
- Normal conditions listed above are displayed.
| 3.INSPECT BRAKE LIGHT RELAY (BRK LP) |
Remove the brake light relay from the engine room relay block.
Measure the resistance according to the value(s) in the table below.
- Standard Resistance:
| Tester Connection | Condition | Specified Condition |
| 3 - 4 |
Battery voltage is applied to terminals 1 and 2 | 10 kΩ higher |
| Battery voltage is not applied to terminals 1 and 2 | Below 1 Ω |
| 3 - 5 |
Battery voltage is not applied to terminals 1 and 2 | 10 kΩ higher |
| Battery voltage is applied to terminals 1 and 2 | Below 1 Ω |
| | REPLACE BRAKE LIGHT RELAY |
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| 4.CHECK HARNESS AND CONNECTOR (STOP LIGHT CONTROL RELAY - BATTERY AND BODY GROUND) |
Disconnect the A39 stop light control relay connector.
Measure the voltage according to the value(s) in the table below.
- Standard Voltage:
| Tester Connection | Condition | Specified Condition |
| A39-6 (+B) - Body ground | Always | 11 to 14 V |
Measure the resistance according to the value(s) in the table below.
- Standard Resistance:
| Tester Connection | Condition | Specified Condition |
| A39-4 (GND) - Body ground | Always | Below 1 Ω |
| | REPAIR OR REPLACE HARNESS OR CONNECTOR |
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| 5.CHECK HARNESS AND CONNECTOR (STOP LIGHT CONTROL RELAY - STOP LIGHT SWITCH) |
Disconnect the A39 stop light control relay connector.
Disconnect the A30 stop light switch connector.
Measure the resistance according to the value(s) in the table below.
- Standard Resistance:
| Tester Connection | Condition | Specified Condition |
| A30-1 - A39-2 (STP) | Always | Below 1 Ω |
| A30-1 - Body ground | Always | 10 kΩ higher |
| | REPAIR OR REPLACE HARNESS OR CONNECTOR |
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| 6.CHECK HARNESS AND CONNECTOR (STOP LIGHT CONTROL RELAY - BRAKE LIGHT RELAY) |
Disconnect the A39 stop light control relay connector.
Remove the brake light relay from the engine room relay block.
Measure the resistance according to the value(s) in the table below.
- Standard Resistance:
| Tester Connection | Condition | Specified Condition |
| A39-8 (OUT) - Brake light relay terminal 4 | Always | Below 1 Ω |
| A39-8 (OUT) - Body ground | Always | 10 kΩ higher |
| | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
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| 7.CHECK STOP LIGHT CONTROL RELAY |
Remove the stop light control relay with its connector still connected ( ).
Measure the voltage according to the value(s) in the table below.
- Standard Voltage:
| Tester Connection | Switch Condition | Specified Condition |
| A39-6 (+B) - A39-4 (GND) | Always | 11 to 14 V |
| A39-2 (STP) - Body ground |
Stop light switch on
(Brake pedal depressed) | 11 to 14 V |
Stop light switch off
(Brake pedal released) | Below 1 V |
| A39-8 (OUT) - Body ground |
Stop light switch on
(Brake pedal depressed) | 11 to 14 V |
Stop light switch off
(Brake pedal released) | Below 1 V |
| | REPLACE STOP LIGHT CONTROL RELAY ()
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| 8.CHECK HARNESS AND CONNECTOR (BRAKE LIGHT RELAY - BATTERY) |
Remove the brake light relay from the engine room relay block.
Measure the voltage according to the value(s) in the table below.
- Standard Voltage:
| Tester Connection | Switch Condition | Specified Condition |
| Brake light relay terminal 1 - Body ground | Engine switch on (IG) | 11 to 14 V |
| Brake light relay terminal 5 - Body ground | Always |
| | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
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| 9.CHECK HARNESS AND CONNECTOR (BRAKE LIGHT RELAY, STOP LIGHT CONTROL RELAY - MASTER CYLINDER SOLENOID) |
Disconnect the A24 master cylinder solenoid (skid control ECU) connector.
Remove the brake light relay from the engine room relay block.
Disconnect the A39 stop light control relay connector.
Measure the resistance according to the value(s) in the table below.
- Standard Resistance:
| Tester Connection | Condition | Specified Condition |
| Brake light relay terminal 2 - A24-16 (STP0) | Always | Below 1 Ω |
| A39-2 (STP) - A24-45 (STP2) |
| Brake light relay terminal 3 - A24-7 (STP) |
| Brake light relay terminal 2 - Body ground | Always | 10 kΩ higher |
| A39-2 (STP) - Body ground |
| Brake light relay terminal 3 - Body ground |
Result| Result | Proceed to |
OK
(for LHD) | A |
OK
(for RHD) | B |
| NG | C |
| | REPLACE MASTER CYLINDER SOLENOID (SKID CONTROL ECU) ()
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| | REPAIR OR REPLACE HARNESS OR CONNECTOR |
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| A | |
| |
| REPLACE MASTER CYLINDER SOLENOID (SKID CONTROL ECU) ()
|
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| 10.INSPECT STOP LIGHT SWITCH |
Remove the stop light switch ().
Measure the resistance according to the value(s) in the table below.
- Standard Resistance:
| Tester Connection | Switch Condition | Specified Condition |
| 1 - 2 | Pin not pushed | Below 1 Ω |
| Pin pushed | 10 kΩ higher |
| 3 - 4 | Pin not pushed | 10 kΩ higher |
| Pin pushed | Below 1 Ω |
| | REPLACE STOP LIGHT SWITCH ()
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| 11.CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH - BATTERY) |
Disconnect the A30 stop light switch connector.
Measure the voltage according to the value(s) in the table below.
- Standard Voltage:
| Tester Connection | Switch Condition | Specified Condition |
| A30-2 - Body ground | Engine switch on (IG) | 11 to 14 V |
| A30-4 - Body ground | Always |
| | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
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| 12.CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH - ECM) |
Disconnect the A38*1 or A53*2 ECM connector.
Disconnect the A30 stop light switch connector.
Measure the resistance according to the value(s) in the table below.
- Standard Resistance:
for LHD| Tester Connection | Condition | Specified Condition |
| A30-3 - A38-35 (ST1-) | Always | Below 1 Ω |
| A30-1 - A38-36 (STP) |
| A30-1 - Body ground | Always | 10 kΩ higher |
| A30-3 - Body ground |
for RHD| Tester Connection | Condition | Specified Condition |
| A30-3 - A53-35 (ST1-) | Always | Below 1 Ω |
| A30-1 - A53-36 (STP) |
| A30-1 - Body ground | Always | 10 kΩ higher |
| A30-3 - Body ground |
Result| Result | Proceed to |
| OK (1UR-FE) | A |
| OK (3UR-FE) | B |
| NG | C |
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| | REPAIR OR REPLACE HARNESS OR CONNECTOR |
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