Dtc P0571 Brake Switch A Circuit
DESCRIPTION
WIRING DIAGRAM
INSPECTION PROCEDURE
READ VALUE USING INTELLIGENT TESTER (STOP LIGHT SWITCH)
INSPECT STOP LIGHT SWITCH
CHECK HARNESS AND CONNECTOR (BATTERY - STOP LIGHT SWITCH)
CHECK ENGINE TYPE
CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH - ECM)
CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH - ECM)
DTC P0571 Brake Switch "A" Circuit
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 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 | When the voltage of the STP terminal and the ST1- terminal of the ECM is below than 1 V for 0.5 second. or more. | Stop light switch
Stop light switch circuit
ECM
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WIRING DIAGRAM
INSPECTION PROCEDURE
| 1.READ VALUE USING INTELLIGENT TESTER (STOP LIGHT SWITCH) |
Using the intelligent tester, read the Data List ().
Cruise Control| 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.
Result| Result | Proceed to |
OK
(for 1GR-FE) | A |
OK
(for 1UR-FE) | B |
OK
(for 3UR-FE) | C |
OK
(for 1VD-FTV) | D |
| NG | E |
| 2.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 pushed | 10 kΩ or higher |
| Pin not pushed | Below 1 Ω |
| 3 - 4 | Pin pushed | Below 1 Ω |
| Pin not pushed | 10 kΩ or higher |
Result| Result | Proceed to |
| OK | A |
| NG (for LHD) | B |
| NG (for RHD) | C |
| | REPLACE STOP LIGHT SWITCH ()
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| | REPLACE STOP LIGHT SWITCH ()
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| 3.CHECK HARNESS AND CONNECTOR (BATTERY - STOP LIGHT SWITCH) |
Disconnect the A30 stop light switch connector.
Measure the voltage according to the value(s) in the table below.
- Standard Voltage:
| Tester Connection | Condition | Specified Condition |
| A30-2 - Body ground | Always | 11 to 14 V |
| A30-4 - Body ground | Ignition switch ON |
| | REPAIR OR REPLACE HARNESS OR CONNECTOR |
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Check the engine type.
Engine Type| Engine type | Proceed to |
| for 1GR-FE, 1UR-FE, 3UR-FE, 1VD-FTV (w/o DPF) | A |
| for 1VD-FTV (w/ DPF) | B |
| 5.CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH - ECM) |
Disconnect the A30 stop light switch connector.
Disconnect the A38*1 or A52*2 ECM connector.
Measure the resistance according to the value(s) in the table below.
- Standard Resistance:
for LHD| Tester Connection | Condition | Specified Condition |
| A30-1 - A38-36 (STP) | Always | Below 1 Ω |
| A30-1 - Body ground | Always | 10 kΩ or higher |
| A30-3 - A38-35 (ST1-) | Always | Below 1 Ω |
| A30-3 - Body ground | Always | 10 kΩ or higher |
for RHD| Tester Connection | Condition | Specified Condition |
| A30-1 - A52-36 (STP) | Always | Below 1 Ω |
| A30-1 - Body ground | Always | 10 kΩ or higher |
| A30-3 - A52-35 (ST1-) | Always | Below 1 Ω |
| A30-3 - Body ground | Always | 10 kΩ or higher |
Result| Result | Proceed to |
OK
(for 1GR-FE) | A |
OK
(for 1UR-FE) | B |
OK
(for 3UR-FE) | C |
OK
(for 1VD-FTV, w/o DPF) | D |
| NG | E |
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| | REPAIR OR REPLACE HARNESS OR CONNECTOR |
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| 6.CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH - ECM) |
Disconnect the A30 stop light switch connector.
Disconnect the A38*1 or A52*2 ECM connector.
Measure the resistance according to the value(s) in the table below.
- Standard Resistance:
for LHD| Tester Connection | Condition | Specified Condition |
| A30-1 - A38-13 (STP) | Always | Below 1 Ω |
| A30-1 - Body ground | Always | 10 kΩ or higher |
| A30-3 - A38-35 (ST1-) | Always | Below 1 Ω |
| A30-3 - Body ground | Always | 10 kΩ or higher |
for RHD| Tester Connection | Condition | Specified Condition |
| A30-1 - A52-13 (STP) | Always | Below 1 Ω |
| A30-1 - Body ground | Always | 10 kΩ or higher |
| A30-3 - A52-35 (ST1-) | Always | Below 1 Ω |
| A30-3 - Body ground | Always | 10 kΩ or higher |
| | REPAIR OR REPLACE HARNESS OR CONNECTOR |
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