- Stop light switch
- Stop light switch circuit
- ECM
| Last Modified: 11-27-2007 | 1.6 C | |
| Service Category: Engine/Hybrid System | Section: Cruise Control | |
| Model Year: 2008 | Model: LX570 | Doc ID: RM000000ZRE02QX |
| Title: CRUISE CONTROL: CRUISE CONTROL SYSTEM: DESCRIPTION (2008 LX570) | ||
|
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 1 V for 0.5 sec. or more. |
|
WIRING DIAGRAM
INSPECTION PROCEDURE
PROCEDURE
|
1. |
READ VALUE USING TECHSTREAM (STOP LIGHT SWITCH) |
(a) Using the Techstream, 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.
|
|
2. |
INSPECT STOP LIGHT SWITCH |
(a) Remove the stop light switch
.
(b) 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 |
|
|
3. |
CHECK HARNESS AND CONNECTOR (BATTERY - STOP LIGHT SWITCH) |
(a) Disconnect the A30 stop light switch connector.
(b) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
|
Tester Connection |
Switch Condition |
Specified Condition |
|---|---|---|
|
A30-2 - Body ground |
Always |
11 to 14 V |
|
A30-3 - Body ground |
Engine switch on (IG) |
|
|
4. |
CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH - ECM) |
(a) Disconnect the A30 stop light switch connector.
(b) Disconnect the A38 ECM connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
A30-1 - A38-36 (STP) |
Always |
Below 1 Ω |
|
A30-1 - Body ground |
Always |
10 kΩ or higher |
|
A30-4 - A38-35 (ST1-) |
Always |
Below 1 Ω |
|
A30-4 - Body ground |
Always |
10 kΩ or higher |
|
|
|