AB60F AUTOMATIC TRANSMISSION / TRANSAXLE: AUTOMATIC TRANSMISSION SYSTEM: DESCRIPTION (2008 LX570)

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Last Modified: 11-27-2007		1.6 C
Service Category: Drivetrain	Section: Automatic Transmission/Transaxle
Model Year: 2008	Model: LX570	Doc ID: RM000000W88071X
Title: AB60F AUTOMATIC TRANSMISSION / TRANSAXLE: AUTOMATIC TRANSMISSION SYSTEM: DESCRIPTION (2008 LX570)

DTC

P0724

Brake Switch "B" Circuit High

DESCRIPTION

The purpose of this circuit is to prevent the engine from stalling while driving in the lock-up condition when the brakes are suddenly applied.

When the brake pedal is depressed, this switch sends a signal to the ECM. Then the ECM cancels the operation of the lock-up clutch while braking is in progress.

DTC Code	DTC Detection Condition	Trouble Area
P0724	The stop light switch remains on even when the vehicle is driven in a STOP (less than 3 km/h (2 mph)) and GO (30 km/h (19 mph) or more) pattern 5 times (2-trip detection logic).	Short in stop light switch signal circuit Stop light switch assembly ECM

MONITOR DESCRIPTION

This DTC indicates that the stop light switch remains on. When the stop light switch remains on during "stop and go" driving, the ECM interprets this as a fault in the stop light switch, the MIL comes on and the ECM stores the DTC. The vehicle must stop (less than 3 km/h (2 mph)) and go (30 km/h (19 mph) or more) 5 times for 2 driving cycles in order to detect a malfunction.

MONITOR STRATEGY

Related DTCs	P0724: Stop light switch/Range check/Rationality
Required sensors/Components	Stop light switch, Vehicle speed sensor
Frequency of operation	Continuous
Duration	GO and STOP 5 times
MIL operation	2 driving cycles
Sequence of operation	None

TYPICAL ENABLING CONDITIONS

The stop light switch remains on during GO and STOP 5 times.

GO and STOP is defined as follows

The monitor will run whenever the following DTCs are not stored	None
Battery voltage	8 V or higher
Engine switch	On (IG)
Starter	OFF
GO: (Vehicle speed is 30 km/h (18.65 mph) or more)	Once
STOP: (Vehicle speed is less than 3 km/h (1.86 mph))	Once

TYPICAL MALFUNCTION THRESHOLDS

Stop light switch status

Stuck on

WIRING DIAGRAM

INSPECTION PROCEDURE

1. DATA LIST

HINT:

Using the Techstream to read the Data List allows the values or states of switches, sensors, actuators and other items to be read without removing any parts. This non-intrusive inspection can be very useful because intermittent conditions or signals may be discovered before parts or wiring is disturbed. Reading the Data List information early in troubleshooting is one way to save diagnostic time.

NOTICE:

In the table below, the values listed under "Normal Condition" are reference values. Do not depend solely on these reference values when deciding whether a part is faulty or not.

(a) Warm up the engine.

(b) Turn the engine switch off.

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

(e) Turn the Techstream on.

(f) Enter the following menus: Powertrain / Engine and ECT / Data List.

(g) According to the display on the Techstream, read the Data List.

Engine and ECT

Tester Display

Measurement Item/Range

Normal Condition

Diagnostic Note

Stop Light Switch

Stop light switch status/

ON or OFF

Brake pedal:

Depressed: ON
Released: OFF

PROCEDURE

1.	INSPECT STOP LIGHT SWITCH ASSEMBLY

(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 not pushed	Below 1 Ω
3 - 4	Pin pushed	Below 1 Ω
1 - 2	Pin pushed	10 kΩ or higher
3 - 4	Pin not pushed	10 kΩ or higher

2.	CHECK HARNESS AND CONNECTOR (BATTERY - ECM)

(a) Disconnect the A38 ECM connector.

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
A38-36 (STP) - Body ground	Brake pedal depressed	11 to 14 V
A38-36 (STP) - Body ground	Brake pedal released	Below 1 V