SUSPENSION CONTROL: ACTIVE HEIGHT CONTROL SUSPENSION: DESCRIPTION (2008 LX570)

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Last Modified: 11-27-2007		1.6 C
Service Category: Suspension	Section: Suspension Control System
Model Year: 2008	Model: LX570	Doc ID: RM000001CUA006X
Title: SUSPENSION CONTROL: ACTIVE HEIGHT CONTROL SUSPENSION: DESCRIPTION (2008 LX570)

DTC

C1764

Abnormal Leveling Valve Oil Pressure

DTC

C1765

Abnormal Accumulator Valve Oil Pressure

DESCRIPTION

The solenoid valve is located in the No. 1 height control valve. When the vehicle height is adjusted, the fluid line is opened or closed according to the signal from the suspension control ECU. If the height control pump and motor activates when the fluid line is closed due to the solenoid valve malfunctioning, the solenoid valve being stuck, or foreign matter clogging the fluid line, fluid pressure increases abnormally. When this problem with the fluid pressure is detected, DTC C1764 and/or DTC C1765 is stored.

DTC Code	Detection Condition	Trouble Area
C1764	When the height control pump and motor activates and the fluid pressure is 18.5 MPa (188.6 kgf/cm², 2683 psi) or more for 0.3 seconds.	No. 1 height control valve (Each solenoid valve is stuck) Clog in the fluid line Suspension control ECU
C1765	When the height control pump and motor activates and the fluid pressure is 18.5 MPa (188.6 kgf/cm², 2683 psi) or more for 0.3 seconds.	No. 1 height control valve (Each solenoid valve is stuck) Clog in the fluid line Suspension control ECU

INSPECTION PROCEDURE

NOTICE:

Before performing troubleshooting, inspect the connectors of related circuits.

If the suspension control ECU or height control sensor is replaced, the vehicle height offset calibration must be performed .

PROCEDURE

1.	PERFORM ACTIVE TEST USING TECHSTREAM (EACH LEVELING VALVE AND ACCUMULATOR VALVE)

(a) Turn the engine switch off.

(b) Connect the Techstream to the DLC3.

(d) Enter the following menus: Chassis / AHC / Active Test.

(e) Check the operation sound of the solenoid or vibration of the leveling valve solenoid and accumulator valve solenoid when operating the solenoid with the Techstream.

AHC

Tester Display	Test Part	Control Range	Diagnostic Note
Front Right Height Solenoid	Front height control solenoid valve RH	ON or OFF	Operation of the solenoid can be heard.
Front Left Height Solenoid	Front height control solenoid valve LH	ON or OFF	Operation of the solenoid can be heard.
Rear Right Height Solenoid	Rear height control solenoid valve RH	ON or OFF	Operation of the solenoid can be heard.
Rear Left Height Solenoid	Rear height control solenoid valve LH	ON or OFF	Operation of the solenoid can be heard.
Accumulator Valve	Accumulator solenoid valve	ON or OFF	Operation of the solenoid can be heard.

OK:

The operation sound of the solenoid should be heard or the vibration of the leveling valve solenoid or accumulator valve solenoid should be felt.

2.	CHECK FLUID LINE

(a) Check if the fluid line is clogged.

HINT:

Check if the fluid line that connects the height control pump and motor and No. 1 height control valve is clogged. If it is not clogged, there probably is foreign matter clogging the interior of the No. 1 height control valve.
Follow the removal and installation procedures for each part, as all parts need to be removed.