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: RM000001CTQ006X
Title: SUSPENSION CONTROL: ACTIVE HEIGHT CONTROL SUSPENSION: DESCRIPTION (2008 LX570)

DTC

C1766

Height Control Pump Motor Current

DESCRIPTION

In case that the height control has not finished in spite of performing the raise control for a certain period of time, the ECU interrupts the height control.

DTC Code	Detection Condition	Trouble Area
C1766	When the height control pump and motor operates continuously for 135 seconds.	Fluid leakage No. 1 height control valve Suspension control relay Height control pump and motor Clog in the fluid line Suspension control ECU

INSPECTION PROCEDURE

NOTICE:

If the suspension control ECU or height control sensor is replaced, the vehicle height offset calibration must be performed .
When the cargo weight is extremely heavy, this DTC may be stored.

PROCEDURE

1.	INSPECT FOR FLUID LEAK

(a) Inspect for fluid leaks .

2.	PERFORM ACTIVE TEST USING TECHSTREAM (LEVELING VALVE, ACCUMULATOR VALVE AND GATE 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 of the leveling valve solenoid, accumulator valve solenoid and gate 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.
Front Gate Valve	Front gate solenoid valve	ON or OFF	When the Front Gate Valve item of the Active Test is operated, the Front Gate Valve item of the Data List changes to ON/OFF.
Rear Gate Valve	Rear gate solenoid valve	ON or OFF	When the Rear Gate Valve item of the Active Test is operated, the Rear Gate Valve item of the Data List changes to ON/OFF.

OK:

The leveling valve solenoid, accumulator valve solenoid and/or gate valve solenoid operates.

3.	INSPECT SUSPENSION CONTROL RELAY (AHC)

(a) Remove the suspension control relay from the engine room relay block.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
3 - 5	Battery voltage is not applied to terminal 1 and 2	10 kΩ or higher
3 - 5	Battery voltage is applied to terminal 1 and 2	Below 1 Ω

4.	CHECK OPERATION OF HEIGHT CONTROL PUMP AND MOTOR

(a) Remove the height control pump and motor .

(b) Inspect if the compressor is stuck.

(1) Apply battery voltage to the compressor motor and check the operation of the motor.

OK:

Measurement Condition

Specified Condition

Battery positive (+) → Terminal 2

Battery negative (-) → Terminal 1

Motor operates

NOTICE:

Do not allow the motor to operate for 60 seconds or more.

If the height control pump and motor is shorted, locked, or has a similar type of malfunction, a large amount of current will be flowing. Therefore, if the motor does not operate, immediately stop this inspection.

5.	INSPECT 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.