Air Suspension System (W/O AVS)

SUSPENSION CONTROL: AIR SUSPENSION SYSTEM (w/o AVS): C1747: Leveling Solenoid Valve Circuit Malfunction

DTC C1747 - Leveling Solenoid Valve Circuit Malfunction

DESCRIPTION

The suspension control ECU opens the leveling solenoid valve (No. 2 height control valve) to lead the compressed air to the height control cylinder (pneumatic cylinder) and to raise the vehicle height.
The No. 2 height control valve consists of a leveling solenoid valve and a gate solenoid valve.
The leveling solenoid valve opens and closes the passage between the compressor and the height control cylinder (pneumatic cylinder).





HINT:
- Once the ECU stores DTC C1747 in the memory, the vehicle height control is suspended until a normal signal is input to the ECU from the height control solenoid valves. However, control is resumed if the ignition switch is turned off, then to ON again.
- Malfunction in the leveling solenoid valve:
The height control operation is suspended, and the height control indicator light does not change by operating the height control switch.

WIRING DIAGRAM





INSPECTION PROCEDURE

HINT:
- If DTC C1781 (ECU malfunction) and/or C1782 (power source circuit) is displayed, perform the inspection necessary for DTC C1781 C1781 and/or C1782 C1782 first.
- If DTC C1781 and the C1782 are output at the same time, perform the inspection necessary for DTC C1782 first.

PROCEDURE

1. PERFORM ACTIVE TEST USING TECHSTREAM (REAR LEVELING SOLENOID)
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON, and turn the Techstream main switch on.
(c) Enter the following menus: Chassis / Air suspension / Active Test.

Air Suspension





OK:
Operation of solenoid (clicking sound) can be heard

Result





C -- USE SIMULATION METHOD TO CHECK
B -- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE
A -- Continue to next step.

2. INSPECT NO. 2 HEIGHT CONTROL VALVE SUB-ASSEMBLY (LEVELING SOLENOID VALVE)
(a) Turn the ignition switch off.





(b) Disconnect Q4 solenoid valve connector.
(c) Measure the resistance according to the value(s) in the table below.

Standard Resistance:





(d) Connect the battery positive (+) lead to terminal 1 and the negative (-) lead to terminal 2 of the solenoid valve connector. Then check that the valve makes an operating sound.
OK:
Operation of solenoid (clicking sound) can be heard

NG -- REPLACE NO. 2 HEIGHT CONTROL VALVE SUB-ASSEMBLY
OK -- Continue to next step.

3. CHECK HARNESS AND CONNECTOR (LEVELING SOLENOID VALVE - ECU AND BODY GROUND)





(a) Disconnect the O19 ECU connector.
(b) Measure the resistance according to the value(s) in the table below.

Standard Resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE SUSPENSION CONTROL ECU