Suspension Control ( Automatic - Electronic Level )

DTC 34 - Leveling Solenoid Valve Circuit

CIRCUIT DESCRIPTION

DTC Detecting Condition:

The suspension control ECU opens the height control valve to lead the compressed air to the pneumatic cylinder and raise the vehicle height.

When the vehicle height is lowered, the suspension control ECU opens the height control valve to store the compressed air in the low pressure tank temporarily, and then operates the exhaust solenoid valve to release the compressed air to the outside.

Further, the height control solenoid valve (gate solenoid valve) opens and closes the passage between the right and left pneumatic cylinder.

The height control valve is on the low pressure tank and consists of 3 valves in total, leveling solenoid valve, gate solenoid valve and tank solenoid valve.

The leveling solenoid valve opens and close the passage between the compressor and the pneumatic cylinder.

The gate solenoid valve opens and close the passage between the right and left pneumatic cylinder. The tank solenoid valve opens and closes the passage between pneumatic cylinder and the low pressure tank.

The exhaust solenoid valve is on the compressor unit and has only one valve.

HINT:
- Once ECU stores DTC C1733/33, C1734/34, C1735/35 or C1744/44 in the memory, the vehicle height control is not carried out until a normal signal is input to ECU from the height control solenoid valves and the exhaust solenoid valve.
However, the control is resumed if the ignition switch is turned OFF, then ON again.
- Malfunction in the gate solenoid valve and the leveling solenoid valve:
The height control operation is suspended, and the height control indicator lamp dose not change by operating the height control switch.
- Malfunction in the exhaust solenoid valve:
The vehicle height is lowered to the normal height within 30 sec., and then the height control operation is suspended. The height control indicator lamp "N" comes on or blinks, and that of "HI" and "LO" do not come on by operating the height control switch "UP" and "DOWN".
- Abnormality of the tank solenoid valve:
Although the height control is still possible, the lowering speed may be slower.

Wiring Diagram:

Step 1:

Step 2:

Step 3:

INSPECTION PROCEDURE

HINT:
- Proceed to troubleshooting following the flow chart, regardless of whether or not DTC C1733/33, C1734/34, C1735/35 or C1744/44 is displayed.
- If DTC C1761/61 (ECU malfunction) and/or C1774/74 (power source circuit) is displayed, perform the inspection necessary for DTC C1761/61 and/or C1774/74 first.
(If DTC C1761/61 and C1774/74 are output at the same time, perform the inspection necessary for DTC C1774/74 first.)
- Start the inspection from step 1 in case of using the hand-held tester and start from step 2 in case of not using the hand-held tester
- Since the exhaust solenoid valve cannot be tested in ACTIVE TEST, start the inspection from step 2.