C1738

DTC C1738 Open or Short Circuit In Left Front Height Control Solenoid Valve Circuit

CIRCUIT DESCRIPTION

DTC Detection Condition:

The ECU energizes the height control solenoid valve, which opens the valve and leads compressed air to the pneumatic cylinder, thus raising the vehicle height.

When the vehicle height is lowered, the ECU energizes not only the height control solenoid valve but also the exhaust valve which open the valve and discharge the compressed air in the pneumatic cylinder to the atmosphere.

Front and rear height control valves have 2 solenoid valves to control right hand and left hand pneumatic cylinders separately

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

HINT:
- Code C1737/31 corresponds to the right front height control solenoid valve circuit.
- Code C1738/32 corresponds to the left front height control solenoid valve circuit.
- Code C1739/33 corresponds to the right rear height control solenoid valve circuit.
- Code C1740/34 corresponds to the left rear height control solenoid valve circuit.

Once the ECU stores DTC C1737/31, C1738/32, C1739/33, C1740/34 or C1735/35 in memory, the vehicle height control is not carried out until a normal signal is input to the ECU from the height control solenoid valves and exhaust valve.

However, the control is resumed if the ignition switch is turned OFF, then ON again.

Wiring Diagram:

Step 1:

Step 2:

Step 2 (Cont'd) - 3:

Step 4:

Step 5:

INSPECTION PROCEDURE

HINT:
- Proceed with troubleshooting in accordance with the flow chart, regardless of whether or not DTC C1737/31, C1738/32, C1739/33, C1740/34 or C1735/35 is displayed.
- When DTC C1737/31 is displayed, check the right front height control solenoid valve circuit.
- When DTC C1738/32 is displayed, check the left front height control solenoid valve circuit.
- When DTC C1739/33 is displayed, check the right rear height control solenoid valve circuit.
- When DTC C1740/34 is displayed, check the left rear height control solenoid valve circuit.
- When DTC C1735/35 is displayed, check the height control exhaust valve circuit.
- If DTC C1774/74 (power source circuit) is displayed, perform the inspection necessary for DTC C1774/74 first.
- Start the inspection from step 1 in case of using the LEXUS hand-held tester and start from step 2 in case of not using the LEXUS hand-held tester.