C1738: OBD-II code C1738 flags the air-suspension exhaust solenoid circuit shorted to ground — the exhaust valve cannot be commanded properly, so the vehicle cannot bleed off pressure.

Symptoms

• The 'Service Ride Control' warning is displayed and the vehicle may sit higher than target ride height on one or more corners.
• The suspension cannot lower itself because the exhaust solenoid drive circuit is shorted to ground.
• Compressor cycling may be reduced because the module cannot complete a normal fill/exhaust cycle.

Common causes

• A chafed exhaust solenoid drive wire touching chassis ground, holding the drive line at 0 V continuously.
• An internally shorted exhaust solenoid coil pulling the drive circuit to ground.
• Water intrusion into the exhaust solenoid connector causing a short from the drive wire to a ground pin.

What to do?

Disconnect the exhaust solenoid and check the drive wire for continuity to ground with the connector unplugged — there should be no continuity. Measure the solenoid coil resistance. Replace the solenoid or repair the wiring; if wiring and coil are good, replace the suspension control module.