C1737

CIRCUIT DESCRIPTION
The Electronic Leveling Control (ELC) exhaust solenoid valve is controlled (switched ON/OFF) by the Continuously Variable Road Sensing Suspension (CVRSS) control module. The control module provides a low-side drive (switched to ground) whenever exhaust activity is required and during a "head-relief" sequence which occurs at compressor start-up. This drive output from the CVRSS control module is also continually monitored to determine if the voltage level agrees with the commanded state.

CONDITION FOR SETTING THE CODE "CURRENT"
The CVRSS control module measures a feedback voltage at pin "C14" greater than a preset threshold during an exhaust solenoid valve ON-state.

ACTIONS TAKEN WHEN CODE SETS
^ ALL rear leveling activity for the remainder of the Ignition cycle will be disabled.
^ "SERVICE RIDE CONTROL" message will be display.

CONDITION FOR CODE TURNING "HISTORY"
The CVRSS control module no longer senses a high voltage at pin "C14", when the exhaust solenoid valve is in an ON-state.

HOW TO CLEAR THE CODE
^ Use the scan tool.
^ Use the On-Board diagnostic "CLEAR RSS CODES" feature.

TEST DESCRIPTION
The numbers below refer to step numbers on the diagnostic table.
2. Checks for an internal short h1 the exhaust solenoid valve.
3. Checks for a short to battery on circuit 320.

DIAGNOSTIC AIDS
This fault condition is detectable only when the exhaust solenoid valve output is commanded to the ON-state, which occurs before each compressor start-up and whenever a downward correction is necessary. The CVRSS control module expects to see a low voltage during the ON-state.

Only electrical problems with the exhaust solenoid valve are flagged. Pneumatic blockage problems do not set a code, but the CVRSS control module shuts off the exhaust function ii no progress is made or if excessive run times occur. Recovery is nor attempted until ignition is cycled OFF and ON.

Important: Check for disconnected or damaged air lines.