Notes on Intermittents

NOTE ON INTERMETTENTS
As with virtually any electronic system, intermittent failures in the RSS system may be difficult to accurately diagnose. The RSS control module tests for different failures under different vehicle conditions; for this reason, it is often necessary to perform a test drive to repeat the failure and allow a code to set.

If the system maiflinction is not repeated during the test drive, a good description of vehicle behavior may be helpful in locating a "most likely" component or circuit. The symptom diagnosis chart may also be useful in isolating the failure.

Most intermittent problems are caused by faulty electrical connections or wiring. When an intermittent failure is encountered, check suspect circuits for:
^ Poor mating of connector halves or terminals not fully seated in the connector body (backed out).
^ Improperly formed or damaged terminals. All connector terminals in a problem circuit should be carefully reformed to increase contact tension.
^ Poor terminal to wire connection. This requires removing the terminal from the connector body to inspect.

Most failures of the RSS system will allow operation to resume during the ignition cycle in which a failure occurred if the failure conditions are no longer present. Some failures will disable some RSS flinctionality for the entire ignition cycle, even if the fault clears before key-off.

Many fault conditions which result in the displaying of the "SERVICE RIDE CONTROL" message do not cause storage of any RSS fault codes. Among these fault conditions are any problems with the battery, ignition, or ground connections to the RSS controller, along with all associated wiring and flises. Also included are any problems with the Universal Asynchronous Receiver Transmitter (UART) communications interface. Circuits involving these inputs to the RSS control module should be investigated if a complaint of intermittent warning system operation is encountered, particularly if no RSS fault codes are present.

Battery or ignition voltage out-of-range conditions (below (10.0 volts or above 16.0 volts) will disrupt the ability of the controller to log codes and assert the "SERVICE RIDE CONTROL" message. If a voltage out-of-range condition occurs while driving, degraded modes will be employed. Once normal voltage ranges are present at the RSS control module, normal diagnostic operation will resume.

LEVELING SYSTEM FAULTS
Various electrical and pneumatic fault conditions can prevent valid leveling system operation. Although some of the fault conditions will cause storage of corresponding fault codes, none of them will cause a "SERVICE RIDE CONTROL" display.
Therefore, if a complaint of incorrect vehicle leveling operation occurs, always begin the diagnostic procedure by displaying fault codes and repairing any faults which are recorded. If, after all fault codes are addressed and cleared, the leveling system continues to operate incorrectly (or fails to operate), check for pneumatic and/or compressor module problems, as appropriate.