C1735

CIRCUIT DESCRIPTION
The Electronic Leveling Control (ELC) compressor is switched ON and OFF via a compressor relay which is controlled by the CVRSS control module. The control module circuitry provides a switched path to ground (low-side drive) whenever compressor activity is required. This drive circuit 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 sees a high voltage at pin "C15" during a compressor ON state.

ACTIONS TAKEN WHEN CODE SETS
The compressor relay output drive is disabled for the remainder of the ignition cycle.

CONDITION FOR CODE TURNING "HISTORY"
The CVRSS control module no longer senses a high voltage at pin "C15" while the compressor relay output drive 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 open in the compressor relay.
3. Checks to see if circuit 321 is shorted to voltage.

DIAGNOSTIC AIDS
This fault condition is detectable only when the compressor relay output is commanded to the ON state, which occurs during the Air Replenishment Cycle (ARC) and whenever an upward correction is necessary. The control module expects to see a low voltage during the ON-state.

Only electrical problems with the compressor relay coil circuit are flagged. Compressor motor problems and pneumatic leakage problems do not set a code, but the CVRSS control module shuts the compressor relay off if there is no progress, or if excessive run times occur. Recovery is not attempted until ignition is cycled OFF, then ON.