S026

CODE S026 RR DAMPER SOLENOID VALVE SHORT TO GROUND









TEST CONDITIONS:
The RSS control module monitors the damper solenoid valve during the on and PWM portions of the commanded signal. The module expects to see the high-side feedback low and the low-side feedback high within the first 1 mS of the on period or during a PWM high state. It also expects to see the high-side high and the low- side low during a PWM low state as well as the high-side low and the low-side low during the rest of the on period.

FAULT CONDITIONS:
If the RSS control module sees the high-side feedback high and the low-side feedback high for three consecutive samples (samples taken at five second intervals) during the on period or during a PWM high state, a code is set.

If the RSS control module sees the high-side feedback low and the low-side feedback high for three consecutive samples (samples taken at five second intervals) during the 5 to 15 mS portion of the on period, a code is set.

ACTION TAKEN:
The RSS control module will stop driving the solenoid within the first I mS sample in which a fault is sensed during the commanded on period or during a commanded PWM high state. The RSS control module will then wait 5 seconds, attempt driving the solenoid again, and sense the feedback lines. If the fault is not present, the RSS control module resumes normal operation. Otherwise it will repeat the 'stop-wait-retry-sense" sequence. A software counter is incremented for each fault observed or decremented for each fault not observed. If the counter reaches three counts at any time, a code is set and the solenoid is de-energized for the remainder of the ignition cycle.

DESCRIPTION:
To produce a soft damper setting, the damper's high-side is switched to battery voltage to allow the solenoid to move to the open position. After this initial pull-in, the high-side is then pulse width modulated to hold the valve in the open state while reducing current draw. Finally, the high-side is removed from battery voltage to place the solenoid into a closed position which produces a firm damper setting. The damper's soft and firm settings toggle based on various road conditions in order to provide optimal ride and handling.

Solenoid short to ground errors are detected by a high-side and a low-side feedback signal connected to the damper drive and damper return line, respectively. The RSS control module monitors these feedback lines through all possible states (ON, OFF, PWM high, and PWM low). Since a short to ground is destructive to the high-side circuitry, an error detection results in the solenoid being de-energized very rapidly and being allowed to cool down before another attempt is made to drive the solenoid. Multiple attempts are made to avoid false errors, and if a specific number of consecutive errors occur, all four dampers are de-energized for the remainder of the ignition cycle. The default mode for the damper solenoid is closed or nonenergized.

NOTES ON FAULT TREE:
[1] Refer to notes on intermittents.
[2] Refer to clearing codes.

IMPORTANT:
^ DO NOT BACKPROBE SENSORS, DAMPERS, OR ELC / RSS CONNECTORS.
^ WHEN ALL DIAGNOSIS AND REPAIRS ARE COMPLETE, CLEAR CODES AND VERIFY OPERATION.