S028

CODE S028 RR DAMPER SOLENOID VALVE SHORT ACROSS LOAD












TEST CONDITIONS:
The RSS control module monitors the damper solenoid circuit on both sides of the solenoid valve during the on and PWM portions of the commanded signal. The module expects to see the high-side feedback high and low-side feedback low within the first 1 mS of the on period or during a PWM low state. It also expects to see the high-side low and the low-side high during a PWM high state as well as the high-side low and 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 low for three consecutive samples (samples taken at five second intervals) during the on period, a code is set.

ACTION TAKEN:
The RSS control module will stop driving the solenoid within the first 1 mS sample in which a fault is sensed either during the commanded on period or a commanded PWM high state. The RSS control module will then attempt driving the solenoid again, and then 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 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 form 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.

Shorts across solenoid 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 across the solenoid is destructive to the high-side circuitry, and 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 occurs, all four dampers are de-energized for the remainder of the ignition cycle. The default mode for the damper solenoid is closed or non- energized.

NOTES ON FAULT TREE:
[1] Refer to notes on intermittents.
[2] A short to voltage in circuit 1118 or a short to ground in circuit 1119 may damage the windings in the solenoid and create an open.
[3] 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.