Road Sensing Suspension (RSS)

CIRCUIT DESCRIPTION
The RSS module adjusts the steering effort to a desired level as a function of vehicle speed by controlling the amount of current to the steering control solenoid. Current is controlled by switching the solenoid's high-side circuitry to battery voltage through solid-state circuitry using a pulse-width modulated (PWM) signal. This PWM signal varies based upon the vehicle speed and the feedback current. Thus, as vehicle speed increases, so does the current through the SSS solenoid which in turn provides less steering assist.

Faults are detected by the RSS module monitoring a high-side and a low-side feedback signal which are connected to the solenoid's drive and return line, respectively. Since a short to voltage is potentially destructive to the low-side circuitry in the RSS module, a fault detection results in the SSS solenoid being de-energized very rapidly and being allowed to cool down before another attempt is made to drive the solenoid. The default mode for the SSS solenoid is full assist (no current flow).

RS0030 WILL SET WHEN
The RSS module senses the high-side drive high during an "OFF" state and one of the following conditions for three consecutive samples:
1. The high-side drive high and a low current reading is made during an "ON" state.
2. The high-side drive high and a high current reading is made during an "ON" state.

ACTION TAKEN
The RSS module will stop driving the solenoid immediately once the fault is detected. The module will then attempt to drive the solenoid again once the vehicle speed equals 0 and 5 seconds have passed since the last retry. During the retry, the feedback signals are resensed. If the fault is not present, the RSS 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, the solenoid is de-energized for the remainder of the ignition cycle, a code is set, and the "SERVICE RIDE CONTROL" message is displayed.

RS0030 WILL GO "HISTORY" WHEN
The RSS module senses the high-side drive low and reads a normal current reading when the solenoid is "OFF" plus senses the high-side drive high and reads a normal current reading when the solenoid is "ON."

NOTES ON FAULT TREE
1. Refer to INTERMITTENT S AND POOR CONNECTIONS. Diagnostic Aids
2. Refer to Clearing Diagnostic Trouble Codes. Clearing Diagnostic Trouble Codes
3. Replace steering system fluid filter whenever the SSS solenoid is replaced.

DIAGNOSTIC AIDS
SSS diagnostics must he performed at 0 vehicle speed.
History codes are used to help diagnose intermittent fault conditions and do not necessarily indicate a faulty RSS module. The RSS module itself is a reliable component and is not likely the cause of the malfunction. Most system complaints are linked to faulty wiring and connectors and, occasionally, components. Performing a thorough inspection of all related wiring and connectors pertaining to the history code stored will reduce diagnostic time and prevent unnecessary part replacement. If the problem is intermittent, try performing the tests shown while "wiggling" wiring and connectors. This can often cause the malfunction to appear. Check for poor connections at both the RSS module and the related components. These could cause an open, short, or an intermittent malfunction. Refer to Intermittents And Poor Connections. Diagnostic Aids

IMPORTANT
^ Do not backprobe sensors, dampers, electronic leveling control (ECL) connectors, or SSS connectors.
^ When all diagnosis and repairs are complete, clear codes and verify operation.