Code S032 - Speed-Sensitive Steering Short Across Load: Description

SSS short across load errors are detected via an analog feedback signal obtained from a low side sense resistor. The voltage is sensed off of this resistor to allow small Pulse Width Modulation (PWM) duty cycle adjustments to be made due to battery voltage and valve resistance fluctuations.

If the desired current differs from the actual feedback current by more than 0.5 percent, then a command change of ±1.1 percent is issued every 20 milliseconds until the command and feedback come within a range of less than 0.5 percent. This is accomplished by turning a switch on and off at 125 Hz with a duty cycle that varies based on vehicle speed and feedback current between 5 percent and 95 percent duty cycle.

This PWM causes the driver to experience less steering assist as duty cycle increases with vehicle speed, resulting in more current flow to the SSS solenoid. The RSS module monitors this analog feedback very frequently to look for abrupt changes.

Since a short across load is potentially destructive to the high side and low side circuitry in the RSS module, an error detection yields a 0 percent duty cycle very rapidly, and a cool-down time is allotted before another attempt is made to drive the SSS solenoid. Multiple attempts are required to supply filtering to avoid false errors from being detected.

If a specific number of consecutive errors occur, the SSS PWM is set to 0 percent duty cycle for the remainder of the ignition cycle. The default mode for the SSS valve is full assist with 0 percent duty cycle which yields no current.