EA3-x NTC 0x0AF(0) Inverter Independent Signals Too Low

Nexteer Confidential

NTC Overview
NTC 0x0AF.0 Inverter Independent Signals Too Low

Description:

SF049A Loss of Assist Manager tries to avoid system shutdown when safe sensor redundancy is still in tact.  However, customers want to prevent EPS from operating when issues occur repeatedly across ignition cycles.  Nexteer’s strategy is to provide NTCs for each issue to be tracked.

Diagnostic Overview:
Input signal IvtrIdptSig_Cnt_u08 represents the currently active number of Inverters.  When the number of independent signals is equal to or less than a calibration in LoaMgr, the fault status is set instantly to Failed.  LoaMgr can react instantly because the function providing the input signal is expected to debounce before dropping to a lower value.

Typical Fault Response: F3 Notification Only
The diagnostic is set to an F3.  The fault is intended to produce not immediate change in system behavior.  Its purpose is to allow disabling of EPS at the beginning of the Nth ignition cycle.  

Probable Sources (Most to Least Probable):

• •This fault should never get used in single-inverter EA3 programs because the IvtrIdptSig_Cnt_u08 input port of LoaMgr will remain disconnected.  There is no upstream function to send this signal into LoaMgr. 

• •Fault may be active because the threshold calibration value is set too high.  For a single-inverter design, threshold cal should be zero.  For a dual-inverter design, threshold cal should be zero or one. 

• •Fault may be active because LoaMgr input port was not stubbed out with the correct Initial Value.  Should be stubbed with a value of 2.