I could be wrong on this,but it sounds like the above mentioned,ETC system failure mode,(Rpm guard w/default throttle)in this mode the throttle plate control is disabled,due to the loss of throttle position,or other major ETC system fault and that will put vehicle in (limp mode position),maximum allowed RPM is determined based on pedal position (RPM GUARD)if the RPM exceeds this limit,spark and fuel are used to bring the RPM below the limit,the wrench light and mil are turned on in this mode,hope this helps any. Z