Mark

The Stall Warning system on a 767 warns the crew of an impending stall by shaking the control column.

There are two stall warning systems. If they both sense the stall, a control yoke pusher (nudger on the 767) physically pushes the yoke forward.

A flight crew notification on the EICAS status page will show "WARN ELEX" if the stall warning system has a failure.
  
     
  
We normally see this when the IRS's are not aligned, as the stall system cards need valid IRS data.
We had an aircraft with this warning after the IRS's were up.

The left system was not testing. The test should give you a shaker. When we tested both systems at the same time, the left shaker would start working and we'd get a nudger (with hydraulics on).

In the forward accessory compartment we checked the wiring on the left shaker..... they fell right out with a slight tug. That would explain why the left shaker would start working with the right already on. Vibration from the right helped the left have continuity.
  
     
  
It might be explained in the FIM or Fault Isolation Manual, but the schematics give no hint that the card must see continuity through the shaker coil.

The schematic will show how the card provides a ground to activate the shaker. It doesn't show how continuity is monitored. I can only guess that the card wants to see 28VDC on pin 34. The coil is not "working" (or shaking), so the 28VDC is present on pin 34. (If the shaker was activated.... all the voltage would be dropped across the coil)