Verify +15 VDC is applied to all sensors:
Vehicle Monitor:
- Control Pillar: TB-1, pins 1, 2, or 3 (receivers)
- Auxiliary Pillar: TB-6, pins 1, 2, or 3 (emitters)
Rail Monitor:
- Control Pillar: TB-2, pin 17 (receivers)
- Auxiliary Pillar: TB-6, pin 2 and 3 (emitters)