Dispenser powers up but will not pump
Start with: DMEX
- Confirm dispenser number
- Check DMEX control power
- Verify hook signal changes
- Check E-stop / reset chain
- Trace relay output to pump contactor
Card reader offline / no communication
Start with: LVDD
- Confirm dispenser number
- Locate LVDD module for that dispenser
- Identify motherboard group
- Check low-voltage input/output path
- Inspect data/video/card reader connections
All dispensers down
Start with: Site shutdown chain
- Emergency stop stations
- Reset logic
- Tank monitor shutdown
- Main dispenser-control power
Intermittent dispenser fault
Start with: LVDD first, then DMEX
- Check communication path stability
- Inspect module-to-board connections
- Verify DMEX relay behavior
- Move outward to field wiring if needed
Reset not working
Start with: DMEX
- Check shutdown chain state
- Verify reset circuit path
- Check control power and module connections
Lighting problem
Start with: Lighting sensor / manager
- Check LMZ10SEN1 sensor
- Check control power
- Check contactor outputs and wiring