There are 4 kinds of alarm will make the pump stop and the white light blink or solid on.

1. Emergency stop

There are two emergency buttons

2. Intensifier over load 

For 50,000PSI, 0.012 inch orifice, it usually cycles 66 times in the minute.

3. Water pressure too low.

water pressure must be above 40 PSI. This sensor is linked to the PLC via the line 0100. Picture attached.  This signal can be bypass through disconnecting line 0100. 

4. Electrical current over load

This one is linked to PLC via the line 0010.  Picture attached. This signal can be bypass through connecting 0010 and 225 together.