*Refreshing this page at any point will restart the troubleshooting guide.
First, please reference the manual for the sensor in question. Each sensor has unique requirements for gear pitch and speed; and will be referenced throughout the troubleshooting process. This guide assumes that the device is properly configured to accept a sinking input.
Manuals
INDUCTIVE PROXIMITY SENSORS (PSAxB)
PSAC - 3-WIRE INDUCTIVE PROXIMITY SENSOR WITH CURRENT SINK OUTPUT
Verify that the unit is being powered
Red Lion proximity sensors require DC power.
PSA1B and PSA2B: 5-30VDC
All others: 10-30VDC
Is the sensor powered properly? 
Correct the power wiring.
Did correcting the power resolve the issue?
Verify that the sensing gear is made of a metal material.
Red Lion's Proximity sensors require a metal gear to detect movement.
Is the gear made of metal?
Replace the gear with one made of metal, or replace the sensor with one that can detect this gear.
Verify that the target is the correct size.
The proximity sensor will only sense items that are at least the same size as the sensor face. There must also be a gap between the targets (gear teeth) greater than or equal to the size of the target. In the case of the PSAC, the small metallic dot in the center of the unit is the sensor.
Is the target large enough?
Replace the target with one that has the correct size, or replace the sensor with one that can sense the existing target.
Verify the air-gap between the sensor and the target.
Red Lion's proximity sensors have varying air-gap requirements, refer to the sensor manual for specifications
*note that a standard credit card is 0.03" thick
Is the air-gap correct?
Correct the air-gap.
Did correcting the air-gap the issue?
Verify that the target is moving at the correct speed.
Red Lion's proximity sensors have varying maximum speeds at which they will function, refer to the sensor manual for specifications
Is the target moving at the correct speed?
Replace the gear, sensor, or monitoring device to achieve a working system.
Verify the output voltage and frequency.
PSA1B and PSA2B: Connect a 3.9K ohm resistor between the signal and common. Use an oscilloscope between signal and common to verify the output voltage and frequency.
All others: Connect a 7.8K ohm resistor between the signal line and the positive side of the power supply. Use an oscilloscope between signal and common to verify the output voltage and frequency.
Is the pickup outputting a signal?
It sounds like a bad sensor.
It sounds like a bad meter.
Please contact Technical Support.
Call us on the toll-free Tech Line: 877-432-9908 or the Support button on the lower right to fill out a contact form.
Congratulations, you have resolved the issue.
Disclaimer
It is the customer's responsibility to review the advice provided herein and its applicability to the system. Red Lion makes no representation about specific knowledge of the customer's system or the specific performance of the system. Red Lion is not responsible for any damage to equipment or connected systems. The use of this document is at your own risk. Red Lion standard product warranty applies.
Red Lion Technical Support
If you have any questions or trouble contact Red Lion Technical Support by clicking here or calling 1-877-432-9908.
For more information: http://www.redlion.net/support/policies-statements/warranty-statement