Q. My water level monitor is not working, one or more lights are out.
A. 1. Check that you are using the correct bulb and that the bulb is working.
2. Check that there are no cuts, etc. in the connecting cables.
3. Check that connectors fit properly.
4. Make sure that the display module is grounded properly.
5. If you are installing a new display module on an old truck, verify that both the
display module and the truck have the same ground.
Q. I have checked all the above and the unit is still not working properly.
A. Disconnect the cable between the display module, the sensor, and the ground
connection (there will be a disconnect 3' from the bottom of the display module). The
four level lights should be out. If you have a five light unit, the refill light will be
flashing. Connect a jumper between the chassis ground and the nylon plug terminal,
one pin at a time. For every pin grounded you should see one light operational. If one or
more of the bulbs do not light, there is a problem with the display module.
Pin order for Connector: Yellow: Top left
Blue: Top right
Black: Bottom right
White: Bottom left
Q. The display module has been checked as stated above, but the unit is still not
A. With the display module still disconnected remove the sensor from the tank. Check
the cable for cuts. etc. Loosen the compression fitting and remove the stainless steel
tube. Wipe down the four probes to remove any debris that may have adhered. If
necessary use fine, detergent free, steel wool to further clean the probes. Wipe
down the stainless steel tube and reassemble the probe. Reinstall in the tank and reconnect
to the display module.
Q. The display module has been checked and the sensor has been cleaned but the unit
is still not working correctly.
A. Ensure that the truck has a full tank of water. Disconnect the plug and ground wire
between the display module and the sensor. Using an ohm meter perform a
continuity check from the sensor connector to the chassis ground for each probe. Each
probe should register an approximate 0 to 15k ohm resistance reading on the meter.
Q. The tank is empty and one or more level lights are lit.
A. This usually indicates that a bridge of water is occurring in the sensor. With the
sensor disconnected from the display module, loosen the compression fitting, remove
the stainless steel tube and check that the cable ties are properly tightened. If a cable
tie is missing or loose, a bridge will occur. There should be one spacer above the second
probe and another at the bottom of the sensor approximately one inch from the bottom of the
Another possibility is a faulty component in the display module. Disconnect the
from the display module. If the light stays on, there is a faulty component in the
display module. If the light goes out, remove the sensor from the tank, clean the sensor,
cut the cable ties, and check the continuity to ground for each probe (NOTE: all cable
ties must be replaced or spacers may cause drain to clog.) Be sure to pull the probe
away from the bundle when checking for continuity.
Q. How do I clean the Series 500 stainless steel sensor?
A. Disconnect the sensor from the control box. Loosen the compression fitting, remove
any debris that may have adhered. If necessary use fine, detergent free, steel wool to
further clean the probes. Wipe down the stainless steel tube and reassemble the probe.
Reinstall in the tank and reconnect to the control box.