FloTech FT520 Manuel D'instructions page 4

FINDING A DEFECTIVE SENSOR IN A OPTIC SYSTEM WITH NO ONBOARD
MONITOR:
A) This test requires two FT520 testers or a rack monitor to energize the optic system. One
tester is used to energize the string of sensors and one tester is used to find the defect.
B) Connect the five wire test lead set to one of the testers.
C) Remove the optic socket faceplate.
D) Connect the RED test lead to pin 8. Connect the BLACK test lead to pin 10. Connect the
YELLOW test lead to pin 4. Connect the ORANGE test lead to pin 6.
OPTION: Use the FT521, FT522 or FT523 API compatible test plug to make a quick
connection to the socket front. This test plug is similar to the plug used at the load rack.
If the monitor output to the socket is good the Sonalert will beep and the sensor ok light
E) Turn on the first tester.
F) The yellow LED should light, the green LED should be lit and the Sonalert should report
with an intermittent beeping signal. This is a GOOD sensor system. If the green LED is
not lit and no tone is heard the sensor system is defective. Go to step G.
G) Take the second FT520 tester and connect the two-wire test lead set (probe and clip lead).
And turn the tester on. With the two-wire test lead set the tester acts as a pulse detector. It
will sound a tone if a pulse is detected and not sound a tone if no pulse is detected.
H) Remove the sensor housing caps.
I) Starting with sensor in compartment one, clip the black test lead to the sensor housing and
push the red test probe into the yellow crimp connection going into the probe. The tester
should report a tone. If no tone is heard then check the continuity of the cable from the
socket to sensor compartment one. Replace the defective wire and retest. If the tester
sounds a tone the push the red probe into the orange wire connection on sensor
compartment one. If a tone is sounded the sensor is good. Move on to the next sensor in
the string and repeat the test. If no tone is sounded the sensor is defective. Replace the
sensor and retest the system.
Note: If the trailer is wired in a non-standard configuration or truck and trailer
J) Test for pulses into (yellow) each sensor and out (orange) of each sensor. The problem can
be found where no pulse is found.
K) Look for bad crimp connection by pulling on each crimp connection. Most frequent
problems are bad crimp connection. When replacing these crimp connections add some
RTV sealant into each crimp. This will protect the connection from moisture.
L) After the defective sensor or wire connection is found and repaired, retest the system at the
socket. Contact your local FloTech / Bayco Distributor for quality replacement parts.
TESTING A 5 WIRE OPTIC SYSTEM WITH ONBOARD MONITOR:
A) Check onboard monitor status LEDs. The power LED should be lit. If the power LED is
not lit check for 12 VDC on the power terminal. Normally in the upper left hand corner of
the monitor box. The monitor must be powered to continue test.
Rev: January 2010
configurations refer to the trailer wiring schematic.
will flash.
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