Garnet SEELEVEL II 709-LL Manual page 21

The diagnostics can be used to check the wiring and the
senders:
1. If a short circuit is showing, disconnect the senders one at a
time at the sender location. If the short circuit indication goes
away when a sender is removed, then that sender is bad. If all
the senders are removed but a short circuit still shows, then
the wiring may be shorted. Disconnect the sender wire at the
display, the short indication should go away. If it doesn't, the
display is bad.
2. If an open circuit for all the senders is showing, it is most likely
a wiring open circuit or display failure, since it is unlikely that all
three senders are bad. Try shorting the wiring together at the
display, the display should indicate a short circuit. If it doesn't,
the display is bad. If it does, then remove that connection and
short the wires together at the sender locations. If no short
circuit is shown, then the wiring is open. If the display does
show a short circuit, then the senders must be bad.
3. If a single sender is showing an open, try shorting the wiring
together right at that sender. If a short now shows, the sender
is bad or not wired properly. If no short circuit shows on the
display, the wiring to that sender is open.
To review the sender diagnostics:
1. The sender diagnostics can be reviewed periodically to check
for any degradation of the tank senders. If a sender appears
to be malfunctioning, reviewing the diagnostics should be the
first step in the troubleshooting process. Note that there are
no diagnostics for the battery voltage.
2. There are two diagnostics for the senders: the signal power,
and the sender height.
a.
b. The sender height is the number of receive segments
709-LL Manual
The signal power is an indication of how much signal is
being transmitted through the tank wall and picked up
by the receive part of the sender. If the signal power is
too low, it can indicate a sender which is detached from
the tank, excessive buildup on the inside of the tank, bad
wiring to the sender, low battery voltage, or a defective
sender. Typical signal power should be 50% - 60%. The
minimum signal power for proper operation is 20%.
present in the sender. To determine the length of the
sender, multiply the calibration by 1.5 (ES sender) or
1.0 (JS sender) to get the length in inches. The senders
always auto calibrate to the length that they are cut, so
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