Installation manual

GEM INSTALLATION MANUAL DOCUMENT No. 070906 REV. 1.4
INSIGHT
INSTRUMENT CORP. 16 BOX 122, FORT ERIE, ONTARIO, L2A 5M6
Note: Plan your Installation to include a service loop in the GEM wiring harness to allow for future
adjustments.
Wires for the supplemental features are supplied pre-terminated at the sensor end, but must be
terminated at the instrument end during installation. The D-sub connectors (25 and 37 pin) utilize crimp
pins, see the materials section for recommended tooling.
Some of the D-sub connectors ground pins are shared by multiple wires, use a "pig-tail" style
connection inside the connector shell to accommodate multiple wires connected to a single pin.
Display Power and Ground Wiring Connections
The GEM displays automatically accommodates both 14 and 28 Volt electrical systems. Connect
the “red” power lead to a separate trip-free, re-settable circuit breaker (1 Amp) that receives power
from the avionics bus or aircraft bus.
If the aircraft does not include an Avionics Master switch circuit or bus, we recommend that one be
installed or a separate switch (user provided) to remove power from the Display unit during engine
starts.
Connect the ground wire (black) to a common avionics ground bus (airframe ground).
CAUTION: For upgrade installations (from GEM 602 or 603) where the harness is grounded to the engine
case, disconnect the ground from the engine case and connect the ground wire to the ground bus (airframe
ground). Do not connect to two ground points.
NOTE: Double check the Display ground connection before applying power. Many aircraft have terminal strips
under the instrument panel that will appear to be connected to airframe ground and will even measure to
ground with an ohmmeter. The terminal strips may instead be connected to ground terminated loads such as
landing lights or gear motors. When these loads are activated the voltage on this supposed ground will rise to
full bus voltage (14 or 28V). [Extensive damage may result from improper grounding and is not covered under
warranty.]
Refer to Drawing No. 1200-018.
EGT Probe Wiring
The temperature probes must be wired with the correct polarity. The EGT probes connect to the harness wires
with the yellow jacket. The probe leads and harness wires are color coded (red and yellow) to facilitate correct
polarity. Each wire is marked with the cylinder number.
Slide the wire marker down the wire so it remains with the installation for trouble-shooting. Strip the wires ac-
cording to Drawing No. 8254 and terminate with the crimp-on terminals (provided).
Verify the quality of each crimp with a “sharp” pull on the wire. The terminal should be almost impossible to pull
off when crimped correctly. Harness and probe wire colors should match as in Drawing No. 8254.
NOTE: The ring terminals may be crimped with a “service type” tool, however, AMP part number #47386 is
recommended. Be sure to test each crimp by pulling on the wire to ensure it won’t come out. The most
common installation problems are the result of poor quality termination.