Installation manual

GEM INSTALLATION MANUAL DOCUMENT No. 070906 REV. 1.4
INSIGHT
INSTRUMENT CORP. 17 BOX 122, FORT ERIE, ONTARIO, L2A 5M6
CHT Probe Wiring
The CHT temperature probes must be wired with the correct polarity. The CHT probes connect to the harness
wires with the black jacket. The probe leads and harness wires are color coded (red and white) 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.
Terminate with the crimp-on ring 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 according to Drawing No. 8254. Insulate and bundle as
discussed below.
Routing the EGT/CHT/TIT Wiring Harness (P1 and P3)
It is essential to match the cylinder numbers on all the probes to display the proper information to the pilot.
The probe/harness connections should be insulated with the high temperature fiberglass sleeves provided and
routed away from high temperature areas, e.g. exhaust stacks, turbochargers, etc.
The probe wires must not be tied in with ignition, alternator or cabin heater ignition wires because of potential
errors in temperature readings.
All wires should be bundled and tied with nylon wire ties or lacing cord and attached to the airframe to prevent
damage from vibration and wind buffeting.
The probe wiring harnesses are made of special alloy wire that must not be substituted or extended with
cop- per wire.
Do not cut the harness too short. Leave a service loop to allow for service and maintenance or in case
adjustments are required in the harness routing.
The power and ground wires are copper and may be extended if necessary, but NOT the thermocouple wires.
When the installation is complete all wires should be secured using wire ties and carefully checked for
interference, rubbing or chafing with flight control cables, or other moving parts.
A Ferrite RF filter should be installed surrounding the Thermocouple wires and located close to the GEM.
This is supplied by Insight on new harnesses, and are available from Insight to add on to existing installations.
Connecting and Routing the P2 Harnesses
The P2 harness connects to the D-sub connector (either 25 or 37 pins) on the back of the GEM. This harness
carries the electrical signals for all the GEM's supplementary functions such as Fuel Flow, Oil Temperature and
pressure, RS-232 communications, etc.
Route the wiring harness away from any high temperatures and high energy sources and be sure to leave a
service loop to allow adjustments and ease maintenance. Route the thermocouple wires in the P2 harness
through the Ferrite RF filter (on the P1 harness) as shown in Drawings No. 8252 and 8253.