Installation manual

GEM INSTALLATION MANUAL DOCUMENT No. 070906 REV. 1.4
INSIGHT
INSTRUMENT CORP. 21 BOX 122, FORT ERIE, ONTARIO, L2A 5M6
Symptom: One or more columns will not illuminate.
Cause: Check the probe connections, the display will blank columns with poor EGT and CHT connections.
Columns 5 and 6 shouldn’t illuminate on a 4 cylinder engine. Check the probe diagnostic page.
Symptom: No EGT in one or more columns.
Cause: Errors in harness wiring. Visually check probe connections and polarity. Check the probe diagnostic
page or measure the resistance of the lead wire manually. It is approximately 1 ohm per foot. Take extreme
care to not damage the connector terminals with the meter probes.
Symptom: No CHT in one or more columns.
Cause: Errors in harness wiring. Visually check probe connections and polarity. Check the probe diagnostic page
or measure the resistance of the lead wire manually. It is approximately 1 ohm per foot. Take extreme care to not
damage the connector terminals with the meter probes.
Symptom: No CHT in one or more columns.
Cause: Faulty probe. Visually check probe connections and polarity. Check the probe diagnostic page or
measure the resistance of the probe manually. It is approximately one ohm. Take extreme care to not damage
the connector terminals with the meter probes.
Symptom: Display goes out during engine start.
Cause: Voltage transient or over voltage condition. The display should not be turned on during engine
start. An Avionics Master or separate power switch should be installed to apply power to the display.
Symptom: Display is unstable.
Cause: Noisy or defective magneto or ignition harness. Check operation on left and right magnetos.
The temperature should rise slowly and may stabilize slightly or completely on one or the other
magneto. Single magneto operation will pinpoint the problem to one ignition harness, unless both
are faulty. Verify that the probe wires and GEM series system harness are isolated from the ignition
harness. If necessary, repair or replace the faulty ignition harness to eliminate ignition related
interference.
Symptom: Display is unstable.
Cause: Magneto ungrounded or defective P-lead. Check ignition harness for proper shielding,
grounding, and loose spark plug caps. Check magnetos for proper grounding or evidence of arcing.
Disconnect magneto P-leads one at a time. If this eliminates or reduces the problem, replace the P-
lead. A faulty ignition harness will typically cause all EGT readings to “dance” up and down. The GEM
series Display will detect this type of fault long before standard test methods, thus eliminating the
potential of more serious problems.
Symptom: Display is unstable.
Cause: Noisy or defective alternator, defective generator or faulty ground connection. Try operation
with alternator or generator off. Alternator related interference may indicate faulty commutator.