REV. A February 21, 2011 7 Manual Number 9017211
SECTION 3 INSTALLATION PROCEDURES
3.1 GENERAL INFORMATION
This section contains interconnect diagrams, mounting dimensions and other information pertaining to
the installation of the MD41 series ACU. After installation of cabling and before installation of the
equipment, ensure that power is applied only to the pins specified in the interconnect diagram.
3.2 UNPACKING AND INSPECTING EQUIPMENT
When unpacking this equipment, make a visual inspection for evidence of any damage that may have
incurred during shipment. The following parts should be included:
a. GPS ACU – MCI P/N MD41-151X series
b. J1 Connector Kit (25 pin) – MCI P/N 7014517
c. Installation Manual – MCI P/N 9017211
3.3 CABLE HARNESS
The MD41 cable harness should be made using 24 AWG wire or larger for all connections. Construct the
cable harness with regards to the instructions below and using the Connector Pinout of Figure 3.3,
Schematic Pinout of Table 3.3, and Wiring Diagram of Figure 3.5.
Refer to Section 2: Pre-Installation Considerations in regards to routing precautions.
3.3.1 LIGHTING CONTROL
Button backlighting (pin 5) is powered (5vdc, 14vdc, or 28vdc) from the aircraft’s panel
lighting bus. This will allow manual dimming control of the button brightness using the
aircraft’s panel lighting control dimmer.
There are three options for annunciation brightness control. The annunciations options can
be configured in the following ways:
•Full bright when active
oconnect aircraft power (same as pin 13 input) to pin 6
•Manual control using the aircraft’s panel lighting control
oconnect the aircraft lighting bus power output (same as pin 5 input) to pin 6
o(not available for aircraft with 5V lighting bus)
•Automatically dimming using the internal photocell of the unit
oconnect pin 23 (“Annun Bright/Dim Output”) to pin 6
3.3.2 POWER AND SIGNALS
Wire aircraft power and aircraft ground according to the associated ACU pins in the Pinout
Diagram. Annunciation signals should be wired from the appropriate system inputs and
outputs to the associated ACU pins in the Pinout Diagram.
3.3.3 HARNESS VERIFICATION
With the MD41 ACU disconnected, turn on the avionics master switch and use an ohm-meter
to verify that aircraft power and panel lighting bus power is on the appropriate pin(s) with
appropriate voltage. Also verify that aircraft ground is applied to the appropriate pins.
