TM 1-2840-252-23-3
G-73
INSULATION/VOLTAGE CHECK EXPANDED INSTRUCTIONS
Refer to numbered steps in figure 159.
Step 1.
Check the resistance between the DECU case at the ground strap and airframe ground using a 4-
wire configuration. Limit is < 50Ω.
Step 2..
With PL1 and PL3 (figure 201) disconnected, check the resista ce between each harness PL1 and
n
PL3 connector socket (except PL1 -Y, PL1-t and PL3-N) and airframe ground. For PL1 sockets Z
and u (figure 202), and PL3 sockets R and m, limit is < 2Ω. For PL3 sockets v and GG, limit is >
1000Ω. For all others, limit is > 1MΩ.
Step 3.
With PL1 and PL3 disconnected, check the resistance between the pin pairs listed in the table
below at harness PL1 and PL3 connector sockets. Limit in each case is > MΩ
1
Step 4.
With PL1 and PL3 disconnected. turn on airframe su ply and emergency supply. Check voltage
p
of the airframe supply at harness PL1 connector sockets Y and Z, and t andu. Limit is 16-30V.
Check voltage of the emergency supply at harness PL3 connector sockets N andm. Limit is
16 -30V.
Step 9.
Refer to manufacturer's procedure for diagnosing and replacing ground strap. See instructions for
fault check defined by original procedure being followed.
Step 11.
Refer to manufacturer's procedure for diagnosing and replacing harness or component.
See
instructions for fault check defined by original procedure being followed.
Step 13.
Refer to manufacturer's procedure for diagnosing and replacing harness or component.
See
instructions for fault check defined by original procedure being followed.
Step 15.
Refer to manufacturer's procedure for diagnosing and replacing harness or component.
See
instructions for fault check defined by original procedure being followed.
RESISTANCE-CHECK SUMMARY - STEP 1
Connection
Measurement Locations
Resistance
Limits (m Ω)
Ground Strap
DECU case and airframe ground
<50
G-172
