TM 5-5420-280-23&P
0008 00
Electrical System Troubleshooting (Contd).
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
41. RCU WILL NOT RETRIEVE LOWER BRIDGE HALF (R17-H)
Step 1. Check that KY1 and KY7 hydraulic control valve solenoid LED lights are lit when action
button 2 is depressed.
NOTE
Limit switch KA3 stops lower bridge half before lowering secondary
boom.
a. If all lights are lit on control valve solenoids, check limit switch KA3 for damage or out of
adjustment. Adjust or replace limit switch KA3. Refer to WP 0056 00.
b. If limit switch KA3 is operating and control valve solenoid lights are lit, refer to
malfunction 10 in Hydraulic System Troubleshooting (WP 0010 00).
c. Check operation of IQAN-XP and IQAN-XS LED lights. Refer to WP 0004 00 step h.
Step 2. Check to see if one or more control valve solenoid LED lights are out when action button 2
is depressed.
a. If light is out, check for 24 volts at control valve solenoid.
b. If connector has 24 volts, replace control valve solenoid or hydraulic control valve. Refer
to WP 0075 00.
c. If connector has no voltage, check wires at KL-1 buss bar pin 1 for KY1 control valve
solenoid, KL-1 buss bar pin 7 for KY7 control valve solenoid, and KL-1 buss bar pin 27
for KA3 limit switch. Refer to Electrical System Schematic (WP 0122 00) and repair or
replace wires (WP 0053 00).
d. Check wire between KL-1 buss bar pin 1 and IQAN-XS connector pin 20. Replace wire if
damaged. Refer to WP 0053 00.
e. Check wires between KL-1 buss bar pins 7and 27 and IQAN-XP connector pins 39 and 4.
Replace wires if damaged. Refer to WP 0053 00.
END OF TESTING
42. RCU WILL NOT LOWER SECONDARY BOOM (R14-H)
Step 1. Check that KY1 and KY14 hydraulic control valve solenoid LED lights are lit when action
button 2 is depressed.
a. If both lights are lit on control valve solenoids, refer to malfunction 11 in Hydraulic
System Troubleshooting (WP 0010 00).
b. Check operation of IQAN-XP and IQAN-XS LED lights. Refer to WP 0004 00 step h.
Step 2. Check to see if one or more control valve solenoid LED lights are out when action button 2
is depressed.
a. If light is out, check for 24 volts at control valve solenoid.
b. If connector has 24 volts, replace control valve solenoid or hydraulic control valve. Refer
to WP 0075 00.
c. If connector has no voltage, check wires at KL-1 buss bar pin 1 for KY1 control valve
solenoid and KL-1 buss bar pin 14 for KY14 control valve solenoid. Refer to Electrical
System Schematic (WP 0122 00) and repair or replace wires (WP 0053 00).
d. Check wire between KL-1 buss bar pin 1 and IQAN-XS connector pin 20. Replace wire if
damaged. Refer to WP 0053 00.
e. Check wire between KL-1 buss bar pin 14 and IQAN-XP connector pin 32. Replace wire if
damaged. Refer to WP 0053 00.
END OF TESTING