TM 5-5420-280-23&P
0008 00
Electrical System Troubleshooting (Contd).
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
16. RCU WILL NOT LIFT LAUNCH BOOM TO COUPLING POSITION (L14-A) (Contd)
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 17 for KY17 control valve solenoid, and KL-1 buss bar
pins 34, 35, and 48 for potentiometer JR2. Refer to Electrical System Schematic
d. Check wires between KL-1 buss bar pins 1, 17, 34, 35, and 48 and IQAN-XP connector
pins 20, 34, 15, 17, and 1. Replace wires if damaged. Refer to WP 0053 00.
END OF TESTING
17. RCU WILL NOT LOWER SECONDARY BOOM (L13-H)
Step 1. Check that KY1 and KY15 hydraulic control valve solenoid LED lights are lit when action
button 1 is depressed.
NOTE
Limit switch KA 7 stops secondary boom in bridge coupling
position.
a. If both lights are lit on control valve solenoids, check limit switch KA7 to see if damaged
or out of adjustment. Adjust or replace limit switch KA7. Refer to WP 0056 00.
b. If limit switch KA7 is operating and control valve solenoid lights are lit, refer to
malfunction 11 Hydraulic System Troubleshooting. Refer to 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 no lights are lit when action button 1 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 15 for KY15 control valve solenoid, and KL-1 pin 31 for KA7
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 pins 1 and 31 and IQAN-XS connector pins 20 and 24.
Replace wires if damaged. Refer to WP 0053 00.
e. Check wire between KL-1 buss bar pin 15 and IQAN-XP connector pin 33. Replace wire if
damaged. Refer to WP 0053 00.
END OF TESTING
