TM 5-5420-280-23&P
0008 00
Electrical System Troubleshooting (Contd).
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
33. RCU WILL NOT RETRIEVE BRIDGE FROM GAP (R7-H)
Step 1. Check that KY1, KY7, and KY22 hydraulic control valve solenoid LED lights are lit when
action button 2 is depressed.
NOTE
Limit switches KA3 and KA4 work together to stop bridge and
actuate launch boom, moving bridge toward A-frame and stops.
a. If all lights are lit on control valve solenoids, check limit switches KA3 and KA4 to see if
damaged or out of adjustment. Adjust or replace limit switches KA3 and KA4
b. If limit switches KA3 and KA4 are operating and control valve solenoid lights are lit,
refer to malfunction 14 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 solenoids.
b. If connector has 24 volts, replace control valve solenoid or hydraulic control valve. Refer
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, KL-1 buss bar pin 22 for
KY22 control valve solenoid, KL-1 buss bar pin 27 for KA3 limit switch, and KL-1 buss
bar pin 28 for KA4 limit switch. Refer to Electrical System Schematic (WP 0122 00) and
d. Check wire between KL-1 buss bar pin 1 and IQAN-XS connector pin 20. Replace wire if
e. Check wire between KL-1 buss bar pins 7, 22, 27, and 28 and IQAN-XP connector pins
39, 26, 4, and 5. Replace wires if damaged. Refer to WP 0053 00.
END OF TESTING
34. RCU WILL NOT RETRIEVE BRIDGE TO PALLET (R10-H)
Step 1. Check that KY1, KY3, KY7, and KY21 hydraulic control valve solenoid LED lights are lit
when action button 2 is depressed.
NOTE
Limit switch KA8 has two operations, it stops bridge at base of
A-frame and then operates winch to lift bridge up to lock bridge
pins behind channels on A-frame and then stops bridge.
a. If all lights are lit on control valve solenoids, check limit switch KA8 low and KA8 high to
see if damaged or out of adjustment. Adjust low or high or replace limit switch KA8.
b. If limit switch KA8 low and KA8 high is operating and control valve solenoid red light is
lit, refer to malfunction 10 in Hydraulic System Troubleshooting (WP 0010 00).
c. Check operation of IQAN-XP and IQ-XS LED lights. Refer to WP 0004 00 step h.
Change 1