TM 5-5420-280-23&P
0008 00
Electrical System Troubleshooting (Contd).
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
4. RCU WILL NOT EXTEND BRIDGE TO OPERATING WIDTH (L2-H)
Step 1. Check that all four fastening rods have been removed.
Remove fastening rods. Refer to TM 5-5420-280-10.
Step 2. Check that KY1 and KY13 hydraulic control valve solenoid LED lights are lit when action
button 1 is depressed.
a. If both lights are lit on control valve solenoids. Refer to malfunction 4 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 3. Check to see if only one of the control valve solenoid LED lights is lit.
a. If only one light is lit, check for 24 volts at control valve solenoid without a light.
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 13 for KY13 control valve solenoid. Refer to Electrical
System Schematic (WP 0122 00) and repair or replace wires (WP 0053 00).
d. Check wires between KL-1 buss bar pin 1 and 13 and IQAN-XS connector pins 20 and 21.
Replace wires if damaged WP 0053 00.
END OF TESTING
5. RCU WILL NOT RETRACT WINCH WIRE ROPE (L3-A)
Step 1. Check if winch electrical harness, control cable, or power supply cable are loose or damaged.
If loose or damaged, connect or replace winch electrical harness, control cable, or power
supply cable. Refer to WP 0065 00, Electrical System Schematic WP 0122 00 and Winch
Electronic Box Schematic WP 0124 00.
Step 2. Check if power supply cable is suppling power to winch electronic box.
a. If power supply cable has no power, check if fuse is blown. Replace 8 Amp fuse.
b. If fuse is good, repair or replace power supply cable. Refer to WP 0065 00, Electrical
System Schematic WP 0122 00 and Winch Electronic Box Schematic WP 0124 00.
c. Check for voltage at winch relays AD2, AD3, and AD4.
Step 3. Check if rope loop sensor light is lit when action button 1 is depressed.
a. If light is not lit, check for loose connector on rope-loop sensor.
b. If light is lit, check if rope loop sensor is out of adjustment or damaged and adjust or
replace rope loop sensor. Refer to WP 0064 00.
Step 4. Check if winch system has hydraulic pressure to winch control block, refer to
malfunction 5 in Hydraulic System Troubleshooting (WP 0010 00).
Step 5. Check that KY1, and KY21 hydraulic control valve solenoid LED lights are lit when action
button 1 is depressed.
NOTE
Limit switch KA5 stops winch cable when upper bridge half is
lifted to its up position.
a. If all lights are lit on control valve solenoids, check limit switch KA5 to see if damaged or
out of adjustment. Adjust or replace limit switch KA5. Refer to WP 0056 00.
b. Check operation of IQAN-XP and IQAN-XS LED lights. Refer to WP 0004 00 step h.
c. If limit switch KA5 is operating and control valve solenoid lights are lit, refer to
malfunction 5 Hydraulic System Troubleshooting (WP 0010 00).
Change 1
