TM 5-5420-280-23&P
0008 00
Electrical System Troubleshooting (Contd).
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
45. RCU WILL NOT LOWER LIFTING CYLINDERS (R2-H)
Step 1. Check that KY1 and KY16 hydraulic control valve solenoid LED lights are lit when action
button 2 is depressed.
NOTE
Pressure switch KF1 stops lower lifting cylinders when they are
fully retrieved.
a. If both lights are lit on control valve solenoids, check pressure switch KF1 to see if
damaged or out of adjustment. Adjust or replace pressure switch KF1 on manifold. Refer
to WP 0056 00.
b. If pressure switch KF1 is operating and control valve solenoids are lit, refer to
malfunction 15 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 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 16 for KY16 control valve solenoid, and KL-1 buss bar pin 33
for KF1 pressure 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 33 and IQAN-XS connector pins 20 and 22.
Replace wire if damaged. Refer to WP 0053 00.
e. Check wire between KL-1 buss bar pin 16 and IQAN-XP connector pin 35. Replace wire if
damaged. Refer to WP 0053 00.
END OF TESTING
46. RCU WILL NOT RETRIEVE LOWER BRIDGE HALF (R17-H)
Step 1. Check that KY1 and KY5 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 10 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 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 5 for KY5 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 5 and IQAN-XP connector pin 38. Replace wire if
damaged. Refer to WP 0053 00.
END OF TESTING