TM 5-5420-280-23&P
0008 00
Electrical System Troubleshooting (Contd).
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
40. RCU WILL NOT RETRIEVE LOWER BRIDGE HALF (R13-A)
Step 1. Check that KY1, KY5, and KY7 hydraulic control valve solenoid LED lights are lit when
action button 2 is depressed.
NOTE
Limit switch KA1 stops lower bridge half and limit switch KA2
switches rear pin wheel drive to front pin wheel drive.
a. If all lights are lit on control valve solenoids, check limit switch KA1 and KA2 to see if
damaged or out of adjustment. Adjust or replace limit switch KA1 and KA2. Refer to
b. If limit switches KA1 and KA2 are 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 5 for KY5 control valve solenoid, KL-1 buss bar pin 7 for
KY7 control valve solenoid, KL-1 pin 25 for KA1 limit switch, and KL-1 buss bar pin 26
for KA2 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 pins 20. Replace wire if
damaged. Refer to WP 0053 00.
e. Check wires between KL-1 buss bar pins 5, 7, 25, and 26 and IQAN-XP connector pins 38,
39, 2, and 3. Replace wires if damaged. Refer to WP 0053 00.
END OF TESTING