TM 9-2330-294-14
Table 4-3. Troubleshooting SemitrailerContinued
MALFUNCTION
TINT OR INSPECTION
CORRECTIVE ACTION
2. ONE OR MORE LAMPS WILL NOT LIGHTContinued
all ground attaching screws and washers to insure metallic continuity between ground
wire and frame.
Step 4. Check for damaged retractable clearance light assembly.
Replace damaged retractable clearance light assembly (para 4-20).
3. ALL SERVICE LIGHT (LEFT OR RIGHT SIDE) FAIL TO LIGHT
Step 1. Check for broken cable. Make open circuit test (para 4-15a ).
Repair if accessible (para 4-28). Notify direct support personnel to replace wires
buried in body of main harness.
Step 2. Check for defective circuit breaker.
Replace circuit breaker (para 4-16).
SUSPENSION SYSTEM
4. SEMITRAILER SAGS TO ONE SIDE
Check for loose bolts on walking beam.
Tighten bolts and nuts.
5. EXCESSIVELY-WORN, SCUFFED OR CUPPED TIRES
NOTE
Mild cupping is normal or non-driving tires. Reverse tires periodically to balance wear,
Step 1. Check for loose wheel bearings.
Adjust wheel bearings (para 4-60e ).
Step 2. Check for deformed rim or wheel.
Replace wheel (para 4-59).
Step 3. Check for out of round brake drum.
Notify direct support maintenance personnel for repair and/or replacement unit.
Step 4. Check air suspension system.
Refer to table 4-4.
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
BRAKE AIR SYSTEM
1 . NO RESPONSE FROM ANY SEMITRAILER BRAKE WHEN BRAKE PEDAL IN
TOWING VEHICLE IS DEPRESSED
Step 1. Check for excessive drum to lining clearance on all wheels (para 4-30b ).
Adjust brakes (para 4-30b ).
Step 2. Check for damaged service air line.
Replace damaged air line (para 4-39).
2. NO BRAKE RESPONSE ON FRONT TANDEM ONLY, OR ON REAR TANDEM ONLY
Step 1. Visually inspect service air line to emergency relay valve on axle tandem without brakes
for dents or breaks. Loosen fitting on line at emergency relay valve and depress towing
brake pedal. Air will escape when pedal is depressed if line is clear.
Replace damaged or plugged air line (para 4-39).
Step 2. Visually inspect line between semitrailer reservoir and relay valve on affected axle for dents
or breaks. Cautiously loosen fitting at relay valve. Air should escape; no air indicates
plugged line.
Replace damaged or plugged air line (para 4-39).
4-9
