Table 4-2. Unit Troubleshooting (cont'd)
TEST OR INSPECTION
Step 2. Check for loose or defective wiring components in resistor box (XM1063) or voltage
converter box (M129A4).
If wiring is defective or loose, repair wire.
If components are loose or damaged, repair or replace components.
If malfunction is not corrected, proceed to step 3 (XM1063) or step 6 (M129A4).
Step 3. Check resistor contact points.
Clean resistor contact points.
If resistor contracts are clean, proceed to step 4.
Step 4. Check resistors for rated ohms marked on resistors, using multimeter (refer
to wiring diagram page 4-58).
Replace cracked, chipped or defective resistor (para. 4-23).
If resistors are in good condition, proceed to step 5.
Step 5. Remove resistor box cover and check connections on circuit boards (1).
Make sure nut (2) and washer (3) are tight at each connection.
If nut and washer are loose, tighten them.
If connections are tight, proceed to step 7.
M129A4 Registration Numbers NX0RKB and Subsequent LED lighting
system voltage converter boxes no longer contain fuses/circuit breakers.
Step 6. Check voltage converter circuit breakers (M129A4).
Replace defective circuit breaker.
If circuit breakers are functioning properly, proceed to step 7.
M129A4 Registration Number NX0RKB and Subsequent semitrailer are equipped
with LED lighting systems. Lamps can not be replaced.
Step 7. Checkfordefectivelightassembly.