Table 4-2. Unit Troubleshooting (Con't).
TEST OR INSPECTION
With semitrailer lights turned on, disconnect wiring harness connector (8) and measure voltage
between wiring harness connector and other bare metal on semitrailer.
If measurement is not approximately 24 volts, replace wiring harness (para 4-14) or repair
Check all connectors (4), lamp sockets (6), and lamps (5) for corrosion and damage.
If connectors (4), sockets (6), or lamps (5) are corroded, scrape and clean off corrosion.
If connectors (4) are damaged, replace (para 4-15). If sockets (6) or lamps (5) are damaged,
ONE OR MORE LAMPS (BUT NOT ALL) WILL NOT LIGHT.
Check for burned out lamp (5) and loose connectors (4).
If connector (4) is loose, tighten.
Check for loose or broken light assembly (7).
If light assembly (7) is loose, tighten.
Check for corroded and broken lamp contact and socket (6).
If contact or socket (6) is corroded, scrape and clean.