Table 4-2. Unit Troubleshooting (Con't).
TEST OR INSPECTION
Check for broken cable.
Disconnect wiring harness connector (8) at inoperative lamp (5) and measure continuity between
wiring harness connector and bulb contact.
Turn semitrailer lights on and measure voltage between wiring harness connector (8) and good
If measurement is not approximately 24 volts, replace wiring harness or repair wiring harness
DIM OR FLICKERING LIGHTS.
Check for loose ground wire in electrical receptacle connector at front of semitrailer.
If ground wire is loose, tighten.
BRAKES WILL NOT RELEASE.
Check for restrictions in air lines and hoses.
If air line or hoses have a restriction, repair (para 4-28).
Apply tractor brakes and release. Emergency relay valve should vent airbrake chamber (10) air
through exhaust port when tractor brakes are released.
If airbrake chamber (10) air is not vented when tractor brakes are released, replace