Pretrip Inspection and Daily Maintenance 27.5 Check the web retractor for function and damage. This could cause an accident leading to property damage, serious personal injury, or death. 27.6 Check the mounting bolts for tightness and tighten any that are loose. 30. Make sure that both the electric horn and the air horn work. Then check the wiper and washer con- trol. During cold weather, check the operation of the heater and defroster controls. 28. Check the cab interior for loose items and secure or remove them. These devices must be in good working order for safe vehicle operation. If they are not working, re- pair them before trip departure. 29.
Start the engine and make sure the oil-pressure and air-pressure warning systems are working. When the engine is started, oil-pressure and air- pressure warnings will come on until the oil pres- sure rises above a preset minimum and the air pressure in both the primary and secondary air res- ervoir systems goes above 64 to 76 psi (441 to 524 kPa). If the air pressure in both systems is above 64 to 76 psi (441 to 524 kPa) when the engine is started, test the low pressure warning system by lowering the pressure to below this range or until the warning system comes on. 31. Check the operation of the backup alarm if so equipped. 32. Check the operation of all gauge lights and interior lights.
Turn on the headlights, dash lights, and four-way flashers and leave them on. Check the operation of the dome light. If the warning systems do not come on when the ignition is turned on, repair the systems. If any of the gauge bulbs, the switch panel label bulb, the dome light bulb, or the right- and left-turn indicator bulbs are not working, replace them. 33. Make sure all of the lights are working. WARNING Be sure the brake lights, taillights, side marker lights, headlights, signal lights, and clearance and identification lights are working and are clean. Test the high and low beams of the headlights.
Failure to repair the engine shutdown/warning sys- tem could result in the engine shutting down sud- denly, without warning, during vehicle operation. 9.15