Inspection of the Cab

Gen5Cas DM Ch 23.01.01
  1. Push the reset button on the dash-mounted air intake restriction indicator, if equipped.

    2. Note: The low-air warning buzzer only works when the park brake is released. The low-air warning buzzer is silenced when the park brake is set.

    Note: The Electronic Air Processing unit (EAPU) measures the air processed by the compressor and regenerates the air dryer as needed. During normal operation, the EAPU, generally once per fill cycle, regenerates the air dryer (purge) using system air. During high use, the EAPU may not use air for dryer regeneration and will have to complete multiple regenerations (purges) later. This may lead to purging noises while the vehicle is idle. These purges are part of normal operation and ensure air quality.

  2. With the keyswitch in the OFF position, check the air-pressure warning system.
    1. If not previously drained, drain the air reservoirs using moderate brake applications until pressure in both reservoirs is less than 70 psi (483 kPa).
    2. Turn the keyswitch to the ON position. The ICU completes a full gauge sweep and bulb check, and a low-air warning buzzer activates. Ensure the low air pressure lamp (BRAKE AIR) remains illuminated.
  3. Check air governor cut-in and cut-out pressures.
    1. Start the engine and ensure the BRAKE AIR lamp goes out and the buzzer deactivates when pressure reaches approximately 70 psi (483 kPa) in both air reservoirs.

      For vehicles with an EAPU, cut out is approximately 141 psi (972 kPa).

    2. With the engine idling, apply the brake pedal several times. For vehicles with an EAPU, cut-in is approximately 123 psi (848 kPa).
  4. Check air pressure build-up time.
    1. With the air system fully charged, make one full brake application and note the air pressure reading on the primary air gauge.
    2. Further reduce air pressure using moderate brake applications, then run the engine at governed rpm.
    3. Note the time that the pressure reaches the previously noted reading on the primary air gauge, then note the time that the air pressure reaches cut-out pressure.
    4. If it takes longer than 30 seconds to reach cut-out pressure after the primary air gauge passes the previously noted pressure (noted after one full brake application), eliminate any leaks or replace the air compressor before operating the vehicle.
  5. Check air leakage in the system.
    1. With the parking brake applied, the transmission in neutral, and the air system fully charged, release the service brakes and shut down the engine.
    2. Wait one minute and note the air pressure drop in psi (kPa) per minute from the primary air reservoir.

      If the pressure drop exceeds the limits shown in Table., eliminate any leaks before operating the vehicle.

  6. Check the air pressure reserve.

    With the engine off, make one full brake application and observe the pressure drop on the primary air gauge. If pressure drops more than 25 psi (172 kPa), eliminate any leaks before operating the vehicle.

    Table 1, Maximum Allowable Air Leakage

    Maximum Allowable Air Leakage

    Description

    Pressure Drop:

    psi (kPa) Per Minute

    Released

    Applied

    Truck or Tractor Only

    2 (14)

    3 (21)

    Truck or Tractor w/Single Trailer

    3 (21)

    4 (28)

    Truck or Tractor w/Two Trailers

    5 (34)

    6 (41)

      Table 1, Maximum Allowable Air Leakage

      1. Warning: When cleaning windshields and windows, always stand on the ground or on a secure ladder or platform. Use a long-handled window cleaner. Do not use the cab steps, tires, fenders, fuel tanks, engine, or under-hood components to access the windshield or windows. Doing so could cause a fall and result in an injury.

    1. Inspect the mirrors, window glass, and windshield for cracks or other damage.
    2. Ensure that the horn, windshield wipers, and windshield washers are operating properly. These devices must be in good working order for safe vehicle operation.
    3. Ensure the heater and defroster are operating properly.
    4. Check the operation of all interior lights.
      1. Turn on the headlamps and leave them on. If equipped, ensure all gauge bulbs illuminate. If equipped, ensure ICU screens illuminate.
      2. Ensure all equipped driver control switches illuminate and verify the interior cab lights controlled by these switches illuminate.
      3. Ensure both turn signal indicators illuminate when the turn signal switch is activated.
    5. Check the operation of all exterior lamps manually or, if equipped, by using either the LIGHT TEST switch on the dash or the Lamp Check button on the key fob.

      1. Auxiliary Turn Signal Lamp

      2. Clearance Lamps

      3. Identification Lamps

      4. Side Marker Lamps (driver side shown)

      5. Side Marker Lamps

      6. DRL/Accent Lamp/Turn Signal

      7. Headlamp, Low Beam

      8. Headlamp, High Beam

      9. Stop Lamps, Tail Lamps, Turn Signals, and Back-Up Lamp

      Fig. 1, Exterior Lights

    6. To check exterior lamps manually:
      1. Turn the ignition switch to the ACC or ON position.
      2. Make certain the parking brake is set.
      3. Activate the high-beam headlamps and hazard warning lamps.
      4. Exit the cab and check that all exterior lamps and reflectors are clean and intact.
      5. Check that the brake lamps, tail lamps, headlamps, turn signals, marker lamps, identification lamps, and clearance lamps are working properly.
    7. To check the exterior lamps using the dash LIGHT TEST switch, see Fig. , or key fob Lamp Check button, see Fig. :

      Fig. 2, Pretrip Light Test Switch

      1. Door Lock

      2. Door Unlock

      3. Lamp Check

      Fig. 3, Key Fob

        Note: Factory settings have groups of lamps activate sequentially up to 100 times or until manually stopped.

      1. Make sure the parking brake is set.

        2. Note: LED accent lighting turns off when the high beam headlamps turn on.

      2. Press either the LIGHT TEST switch or Lamp Check button to begin the pretrip light inspection. If equipped, groups of lamps cycle on and off in the following sequence:

        • Group 1: Always ON: marker lamps, clearance lamps, tail lamps, licence plate lamp

        • Group 2: Low beam headlamps

        • Group 3: High beam headlamps and stop lamps

        • Group 4: Backup lamps and daytime running lamps

        • Group 5: Front and rear fog lamps

        • Group 6: Turn signals and utility lamps

      3. Walk around the truck and check that the lamps are working properly.
      4. Verify that all exterior lights and reflectors are clean and intact.
      5. The pretrip light inspection can be stopped by:

        • releasing the parking brake;

        • Pressing either the LIGHT TEST switch on the dash or the Lamp Check button on the key fob.

      8. Warning: Inspect and maintain seat belts. When any part of a seat belt system needs replacement, the entire seat belt must be replaced, both retractor and buckle side. Any time a vehicle is involved in an accident, and the seat belt system was in use, the entire vehicle seat belt system must be replaced before operating the vehicle. Do not attempt to modify the seat belt system; doing so could change the effectiveness of the system. Failure to replace worn or damaged seat belts, or making any modifications to the system, may result in personal injury or death.

    8. Inspect the seat belts and tether belts.
      1. Check the web for fraying, cuts, extreme dirt and dust, or for severe fading from exposure to sunlight, especially near the buckle latch plate and in the D-loop guide area.
      2. Check operation of the buckle, latch, Komfort Latch or Sliding Komfort Latch (if equipped), web retractor, and upper seat belt mount on the door pillar. Check all visible components for wear or damage.
      3. Check the seat belt and tether belt connection points and tighten any that are loose.

      9. Warning: Never fill fuel tanks to more than 95 percent of their liquid capacity. This could make them more likely to rupture from impact, possibly causing fire and resulting in serious personal injury or death by burning.

      Do not mix gasoline or alcohol with diesel fuel. This mixture could cause an explosion, possibly resulting in serious personal injury or death. Do not fill the fuel tanks in the presence of sparks, open flames, or intense heat. These could ignite the fuel, possibly causing severe burns.

      Important: Use ultralow-sulfur diesel (ULSD) with 15 ppm sulfur content or less. Failure to use ULSD fuel may void the warranty on emission components.

    9. Check the fuel level in the fuel tank(s). To keep condensation to a minimum, fuel tanks should be filled at the end of each day.
    10. Adjust the rearview and down view mirrors as necessary.
    11. Test the park brakes.
      1. With the engine running and air system fully charged, set the parking brake.
      2. Put the vehicle in the lowest gear and gently attempt to move it forward. The vehicle should not move.

        If the vehicle moves, the parking brakes are not operating correctly and must be repaired before the vehicle is operated.

    12. Test the backup alarm.
      1. Release the parking brake and put the transmission in reverse.
      2. Move the vehicle slightly backward to ensure that the backup alarm is operating correctly.
    Note:
    Parent topic: Daily Pretrip Inspections and Maintenance
    Document Number: 0000157225
    Manual Publication Date: 2025-03-10
    Topic Publication Date: 2025-06-02