SFN-20240102E Reconfigure low air pressure buzzer

  • 3 minute(s) read
Prev Next

TICO Document #: SFN-20240102E (formerly TES 196)

Description of Procedure: n.a

Units Affected: N/A

Parts Required: N/A

Planned Labor: N/A

Instructions:

  1. Park the vehicle on a flat surface, and apply the parking brake and chock wheels. If your company utilizes a “Lock Out, Tag Out” policy, you should employ it during this procedure.

  2. Remove the battery box cover and disconnect the battery cables. Remove batteries or insulate terminal ends with a non-conductive wrap to prevent inadvertent contact between battery terminals and cables.

  3. Release/vent all air in the system. This can be done by manually releasing valves at the bottom of the air tank.

  1. Inside the cab, remove the gauge panel by removing #10 socket head screws with 1/8” hex key wrench. The panel is located at the top of the dash cover.  There are 7 screws for this panel.

  1. Gently tilt the gauge panel away from dash cover.  This will expose the back of the panel and the wires attached to the gauges.

  1. On the top right hand side of gauge panel, remove the connector for flood lights/work lights switch.

  1. Remove air line(s) for air pressure gauge. Continue lifting the gauge panel away from the dash cover assembly so that relay power block is exposed.

  1. Continue lifting gauge panel away from dash cover assembly.  Locate the connector between the dash gauge harness and cab PDC harness, shown above. 

  1. Unscrew connectors and securement hardware using 5/16 bit driver.

  1. Remove leads to the hour meter, shown on left.

    Note: red wire on terminal 1, white wire on terminal 2, and brown wire on terminal 3.

  2. Remove dash gauge panel with attached harness from dash cover and bucket assembly, set this aside for now.

  1. Splice a white jumper wire to the jumper harness 91273 with a #10 ring terminal on the end.

    12A The spliced jumper wire should be approximately 2 ft. long.

  1. Connect jumper harness to low air buzzer 91271. 

    13A Observe polarity on buzzer.  Yellow wire must be connected to positive terminal and white wire must be connected to negative terminal.

  1. Prepare the low air pressure switch, 91272, by attaching it and two ¼” tube x ¼” NPT straight adapters, 40883, to a ¼” NPT pipe tee, 42295, as shown above.

Note: the terminals on this pressure switch do not have any polarity designation.

  1. Connect the ring terminal from the jumper harness, 91273, to the pressure switch.

  2. Install a 2 ft. long jumper wire onto the opposite terminal of the pressure switch using a #10 ring terminal. The free end of the jumper wire should have a 5/16” ring terminal.

  1. Locate the relay power block shown above.

  1. Remove the existing low air pressure buzzer, 90873, from relay power block.  

  1. Connect the yellow wire of the jumper harness, 91273, into cavity 86 of the relay module, where low air pressure buzzer was removed.  Connect the white wire of the jumper harness to cavity 87.

  2. Connect the 5/16” ring terminal on the pressure switch to the relay block ground stud.

  3. Tie strap jumper harness to wire bundle of cab PDC, ensure there is no chaffing of wires.

  1. Connect the existing air pressure gauge supply line to one of the straight adapters on the low air pressure switch. 

  2. Connect a 2 ft. piece of ¼” yellow tubing to the other straight adapter on the pressure switch.

  3. Place the pressure switch at the bottom of the bucket to the right of the power relay block.

  4. Position the pressure switch such that the dust cap is at the top.

  1. Disconnect and tie back the two wires from the existing low air pressure switch, 40776, located on top of the right air tank.  

  2. Remove the existing low air pressure switch and replace it with a brass plug, 40824.

  1. Reconnect the gauge panel in reverse order.

  2. Reconnect battery cables to appropriate battery terminals.

  1. Turn the ignition switch to the on position. The buzzer should be engaged, emitting sound.  If not, check wiring and fuse F15 at the fuse panel on the left-hand side of the dash, then repeat the process.

  2. Start and idle the engine until the air pressure gauge shows 80 psi. The buzzer should be silent at this time.  Operate treadle, brake, and valve several times until air pressure falls below 70 psi.  Buzzer should reengage.  If not, check the wiring and fuse F15.

  3. Secure gauge panel in place with #10 machine screws previously removed.

  1. Remove “Lock Out, Tag Out” plaque.

  1. Return vehicle to service.