Diagnostic Information for Inoperative Air Seats, Air Horn and/or Exhaust Brake and Release of New Auxiliary Air Compressor Relay and Pressure Switch on RPO K16 Vehicles

This bulletin is being revised to add models and warranty information. Please discard Corporate Bulletin Number 05-08-133-001 (Section 08 -- Body & Accessories).

The following diagnosis may be helpful if any of the above vehicles exhibit an inoperative air seat, air horn and/or exhaust brake.

During diagnosis of the above conditions, the technician may find an inoperative auxiliary air compressor. Technicians should inspect the auxiliary air compressor relay (1) for pin non-contact or possibly burnt pins. The air compressor reservoir air pressure switch has been found to be the cause of the affected relay. The switch may be cycling the relay on and off too rapidly and causing the air compressor to become inoperative.

If normal diagnostics lead to either of these components being the cause of the inoperative air compressor, the only repair is to replace the reservoir air pressure switch and the air compressor relay.

A new air compressor pressure switch and relay is available should these components need replacement. See the Parts Information below.

Refer to the Air Compressor - Auxiliary sub-section in SI for diagnostic and repair information.