Air Suspension System

Many thanks to Len Mortimer for the cover art work & all those GMC Pacific Cruisers that reviewed this document prior to publication.

The contents of this document are based upon personal experience gained by "Hands-On" vehicle maintenance over many years. They are "One Man's" viewpoint & do not represent authorized data pertaining to the GMC Motorhome. It is the reader's responsibility to establish his/her position associated with each subject matterbefore vehicle repair and/or modifications are accomplished.

AIR SUSPENSION SYSTEM
CONFIGURATIONS
________________________________

POWER-LEVEL (73-75 COACHES

-ROTARY VALVE CONTROLS

-SINGLE AIR COMPRESSOR (DANA)

ELECTRO-LEVEL I (75-78 COACHES)

-SWITCH TYPE CONTROL PANEL

-SINGLE AIR COMPRESSOR (DANA)

ELECTRO-LEVEL II (78 COACHES)

-SWITCH TYPE CONTROL PANEL

-DUAL AIR COMPRESSORS (GM)

POWER-LEVEL AIR SYSTEM
SCHEMATIC (73-75 MODELS)

AC=Air Compressor, HS=Height Sensor, PS=Pressure Switch

ELECTRO-LEVEL I AIR SYSTEM
SCHEMATIC (75-78 MODELS)

AC=AIR COMPRESSOR, HS=HEIGHT SENSOR, PS=PRESSURE SWITCH

ELECTRO-LEVEL I CONTROL PANEL
SCHEMATIC

ELECTRO-LEVEL II AIR SYSTEM
SCHEMATIC (78 MODELS)

ELECTRO-LEVEL II CONTROL PANEL
SCHEMATIC

HEIGHT CONTROL SENSOR OPERATION
ELECTRO-LEVEL II

AIR SUSPENSION SYSTEM
IMPROVEMENT CONSIDERATIONS

ALL SYSTEMS

Install Upgrade Kit (Cinnabar 1-800-720-CBAR)

5 Micron Filter, Stainless Steel Check Valve, Pressure Relief Valve, Air Pressure Gauge (P-Level & E-Level I)

Convert Low Air Sensor Wiring to AC "ON" Indicator

Remove Sensor, Plug Hole, and Route through Pressure Switch, (2nd Pole)

Clean and Lubricate Electrical Connections including Ground

Revise AC +12V Power Wiring for "Stiff" Power Source

Change at Relay for E-Level I & II (30 AMP CB)

Add Power Relay for P-Level (30 AMP CB)

POWER-LEVEL SYSTEM ('73 / '74 Coaches)

Relocate Air Tank to Driver's Side (Away from Battery)

Hang Vertically Near AC

Relocate Air Pressure Switch to Sense Air Tank Pressure

ELECTRO-LEVEL I SYSTEM ('75 / '78 Coaches)

Replace Plastic Air Hose Fittings with Brass Fittings

ELECTRO-LEVEL II ('78 Coaches)

Modify Control Logic to Activate "HOLD SOLENOID" Only When Raising or Lowering Coach (Auto & Manual Modes)

ALL SYSTEMS....ADJUST RIDE HEIGHT AS NECESSARY

AIR SUSPENSION SYSTEM
TROUBLE SHOOTING CONSIDERATIONS

Soap & Water to Detect Leak Source

Interchange Componenets & Observe Results to Isolate Leak

-Temporarily Cross Air Batg Hoses to Isolate Leak Between Air Bag & Air Distribution Section (EL I & EL II)

-Swap Rotary Valves to Isolate to Rotarty Valve (P-Level)

Remove Selective Components & Plug Air Source to Isolate

If Height Steady in Hold Mode...Suspect Air Distribution Section

Worn Rotary Valve Knob Detent Tab Causes Erratic Operation

-Replace or Shim Knob

AC Rebuilt Kits Available for "Tired" Compressors

-See John Clement (951)737-0969

Rotate "Hot Dog" Bags 180 Degrees BEFORE they Collapse

KEEP SYSTEM TIGHT & Avoid Overloading Tires with Unlevel Coach

POWER IMPROVEMENT CONSIDERATIONS
POWER LEVEL

POWER IMPROVEMENT CONSIDERATIONS
ELECTRO-LEVEL I

POWER IMPROVEMENT CONSIDERATIONS
ELECTRO-LEVEL II