Except STE

The Lumbar Seat has a power inflate/power deflate pneumatic system used for controlling comfort features of the seat by inflating or deflating air cells within the seat. The major components of the pneumatic system consist of the Console Seat Switch, the Seat Air Pump Motor, the Pneumatic Seat Control Module and the Seat Solenoid Valve Assemblies.

Power is applied at all times to terminal A of connector C1 on the Console Seat Switch. Whenever an adjustment is to be made, the Seat Select Switch must be set to the DRIVER or PASSENGER position. This action provides battery voltage to each of the seven comfort feature switches and prepares a ground path (from terminal A, connector C2, on the Console Seat Switch) for either the Driver or Passenger Seat Solenoid Valve Assembly.

All of the comfort feature switches operate in a similar manner. If any one of them is moved to the INFLATE position, for example, battery voltage is applied through the WHT (766) wire to the Inflate Relay, which then energizes. When any one of the switches is moved to the DEFLATE position, battery voltage is applied through the GRY (764) wire to energize the Deflate Relay. The Inflate and Deflate Relays are grounded through the BLK (150) wire at ground G306.

At the same time, battery voltage is also applied to the associated solenoid coil in the Solenoid Valve Assemblies from the other half of the feature switch. If, for example, the Seat Select Switch is moved to the DRIVER position and the Middle Lumbar Switch is held in the INFLATE position, the Inflate Relay will be energized through the WHT (766) wire and the Middle Lumbar Switch is held in the INFLATE position, the Inflate Relay will be energized through the WHT (766) wire and the Middle Lumbar Solenoid in the Driver's Seat Solenoid/Valve Assembly will be energized through the BRN (763) wire.

Battery voltage will also be applied to the Passenger's Middle Lumbar Solenoid, but the Solenoid will not be energized because there will not be a path to ground. The ground path for the Driver's Seat Solenoid is through the normally closed contacts of the Pressure Cut-Out Relay and to ground G306 through the BLK (150) wire at terminal B of the Pneumatic Seat Control Module.

The purpose of the Deflate and Inflate Relay is to apply voltage of the proper polarity to the Seat Air Pump Motor. When the Inflate Relay is energized, battery voltage at terminal F of the Pneumatic Seat Control Module is applied through the closed contacts of the Inflate Relay to terminal A of the Seat Air Pump Motor through the PNK (768) wire. Terminal B of the Seat Air Pump Assembly is grounded through the normally closed contacts of the Pressure Cut-Out Relay, the normally closed contacts of the Deflate Relay and the BLK (250) wire at terminal E of the Seat Control Module.

When the Deflate Relay is energized, battery voltage is applied to terminal B of the Seat Air Pump Motor through the normally closed contacts of the Pressure Cut-Out Relay. Terminal A is grounded through the normally closed contacts of the Inflate Relay.

In this way, the air pump will run in either direction to inflate or deflate the bladders in the seat as required.

Should any of the bladders become fully inflated or deflated, the increased pressure or vacuum will operate the Pressure Cut-Out Switch. This will allow the Pressure Cut-Out Relay to be energized whenever the Air Pump is operated. When the Pressure Cut-Out Relay is energized, the Air Pump Motor Circuit and Solenoid Valve Circuit are interrupted.