Lumbar Supports

The Lumbar Seat incorporates a power inflate/power deflate pneumatic system which controls the 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 Assembly, the 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 LEFT or RIGHT position. This action provides battery voltage to each of the four comfort feature switches and prepares a ground path (from terminal A, connector C2, on the Console Seat Switch) for either LH or RH Seat Solenoid Valve Assemblies.

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 is energized. 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 G304.

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 LEFT position and the Console Switch is held in the INFLATE position, the Inflate Relay will be energized through the WHT (766) wire and the Lumbar Solenoid in the LH Seat Solenoid/Valve Assembly will be energized through the BRN (763) wire. Battery voltage will also be applied to the right Lumbar Solenoid, but the solenoid will not be energized because there will not be a path to ground. The ground path for the LH Seat Solenoid is through the TAN/BLK (797) wire to terminal B on connector C2 on the Console Seat Switch, through the normally closed contacts of the Pressure Cut-Out Relay and to ground G304 through the BLK (150) wire at terminal B of the Seat Control Module.

The purpose of the Deflate and Inflate Relay is to apply voltage of the proper polarity to the Seat Air Pump Assembly. When the Inflate Relay is energized, battery voltage at terminal F of the Seat Control Module is applied through the closed contacts of the Inflate Relay to terminal A of the Seat Air Pump Assembly 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 (150) 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 Assembly 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.