Lumbar Supports

CIRCUIT OPERATION
The Lumbar Seat System is an Electro/Pneumatic system which controls the comfort features of the seat by inflating or deflating air bladders within the seat. The major components of the system consist of the Console Seat Switch, the Seat Air Pump Assembly, the Seat Control Module and the Seat Solenoid Valve Assemblies (also pneumatic lines and air bladders).

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 applies battery voltage to each of the comfort feature switches and allows a ground path (from terminal "A" connector C2, on the Console Seat Switch) for either LH or RH Seat Solenoid Valve Assemblies. The "ground path" originates at the Seat Control Module and is interrupted by the Pump Cut-off Relay in an over-pressure/vacuum situation (i.e. when the air bladder in the seat becomes "full" or "empty.")

All of the comfort feature switches operate in a similar manner. When one is moved to the "INFLATE" position, battery voltage is applied to the coil of the Inflate Relay (in the Seat Control Module), which is energized. Ground for the Inflate Relay (and Deflate Relay) is provided at terminal "B" of the Seat Control Module. "DEFLATE" mode operates in a similar manner.

When the Inflate Relay is energized, battery voltage at terminal "F" of the Seat Control Module is applied to the Seat Air Pump Assembly (CKT 768 terminal "A"). The Seat Air Pump Assembly is grounded (CKT 767 terminal "B") through the normally closed contacts of the Pump Cut-off Relay, the normally closed contacts of the Deflate Relay and CKT 150 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. 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.

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

At the same time, battery voltage is applied to the associated coil in the Solenoid Valve Assemblies from the feature switch. When 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 CKT 766 and the Lumbar Solenoid in the LH Seat Solenoid/Valve Assembly will be energized through CKT 763.

When an "Inflate" (or "Deflate") button is pressed, battery voltage is applied to one side of the appropriate solenoid valve coil located in the LH and RH Seat Solenoid Valve Assembly. Ground is routed to the LH or RH Seat Solenoid Valve Assembly corresponding to the position of the Seat Select Switch ("L" or "R").

Ground for the seat solenoid valves originates at the Seat Control Module terminal "E" (CKT 150) and is interrupted by the Pump Cut-off Relay when the air bladder becomes "Full" or "Empty."