Seat Electrical 101

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Memory Seats Description and Operation: 2002 Chevy and GMC

Memory Seat System Components

The memory seat system consists of the following components:

* Power seat switch assembly
* Memory recall switch assembly
* Horizontal adjuster motor
* Front vertical adjuster motor
* Rear vertical adjuster motor
* Recline adjuster motor
* Memory seat module
* SEAT 25A circuit breaker
* MIR/LOCK 3A fuse
* IGN3 10A fuse

Memory Seat System Description

Battery voltage is supplied to the memory seat module from the SEAT 25A circuit breaker. The memory seat module supplies the seat adjuster switch assembly with a battery positive reference voltage. While the seat adjuster switches are in an inactive state the switch contacts are closed to the adjuster switch ground circuit. When a seat adjuster switch is pressed to an active state the switch contact is closed to the reference voltage circuit. Battery voltage on a switch signal circuit indicates to the memory seat module the switch status is active. Each seat adjuster motor is controlled by the memory seat module through 2 motor control circuits. While the seat adjuster motors are in an inactive state the motor control circuits are closed to ground circuit contacts within the memory seat module. The memory seat module operates the seat adjuster motors by switching one of a motor's control circuits to battery voltage. The seat adjuster motors are bidirectional and the direction of adjuster motor rotation is determined by which of the adjuster motor control circuits is switched to battery voltage while the other remains grounded.

Memory Set/Recall Operation

The seat adjuster motors are equipped with internal position sensors. The adjuster motor position sensors are monitored by the memory seat module and are used to determine the seat position when storing or recalling memory settings. The horizontal, front vertical, and rear vertical adjuster motors use hall effect type position sensors. The hall effect position sensors are supplied with 5-volt reference and ground circuits from the memory seat module. The position sensor signal circuits are supplied 5 volts through a resistor them monitored within the memory seat module. During adjuster motor operation the hall effect position sensor provides a single pulse for every revolution of the adjuster motor shaft. The memory seat module counts the pulses from the position sensor signal circuits to determine the adjuster motor positions when storing or recalling memory seat position settings. The recline adjuster motor is equipped with a potentiometer type position sensor. The recline motor position sensor is supplied with it's own 5-volt reference and ground circuits from the memory seat module. The recline position sensor signal circuit is supplied 5 volts through a resistor then monitored within the memory seat module. The signal voltage monitored by the memory seat module ranges from 0.39 - 4.58 volts and is determined by the wiper location on the resistor within the recline motor position sensor. The recline motor position sensor signal circuit voltage level is used by the memory seat module to determine the seat recline position when storing or recalling memory seat position settings.

The memory recall switch assembly on the driver's door provides inputs to the memory seat module. Battery voltage is supplied to the memory recall switch assembly from the MIR/LOCK 3A fuse. When a SET, RCL 1, or RCL 2 switch is pressed, the switch contacts close the appropriate switch signal circuit to the battery voltage supply circuit within the memory recall switch assembly. Battery voltage on a switch signal indicates to the memory seat module the switch status is active.

Memory seat recall operation is allowed only with the transmission selector lever in the PARK position while the ignition is on. The memory seat module determines the ignition is on using the ignition voltage supply circuit from the IGN3 10A fuse. The memory seat module relies on in input from the shift lock control switch supply circuit in order to determine transmission selector lever is in the PARK position.

Heated Seats Description and Operation

Heated Seats System Components

The heated seats system for the driver and passenger seat consists of the following components:

* Heated seat switch
* Seat cushion heater element
* Seat back heater element
* Heated seat module
* Heated seat cushion thermistor
* PTC device
* SEO2 30A fuse
* IGN3 10A fuse

Heated Seats System Operation

Both the driver and passenger seats have 2 heating elements. One is in the seat cushion and the other is in the seat back. The heated seats are capable of obtaining temperatures of 98?F in LOW mode and 107?F in HIGH mode. Battery voltage is supplied to the heated seat module from the SEO2 30A fuse and through a PTC device. The PTC is hardwired in the battery voltage supply circuit in the seat harness assembly and provides extra circuit protection. Ignition voltage is supplied to the heated seat switch from the IGN3 10A fuse. When the heated seat switch is pressed ignition voltage is supplied to the solid state switching device within the heated seat switch assembly. The first time the heated seat switch is activated the solid state switching device supplies voltage to illuminate the high LED indicator and a signal voltage to the heated seat module indicating the high mode is active. The second time the heated seat switch is activated the solid state switching device supplies voltage to illuminate the low LED indicator and a voltage signal to the heated seat module indicating the low mode is active. When the heated seat module receives a high or low mode active signal from the heated seat switch signal circuit, battery voltage is supplied to the seat cushion and back heater elements. The heated seat cushion thermistor provides a signal to the heated seat module used to determine the seat cushion temperature. The heated seat module regulates the supply voltage to the heater elements according to the inputs from the heated seat switch and the seat cushion thermistor.

Power Seats System Description and Operation

Power Seat System Components

The power seat system for the driver and passenger consists of the following components:

* Power seat switch assembly
* Horizontal adjuster motor
* Front vertical adjuster motor
* Rear vertical adjuster motor
* Recline adjuster motor
* SEAT 25A circuit breaker

Power Seat System Operation

There are 2 options of power seats available with this system. One option is the base power seat and it is limited to positioning the seat vertically and horizontal only. The other option is a full feature seat that can position the seat vertically, horizontally and reclining the back cushion. Battery voltage is supplied to the power seat switch from the SEAT 25A circuit breaker. While the seat adjuster switches are in an inactive state the switch contacts are closed to the adjuster switch ground circuit. When a seat adjuster switch is pressed to an active state the switch contact is closed to the battery voltage supply circuit. Each seat adjuster motor is controlled by the seat adjuster switch through 2 motor control circuits. The seat adjuster motors are bidirectional and the direction of adjuster motor rotation is determined by which of the adjuster motor control circuits is switched to battery voltage while the other remains grounded.

Lumbar Support Description and Operation

Lumbar Support System Components

The lumbar support system for the driver and passenger seat consists of the following components:

* Lumbar/bolster switch
* Seat lumbar motor
* Seat bolster motor
* SEAT 25A circuit breaker

Lumbar Support System Operation

The lumbar support and bolster motors are operated by a four position switch in each seat. Battery voltage is supplied to the lumbar/bolster switch from the SEAT 25A circuit breaker. While the lumbar/bolster switches are in an inactive state the switch contacts are closed to the lumbar/bolster switch ground circuit. When a lumbar/bolster switch is pressed to an active state the switch contact is closed to the battery voltage supply circuit. Each lumbar/bolster motor is controlled by the lumbar/bolster switch through 2 motor control circuits. The lumbar/bolster motors are bidirectional and the direction of motor rotation is determined by which of the motor control circuits is switched to battery voltage while the other remains grounded.

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2003 &> (based on 03):

(To date)

Power Seats System Description and Operation

Power Seat System Operation

There are 2 options of power seat systems available in full size trucks. The 6 way driver and passenger power seats, and 8 way driver and passenger power seats with driver memory. For the driver memory seat operation refer to Memory Seats Description and Operation . Power seats without memory are completely controlled through the power seat switch. Battery voltage is supplied to the power seat switch through the power seat circuit breaker. While the seat adjuster switches are in an inactive state the switch contacts are closed to the power seat switch ground circuit. When a power seat switch is pressed to an active state the switch contact is closed to the battery voltage supply circuit. Each seat adjuster motor is controlled by the power seat switch through 2 motor control circuits. The seat adjuster motors are bidirectional and the direction of adjuster motor rotation is determined by which of the adjuster motor control circuits is switched to battery voltage while the other remains grounded.


Memory Seats Description and Operation

Memory Seat System Components

The memory seat system consists of the following components:

* Power seat switch assembly
* Memory recall switch assembly
* Horizontal adjuster motor
* Front vertical adjuster motor
* Rear vertical adjuster motor
* Recline adjuster motor
* Driver seat module
* Driver door module
* SEAT 30A circuit breaker

Memory Seat System Description

Battery voltage is supplied to the driver seat module through the power seat circuit breaker. The driver seat module supplies the seat adjuster switch assembly with a battery positive reference voltage. While the seat adjuster switches are in an inactive state the switch contacts are closed to the adjuster switch ground circuit. When a seat adjuster switch is pressed to an active state the switch contact is closed to the reference voltage circuit. Battery voltage on a switch signal circuit indicates to the driver seat module the switch status is active. Each seat adjuster motor is controlled by the driver seat module through 2 motor control circuits. While the seat adjuster motors are in an inactive state the motor control circuits are closed to ground circuit contacts within the driver seat module. The driver seat module operates the seat adjuster motors by switching one of a motor's control circuits to battery voltage. The seat adjuster motors are bidirectional and the direction of adjuster motor rotation is determined by which of the adjuster motor control circuits is switched to battery voltage while the other remains grounded.

Memory Set/Recall Operation

The seat adjuster motors are equipped with internal position sensors. The adjuster motor position sensors are monitored by the driver seat module and are used to determine the seat position when storing or recalling memory settings. The horizontal, front vertical, and rear vertical adjuster motors use hall effect type position sensors. The hall effect position sensors are supplied with battery positive reference and ground circuits from the driver seat module. The position sensor signal circuits are supplied battery positive voltage through a resistor them monitored within the driver seat module. During adjuster motor operation the hall effect position sensor provides a single pulse for every revolution of the adjuster motor shaft. The driver seat module counts the pulses from the position sensor signal circuits to determine the adjuster motor positions when storing or recalling memory seat position settings. The recline adjuster motor is equipped with a potentiometer type position sensor. The recline motor position sensor is supplied with it's own 5-volt reference and ground circuits from the driver seat module. The recline position sensor signal circuit is referenced from ground within the driver seat module. The signal voltage monitored by the driver seat module ranges from 0.39 - 4.58 volts and is determined by the wiper location on the resistor within the recline motor position sensor. The recline motor position sensor signal circuit voltage level is used by the driver seat module to determine the seat recline position when storing or recalling memory seat position settings.

The memory recall switch assembly on the driver's door provides inputs to the driver door module. Battery voltage is supplied to the memory recall switch assembly from the driver door module. When a RCL 1, RCL 2, or EXIT switch is pressed, the switch contacts close the appropriate switch signal circuit to the battery voltage supply circuit within the memory recall switch assembly. When the driver door module receives active switch signals from the memory recall switch assembly, the appropriate commands are sent to the driver seat module using the Class 2 Serial Data circuit.

Memory seat recall operation is allowed only with the transmission selector lever in the PARK position while the ignition is on. The transmission selector lever position data is provided to the driver seat module by a message through the Class 2 Serial Data circuit.

Lumbar Support Description and Operation

Lumbar Support/Torso Bolster System Components

The lumbar support/torso bolster system for the driver and passenger consists of the following components:

* Driver and passenger lumbar support/torso bolster switches
* Driver and passenger lumbar support/torso bolster motor assemblies
* Driver seat module
* Memory select switch
* Driver door module
* SEAT 30A circuit breaker

Lumbar Support/Torso Bolster System Operation

The power lumbar support/torso bolster system is only available with the driver memory, 8 way power seats option. The driver seat lumbar and torso adjuster motors are controlled through the driver seat module, while the passenger seat lumbar and torso adjuster motors are controlled directly through the lumbar support/torso bolster adjuster switch.

The driver seat module supplies the driver seat lumbar support/torso bolster adjuster switch assembly with a battery positive reference voltage. While the switches are in an inactive state the switch contacts are closed to the switch ground circuit. When a switch is pressed to an active state the switch contact is closed to the reference voltage circuit. Battery voltage on a switch signal circuit indicates to the driver seat module the switch status is active. Each seat adjuster motor is controlled by the driver seat module through 2 motor control circuits. While the seat adjuster motors are in an inactive state the motor control circuits are closed to ground circuit contacts within the driver seat module. The driver seat module operates the seat adjuster motors by switching one of a motor's control circuits to battery voltage. The seat adjuster motors are bidirectional and the direction of adjuster motor rotation is determined by which of the adjuster motor control circuits is switched to battery voltage while the other remains grounded.

The seat adjuster motors are equipped with internal position sensors. The adjuster motor position sensors are monitored by the driver seat module and are used to determine the seat position when storing or recalling memory settings. The lumbar and torso adjuster motors use hall effect type position sensors. The hall effect position sensors are supplied with battery positive reference and ground circuits from the driver seat module. The position sensor signal circuits are supplied battery positive voltage through a resistor them monitored within the driver seat module. During adjuster motor operation the hall effect position sensor provides a single pulse for every revolution of the adjuster motor shaft. The driver seat module counts the pulses from the position sensor signal circuits to determine the adjuster motor positions when storing or recalling memory seat position settings.

Battery voltage is supplied to the passenger seat lumbar support/torso bolster switch through the SEAT 30A circuit breaker. While the switches are in an inactive state the switch contacts are closed to the switch ground circuit. When a switch is pressed to an active state the switch contact is closed to the battery voltage supply circuit. Each motor is controlled by the power seat switch through 2 motor control circuits. The motors are bidirectional and the direction of motor rotation is determined by which of the motor control circuits is switched to battery voltage while the other remains grounded.

Heated Seats Description and Operation Front

Heated Seat Components

The heated seat system consists of the following components:

* Driver and passenger heated seat switches
* Driver and passenger seat back heater elements
* Driver and passenger seat cushion heater elements
* Driver and passenger seat back temperature sensors
* Driver seat module
* Driver door module
* Passenger door module

Heated Seat System Operation

The driver and passenger heated seats have 2 heat zone operating modes with 3 heat level modes and will operate only while the engine is running. The heat zones are determined by which of the 2 heated seat buttons are pressed, while the heat level is determined by the number of times they are pressed. Pressing the seat cushion button 1 time will activate the seat back and cushion heater elements in the high mode. Each time the seat cushion button is pressed the seat back and cushion heat level is reduced from high to medium, low, and off. Pressing the heated seat back button 1 time will activate only the seat back heater element in the high mode. Each time the seat back button is pressed the seat back heat level is reduced from high to medium, low, and off. During heated seat operation the heat zone operating mode may be changed without affecting the current heat level mode.

The heated seat switches are momentary contact switches and are inputs to the driver and passenger door modules. Battery voltage is supplied to the switch assembly from the door module, and when a heated seat switch is pressed and released a brief switch signal voltage is supplied to the door module. Whenever the door module receives an active heated seat switch input, the next heated seat operating mode is determined by whatever the current mode may be. The seat heater elements are controlled by the driver seat module using inputs from the door modules through Class 2 serial data circuit messages. The driver seat module controls the voltage supply and the ground circuits to the seat heater elements. When a heated seat function is commanded active, the seat module will switch battery voltage to the heater element supply circuits, and ground is provided through low side drive control circuits. During heated seat operation both the seat back and cushion heater elements are supplied battery voltage. The seat module grounds the appropriate control circuits for back only or back and cushion heating modes, and opens or closes the active control circuits as necessary in order to maintain the desired seat temperature. The seat module relies on inputs from thermistors located in the driver and passenger seat backs to control heated seat temperatures. The thermistors are 2 wire sensors supplied with a 5-volt referenced signal circuit and a low reference circuit from the seat module. Resistance through the thermistors varies with temperature causing the heated seat sensor signal circuit voltage levels to decrease as the seat back temperatures rise. The seat modules allow heated seat operation only while the engine is running which is determined by a Class 2 serial data circuit message from the powertrain control module.

And for the Cadillac owners...

Heated Seats Description and Operation Rear

Rear Heated Seat Components

The rear heated seat system consists of the following components:

* Left and right seat cushion heater elements
* Left and right heated seat control modules
* Left and right heated seat switches
* IGN 3 10A fuse
* SEO B1 15A fuse

Rear Heated Seat Operation

The rear heated seat system will heat the rear seat cushions in high or low heat modes. Battery voltage to the seat cushion heater elements is controlled by the heated seat control modules using inputs from the heated seat switches and the seat cushion temperature sensors. The heated seat switch signal circuit is supplied with a reference voltage through a resistor and monitored within the control module. The heated seat switch is a momentary contact type and when activated the signal circuit is briefly closed to ground. Whenever the control module receives an active switch input, the heated seat operating mode is determined by whatever the current mode may be, from off to high then low. The control module monitors the seat cushion temperature by sending a signal voltage through a thermistor located in the heater element pad. The control module cycles the battery voltage circuit to the heater element as necessary in order to maintain the desired seat cushion temperature.