Automotive Electrical and Electronic Systems Classroom Manual Fifth Edition Update by John F. Kershaw

Body Accessory Systems Operation 333
command. In response to this signal, the heated
seat module applies battery positive voltage to
the seat cushion/back heating elements, setting
the temperature level to high heat. When the
heated seat switch is pressed a second time, the
heated seat high/low signal circuit of the heated
seat module is again momentarily grounded
through the HI/LO switch contacts, indicating a
low heat command. In response to this second
signal, the heated seat module then sets the temperature
level to low heat. When the heated seat
switch is pressed a third time, the heated seat
high/low signal circuit of the heated seat module
is again momentarily grounded through the
HI/LO switch contacts, indicating a heat off command.
In response to this signal, the heated seat
module removes battery voltage from the seat
heating elements.
Front Heated Seat Switch
Indicators
When the heated seat is off and the front heated
seat switch is pressed once, the heated seat temperature
is set to high heat. The heated seat module
applies 5 volts through the heated seat high
temperature indicator control circuit to the heated
seat switch, illuminating the high temperature
indicator. When the switch is pressed a second
time the heated seat temperature is set to low heat.
The heated seat module applies 5 volts through
the heated seat low temperature indicator control
circuit to the heated seat switch, illuminating the
low temperature indicator. After the switch is
pressed a third time, the heated seat is turned off,
and the front heated seat module removes the
voltage from the low temperature indicator.
Rear Heated Seat Operation
When the heated seat switch is first pressed,
the heated seat switch signal circuit of the rear
door module is momentarily grounded through
the switch contacts, indicating a high heat command.
The rear door module then sends a simple
buss interface (SBI) message to the driver’s
door module (DDM), indicating the high heat
command. The DDM then sends out a Class 2
message to the rear integration module (RIM),
indicating the high heat command. The RIM
momentarily sends a 35-millisecond one-shot
pulse signal that is pulled low through the heated
seat switch signal circuit of the rear heated seat
module, indicating the high heat command.
In response to this signal, the heated seat module
will then apply battery positive voltage to the seat
cushion/back heating elements, setting the temperature
level to high heat.
When the switch is pressed a second time, the
heated seat switch signal circuit of the rear door
module is again momentarily grounded, indicating
a low heat command. The rear door module
then sends out a SBI message to the DDM,
indicating the low heat command. The DDM then
sends out a Class 2 message to the RIM, indicating
the low heat command. The RIM again
momentarily sends a 35-millisecond one-shot
pulse signal that is pulled low through the heated
seat switch signal circuit of the heated seat module,
indicating the low heat command. In
response to this signal, the heated seat module
then sets the temperature level to low heat.
After the switch is pressed a third time, the
heated seat switch signal circuit of the rear door
module is again momentarily grounded, indicating
a heat off command. The rear door module
then sends out a SBI message to the DDM, indicating
the heat off command. The DDM then
sends out a Class 2 message to the RIM, indicating
the heat off command. The RIM again
momentarily sends a 35-millisecond one-shot
pulse signal that is pulled low through the heated
seat switch signal circuit of the heated seat module,
indicating the heat off command. In response
to this signal, the heated seat module then
removes the battery voltage from the seat heating
elements, turning off the heated seats.
Rear Heated Seat Switch
Indicators
When the heated seat is off and the rear heated
seat switch is pressed once, the heated seat temperature
is set to high heat. The rear door module
applies battery positive voltage through the
heated seat high temperature indicator control circuit
to the heated seat switch, illuminating the
high temperature indicator. When pressed a second
time, the heated seat temperature is set to low
heat. The rear door module the applies battery
positive voltage through the heated seat low temperature
indicator control circuit to the heated
seat switch, illuminating the low temperature
indicator. After the switch is pressed a third time,