2000 3.2 TL Heated Seat Replacement

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.

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

Do you know what B - body DTC -diagnostic trouble code are ?
DTC B2425 Driver Seat Heater Circuit
DTC B2435 Driver Seat Back Heater Sensor Circuit
DTC B3941 Front Seat Heaters Circuit

Heated Seat Always On
Step
Action
Yes
No
Schematic Reference: Driver Seat Schematics and Passenger Seat Schematics
Connector End View Reference: Power Seat Connector End Views
1
Did you perform the Diagnostic System Check - Vehicle?
Go to Step 2
Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
2
Operate the heated seat system.
Does the system operate normally?
Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems
Go to Step 3
3
Install a scan tool.
Display the Heated Seat Status parameter in the driver seat module Input/Output data list.
Start the engine.
Does the scan tool display the Heated Seat Status parameter as Off?
Go to Step 6
Go to Step 4
4
Display the Heated Seat Mode parameter in the door module Inputs data list.
Does the scan tool display the Heated Seat Mode parameter as OFF?
Go to Step 6
Go to Step 5
5
Turn OFF the ignition.
Disconnect the heated seat switch connector to the door module.
Start the engine.
Does the scan tool display the Heated Seat Mode parameter as OFF?
Go to Step 7
Go to Step 8
6
Replace the driver seat module. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.
Is the repair complete?
Go to Step 9
--
7
Replace the heated seat switch. Refer to Front Seat Heater Switch Replacement .
Is the repair complete?
Go to Step 9
--
8
Replace the door module. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.
Is the repair complete?
Go to Step 9
--
9
Operate the system in order to verify the repair.
Did you correct the condition?
System OK
Go to Step 3


your best bet , have a qualified repair shop diagnose the problem

Not a fuse issue , more then likely a burnt heating element in the seat , happens all the time .
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

The control module have a Battery voltage supply , the module supply's voltage to the seat heating elements .
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.

Your best bet , take it to a qualified repair shop.

Electronic's ! drivers Power seat module , driver door module . Do you know anything about automotive electronic's ?

The heated seat module (MSM) controls heated seat operation for both the driver and passenger seats. There are 2 modes of operation available for heated seats; both the seat cushion and seat back heat, or seat back only heat. When a heated seat temperature signal request is received, the MSM will activate both the seat cushion and seat back heating elements. When the heated seat BACK ONLY mode button is pressed once the MSM will deactivate the seat cushion heating element and leave the seat back heating element ON.
The adjustable pedal system is controlled by the memory seat module (MSM).
your best bet , have a qualified repair shop check it out ! Could have DTC'S - diagnostic trouble codes in door module , BCM etc...

You have probably burnt up the element as it is a 17 year old seat now. The elements are replaceable, but the labor is pretty spendy. To test it you will need a multimeter to check for continuity across the connectors that go to the seat heating elements and check for voltage at the car side of the connector. If you have 12v to one side of the connector and continuity to ground at the other side, and do not have continuity to the seat side between the connectors, you know it is a bad element.

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
When there are modules involved in the operation of any componet that's acting up , the module's electronic's could be the culprit ! But without testing who's to say what the problem could be !
I would have it check for DTC'S
DTC B2425 or B2430
The driver and passenger seat heaters are controlled by the driver seat module. Power is supplied to the driver seat cushion and back heater elements through individual voltage supply circuits. Power is supplied to the passenger seat cushion and back heater elements through a common voltage supply circuit. All of the driver and passenger seat heater elements are grounded by the driver seat module through individual low side drive control circuits. The heater element control circuits are pulse width modulated to ground by the driver seat module in order to control the seat temperatures by regulating the current flow through the heater elements.
DTC B2435 or B2440
The driver seat module relies on inputs from thermistors installed 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 low reference circuit from the driver 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.
Install a scan tool.
Start the engine.
Turn the heated seat ON.
With a scan tool, observe the Heated Seat Sensor parameter in the data list for the driver seat module.
Does the scan tool indicate that the heated seat sensor parameter is within the specified range?
0.078-4.94 V

Heated Seats
This system allows the electrical heating of the front seats on passenger demand.
The components of the system are:

• the seat heating elements located in the seat cushion and backrest.
• the heated seat control switch, located on the seat side trim panel.
• temperature sensors located in the seat cushion heating elements.
• heated seat relay.

Do both front seat heaters not work ? Do you know how to test electrical circuits with voltmeter ?
PINPOINT TEST J: THE HEATED SEAT IS INOPERATIVE Test Step Result / Action to Take J1 CHECK HEATED SEAT SWITCH OPERATION

• Key in ON position.
• Press the heated seat switch on the driver and passenger seats.
• Are both heated seat switch indicators illuminated?

Yes
If both indicators illuminate, Go To Pinpoint Test K . If only one indicator illuminates, GO to J5 .

No
GO to J2 . J2 CHECK THE HEATED SEAT RELAY CIRCUITS

• Key in OFF position.
• Disconnect: Heated Seat Relay C3250 (located under the driver seat).
• Key in ON position.
• Measure the voltage at heated seat relay C3250-86, circuit 1003 (GY/YE), harness side and ground; and between C3250-30, circuit 566 (DG), harness and ground.
  
• Are the voltages greater than 10 volts?

Yes
GO to J3 .

No
REPAIR inoperative 1003 (GY/YE) or 566 (DG) circuit. TEST the system for normal operation. J3 CHECK HEATED SEAT RELAY GROUND CIRCUIT

• Key in OFF position.
• Measure the resistance between heated seat relay C3250-85, circuit 57 (BK), harness side and ground.
  
• Is the resistance less than 5 ohms?

Yes
GO to J4 .

No
REPAIR circuit 57 (BK). TEST the system for normal operation. J4 CHECK THE HEATED SEAT RELAY

• Install a fused jumper lead between heated seat relay 3250-30, circuit 566 (DG), harness side and heated seat relay C3250-87, circuit 1064 (YE/LB), harness side.
  
• Do both heated seat indicators illuminate when pressed?

Yes
INSTALL a new heated seat relay. TEST the system for normal operation.

No
REPAIR circuit 1064 (YE/LB) to switches. TEST the system for normal operation. J5 CHECK INOPERATIVE HEATED SEAT SWITCH INPUT

• Key in OFF position.
• Disconnect: Heated Seat Switch C320 (Driver) or C321 (Passenger) for the inoperative heated seat.
• Key in ON position.
• Measure the voltage between heated seat switch C320-2 (driver) or C321-2 (passenger), circuit 1064 (YE/LB), harness side and ground .
  
• Is the voltage greater than 10 volts?

Yes
GO to J6 .

No
REPAIR circuit 1064 (YE/LB). TEST system for normal operation. J6 CHECK CIRCUIT 57 (BK) FOR AN OPEN

• Measure the resistance between heated seat switch C320-4 (driver) or C321-4 (passenger), circuit 57 (BK), harness side and ground.
  
• Is the resistance less than 5 ohms?

Yes
INSTALL a new heated seat switch. TEST the system for normal operation.

No
REPAIR circuit 57 (BK). TEST the system for normal operation It's not that simple , being a fuse . It's probably the relay or the heating element .
PINPOINT TEST K: SEAT DOES NOT HEAT BUT THE HEATED SEAT INDICATOR ILLUMINATES WHEN PRESSED ? Does it ?
Your best bet would be to take to a qualified repair shop .
Do

MORE THAN LIKELY THE HEATING ELEMENT HAS MALFUNTIONED. ITS A PRETTY COMMON PROBLEM IN HEATED SEATS

Swap it with a relay you know to be good and see if it works again,pick a relay that is not important to the function of your car.

most likely you will be dealing with broken seat element. locate harness connector for heating element under seat and ck for power with test lite. just experienced same problem in a 2000 park ave

Could be that the wiring for the heater is broken, or that the heating element itself has been damaged. Has anyone knelt on the seat when reaching in to get something out of the car? Or has anyone stood on it (a child maybe)? Pressure like that can break the heaters and keep them from firing up.