Buick Repair Questions? Ask a Mechanic for Answers ASAP
No heat at all, the lights come on on both the driver and passenger side but nothing happens. Seats stay cold.
It sounds like more than just switches so let me do some poking around. Can I get back to you in an hour or so? Maybe less.
HEATED SEATS DESCRIPTION AND OPERATION The driver and front passenger heated seats each consist of the following components.
The driver door module (DDM), passenger door module (PDM), and the rear integration module (RIM) are also involved in the operation of the heated seats.Power And Ground Battery positive voltage is supplied to both front heated seat modules from the rear fuse block IGN 3 Fuse. This allows the heated seats to operate only when the ignition in the ON position. Battery positive voltage is also supplied at all times to the heated seat modules from the rear fuse block; HTDST LF Fuse for the left heated seat module, or, HTDST RF for the right heated seat module. Both modules are grounded through the module ground circuits to G301.Temperature Regulation The heated seat system is designed in order to warm the seat cushion and seat back to approximately 42°C (107.6°F) when in the high heat position, and 37°C (98.6°F) when in the low heat position. The heated seat module monitors the seat temperature through the temperature sensor signal circuit and the temperature sensor (thermistor) that is located in the seat cushion. The temperature sensor is a variable resistor, it's resistance changes as the temperature of the seat changes. When the temperature sensor resistance indicates to the heated seat module that the seat has reached the desired temperature, the module opens the ground path of the seat heating elements through the heated seat element control circuit. The module will then cycle the element control circuit open and closed in order to maintain the desired temperature.Heated Seat Switch The driver and passenger heated seats are controlled by separate heated seat switches. Both heated seat switches are grounded through a ground circuit provided by the associated door control module. When the heated seat switch is pressed, the heated seat switch signal circuit of the door control module is momentarily grounded indicating either a high, low, or heat off command.Heated Seat Operation When the driver heated seat switch is pressed, the driver door module (DDM) sends a class 2 message to the rear integration module (RIM) indicating the driver heated seat command. In response to this signal, the RIM momentarily sends a one shot pulse signal that is pulled low through the heated seat high/low signal circuit to the heated seat module. The heated seat module then applies or removes battery positive voltage through the element supply voltage circuit to the seat heating elements.When the passenger heated seat switch is pressed, the passenger door module (PDM) sends a simple bus interface (SBI) message to the DDM indicating the passenger heated seat command. The DDM then sends a class 2 message to the RIM indicating the passenger heated seat command. In response to this signal, the RIM momentarily sends a 35 millisecond one shot pulse signal that is pulled low through the heated seat high/low signal circuit to the heated seat module. The heated seat module then applies or removes battery positive voltage through the element supply voltage circuit to the seat heating elements.LED Temperature Indicators When the heated seat is off and the heated seat switch is pressed once, the heated seat module will set the heated seat temperature to high heat. The door module then applies battery positive voltage through the high temperature indicator control circuit to the heated seat switch illuminating the high temperature indicator. When pressed again, the heated seat temperature is then set to low heat and the door module applies battery positive voltage through the low temperature indicator control circuit to the heated seat switch illuminating the low temperature indicator. After a third press of the heated seat switch, the door module removes battery positive voltage from the heated seat switch low temperature indicator, and the heated seat module removes the battery voltage from the seat heating elements. The heated seat module will also turn off the heated seats whenever the ignition switch has been turned to the OFF position.Load Management The ON/OFF status of the heated seats is reported to the RIM through the status output signal circuit of each heated seat module. During Load Shed Level 1, the RIM recognizes the heated seat status signal as active, and will cycle the heated seat operation 16.0 seconds ON and 4.0 seconds OFF. During Load Shed Level 2, the RIM will signal the heated seat module to deactivate the heated seat operation, and the door modules will turn off the appropriate heated seat switch temperature indicators.
Bulletin No.: 05-08-50-003A
Date: December 13, 2005
This bulletin is being revised to add models (2005 Chevrolet Corvette, 2002-2003 Oldsmobile Aurora) and remove the 2005 Cadillac STS. Please discard Corporate Bulletin Number 05-08-50-003 (Section 08 - Body & Accessories).
Some customers may comment that the heated seat function is inoperative again, one week or less after repair for the same concern was completed. The technician may have previously replaced the seat heater element and heated seat control module assembly, and the new module may be inoperative.
Electrostatic discharge from the seat may cause the heated seat control module to become inoperative.
Replace the heated seat module with the redesigned heated seat control module assembly, P/N 10399538.
Bulletin No.: 01-08-50-012B
Date: March 31, 2005
This bulletin is being revised to update the model year information. Please discard Corporate Bulletin Number 01-08-50-012A (Section 08-Body and Accessories).
Some customers may comment that the front seat assembly heat function is not operating properly.
This condition may be due to a non-functioning heat element in the front heated seat cushion or back trim cover.
Front Seat Heater Package Installation Procedure
Prior to installation, connect all of the components (elements) of the Front Seat Heater Package together and measure the resistance values. Refer to the applicable illustration shown for element connection information.
So, what I've provided for you here is a summary of how the system operates so you have an idea what is included in the system , & how it manages power.
The following two bulletins pertain to the two most common issues with these systems and they are the control modules, & the heater elements themselves. So you can see it is very important that you sit in BOTH seats & test the functionallity of them before condemming any parts. Now I will provide you with the diagnostic flow chart for the seat heaters. Do you have a scan tool & DVOM to measure voltage? If not, this job would best be suited for a Service Station that can perform these services.
The numbers below refer to the step numbers on the diagnostic table.