Cadillac Repair Questions? Ask a Mechanic for Answers ASAP
Bulletin No.: 06-08-50-013
Date: November 09, 2006
The purpose of this bulletin is to provide dealers with information to help diagnose inoperative heated/cooled seats (seat cushion, seat back or both).
Both Seat Back AND Seat Cushion Heated/Cooled Functions Inoperative
Verify that connections to the heat/cool seat module (1), which is located under the passenger side seat, are fully seated.
The smaller 10- and 16-way connectors (2, 3) should have the blue CPA fully engaged.
The 12-way connector (4) should be inspected to make sure that it is fully seated.
Seat Back Heated/Cooled Functions Inoperative
Verify that the black 8-way connector (1) is fully engaged. To gain access this connector, remove the plastic seat back panel. The connector is located just above the blower.
Attempt to pull the mating connectors that go to the blower and seat back harness apart WITHOUT depressing the release lever. If the connector disengages, force the connectors together until a "click" is heard and the connectors can no longer be pulled apart without depressing the release lever.
Seat Cushion Heated/Cooled Functions Inoperative
Verify that the black 8-way connector (1) that connects the seat wiring harness to the blower takeout is properly seated. This connector is located under each seat and can be accessed from the rear underside of the seat.
Force the connectors together until a "click" is heard, and then attempt to disengage the connector without depressing the lever release. If you are unable to disconnect, a full connection has been attained.
HEATED/COOLED SEATS INOPERATIVE DIAGNOSTIC FAULT INFORMATION Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. See: Testing and Inspection\Initial Inspection and Diagnostic Overview\Diagnostic Starting Point - Vehicle CIRCUIT/SYSTEM DESCRIPTION The heated cooled seat system operation is controlled through the switch inputs of the HVAC control module. When a heated or cooled seat switch is pressed a GMLAN message is sent to the Memory Seat Module (MSM) indicating the switch is active. The MSM monitors the heated cooled seat switch inputs and determines the appropriate operating mode. When a heated or cooled seat function is activated the MSM will send a GMLAN message to the HVAC control module to illuminate the appropriate indicators and a PWM message to the Climate Control Seat Module (CCSM) to activate the appropriate heated cooled seat function. The CCSM controls heat/cool seat ventilation blowers located under the seat cushion and behind the seat back. The ventilation blowers are self contained electronic air conditioners consisting of a blower motor with an inlet air filter, thermal electric device (TED), temperature sensor, and waste air duct. The air flow from the blower is divided into 2 streams and directed across both sides of the TED, one side into vent passages through the seat foam and the other out the waste air duct. While the system is operating in either the heat or cool modes both heated and cooled air is generated as it passes across the TED. When voltage is applied to a TED, one side releases energy as heat, while the opposite side absorbs energy and gets cold. The supply voltage to the TEDs is controlled by the CCSM and the polarity determines which side gets hot or cool. When the polarity of the current flow to the TEDs is switched, the hot and cool sides of the TED reverse. The CCSM monitors the temperature of the air flow into the seat foam and continuously adjusts the blower speed and TED temperature by regulating the current flow through each component. The CCSMs rely on inputs from temperature sensors located in the ventilation blowers near the TEDs to control seat temperatures. The thermistors are 2 wire sensors supplied with a 5-volt referenced signal circuit and a low reference circuit from the CCSM. Resistance through the thermistors varies with temperature causing the heated seat sensor signal circuit voltage levels to decrease as the TED temperatures rise. DIAGNOSTIC AIDS The following conditions must be met in order to perform valid tests when diagnosing the climate control seat (CCS) system:
In hotter or colder climates where room temperature conditions of 70°F (21°C) may be unattainable, resistance values may read above the specified range. Use a heat gun or a blower to warm or cool the TED while measuring the resistance. The resistance values should slowly lower toward the specified range. Test for 0.9-10.0 ohms of resistance between the following heat control and cool control circuits.
PASSENGER HEATED/COOL SEAT CIRCUIT TEST
Test for 0.9-10.0 ohms of resistance between the following heat control and cool control circuits.