Normal Operation

The heated seat module receives ignition voltage on circuit CBP35, battery voltage on circuit SBP18 and ground on circuit GD139. When the driver or passenger heated seat button is pressed, a momentary ground signal is sent on the driver or passenger request circuit to turn the heated seat system on or off. The heated seat module monitors temperature sensors contained within the cushion heater mats. The temperature sensors share return circuit RHS05 to the heated seat module. If the temperature sensor return circuit opens (resistance greater than 300,000 ohms), the heated seat module will disable the outputs to both seats.

The Front Controls Interface Module (FCIM) (with navigation), HVAC module and heated seat module must be communicating correctly for the system to operate correctly. PIDs are available to check heated seat switch operation in the FCIM  (with navigation) and HVAC module (with and without navigation).

Normal heat cycle may require several minutes to initially warm the seat. The seat should be occupied to correctly test for normal operation. Temperature measuring devices do not provide an accurate method for testing heated seat operation as surface temperatures are subject to human and environmental characteristics. Correct testing requires heater mat resistance measurements which have tight tolerances affecting the length of time for the heater mats to reach maximum operating temperature.

The heated seat module does not report DTCs. If a fault is detected, the module will disable the affected seat(s) and indicator(s). After the fault is corrected, the heated seat module needs to be reset by cycling the ignition.

This pinpoint test is intended to diagnose the following: 

• Fuse(s)
• Wiring, terminals or connectors
• Medium Speed Controller Area Network (MS-CAN) fault
• FCIM  (if equipped)
• Heated seat module
• HVAC module