Heated Seat Module - Operation

OPERATION

The Heated Seat Module (HSM) controls the heated seat system. The HSM is secured to a mounting bracket located under the front passenger seat. The HSM responds to heated seat switch messages and ignition switch status inputs by controlling the 12v output to the seat heating elements through integral solid-state relays.

When either of the front heated seat switches are pressed, the A/C-heater control sends a message via the Controller Area Network (CAN) data bus to the HSM, signaling the module to energize the heating elements for the selected front seat. When equipped with rear heated seats, when either of the rear heated seat switches are pressed, a request signal is sent to the HSM over a hard-wired circuit, to signal the module to supply power to the heating elements for the selected rear seat.

The HSM energizes the integral solid-state relays that supply battery current to the heating elements. Heated seats turn off after 45 minutes of continuous operation. If high-level heating is selected, the control system will remain at the high level for 20 minutes and then drop to the low level. At that time, the number of illuminated LEDs in the respective switch change from two to one, indicating the temperature change.

The heated seat system operates on battery current received through a fused ignition Run circuit, so that the system will only operate when the ignition switch is in the On position. The heated seat system will turn off automatically whenever the ignition switch is turned to any position except On. With a heated seat on, if the ignition switch is turned to any position except On, the heated seat system will turn off and remain off, until the engine is restarted and a seat heated seat switch is pressed again.

The HSM is diagnosed using a scan tool and will automatically turn off the heating elements if it detects an open or low short in a heating element circuit Testing and Inspection.