SZM Monitoring Of Seat Heating

Battery Voltage:  The SZM switches current supply to the heating elements off when battery voltage drops below 11.4 volts. However, the heating stage LEDs remain on. Regulated output current resumes when battery voltage raises above 12.2 volts for more than 5 seconds.

SZM Internal Temperature:  The power output stages for the seat heating elements generate a considerable amount of heat when in stage 1 operation. The SZM monitors it's own internal temperatures and reduces the heating output when internal temperatures rise to a temperature of 185°F or switches it off completely above 203°F.

As with battery voltage monitoring, the heating stage LEDs remain on when these temperatures are exceeded.

Fault Monitoring:  The SZM monitors the temperature sensors and heating mats for faults. Detected faults are stored in the SZM. Fault Symptom Troubleshooting in conjunction with stored faults will initiate the diagnostic paths using the DIS/MoDiC.

The following faults can be recognized:

• Shorts or opens in the wiring circuits.
• Shorts or opens in the temperature sensors
• Open in heating element.

If a short is detected in the temperature sensor, the seat heating is switched off to prevent overheating. The Stage LEDs are also switched off with this fault present.