501-10 Seating: Description And Operation (page 12 of 14)

Rear Seat Heaters 

Rear Seat Heater Switches 

NOTE :  

 
The RH and LH rear seats support three integral heating elements, squab, back rest and bolster. The optional rear child 
booster seat also supports an integral seat-heating element. 
 
NOTE :  

 
The rear seat heaters are enabled when the ignition switch is position II, and operate at one of two temperature settings. 
With the first press of a rear seat heater switch the relative rear seat heat control module (RH or LH) adopts the higher 
temperature setting, supplies a power feed to the related rear seat heater elements and illuminates two amber LED's in 
the switch. At the second press of the switch the control module adopts the lower temperature setting and extinguishes 
one of the LED's. At the third press of the switch the control module de-energises the heater elements and extinguishes 
the second LED. The seat heaters remain on until selected off or the ignition is turned off. 
 
The rear seat heat control modules receive an input from a temperature sensor in RH and LH rear seats, and regulate the 
power feed of the heater elements to control the seat temperature at the appropriate temperature setting between 35 and 
45 °C (95 and 113 °F). The actual temperature settings vary with the type of seat covering, to allow for the different heat 
conduction properties of the different seat covering materials. 
 

DIAGNOSTICS 

The exchange of information between the diagnostic unit and the memory control module is via the CJB, which are 
interconnected via the hi-speed Controller Area Network (CAN) bus and LIN bus. There is a non-volatile memory 
(EEPROM) for saving detected errors. Its contents are not lost when the power supply is disconnected. Only the T4 
diagnostic tester can erase the error memory. 
 

CONTROL DIAGRAM 

Rear air conditioning variant shown 

The rear centre seat is not available with seat heating.