9000 CDE V6-2962cc 3.0L DOHC (B308) (1995)
/Page-1904001.png)
Exhaust System Temperature Indicator: Description and Operation
Cars for certain markets are equipped with a monitoring system for catalytic converter overheating.
The system consists of:
^
Temperature sensor 417
^
Electronic relay 416
^
Warning lamp 47L
When the three-way catalytic converter temperature rises to between 800°C and 850°C, the warning lamp lights up and remains alight until the
temperature drops by about 10°C.
When current (+15 circuit) is applied to relay pin 1, the warning lamp is grounded and lights up for about 3 seconds. The lamp does not light up again
unless the temperature of the three way catalytic converter exceeds the limit value.
As the temperature rises, the current between pins 3 and 4 of the temperature sensor changes. When the change in the resistance of the sensor is
sufficiently large, the relay function is activated and the warning lamp lights up.
Similarly, the warning lamp goes out when the temperature drops or when the supply current (+15 circuit) is broken, i.e. when the ignition is switched
off.
