C 350 (204.056) V6-3.5L (272.961) (2008)
Coolant Temperature Sensor/Switch (For Computer): Description and Operation
GF07.04-P-6043CY Component Description For The Coolant Temperature Sensor
- up to model year 08
Component Identification
The temperature sensor is located at the rear on the left cylinder head.
Task
The temperature sensor detects the coolant temperature and transmits a corresponding voltage signal to the ME-SFI [ME] control unit (N3/10).
Design
The temperature sensor consists of a very rapidly responding NTC resistor and a 2-pin connector. The housing bottom section which is inserted in the
cylinder head is made out of metal.
The connection assignment (polarity) of pin 1 and 2 is arbitrary.
Function
The NTC resistor integrated in the temperature sensor alters its electrical resistance in line with the coolant temperature. The ME-SFI [ME] control unit
applies a sensor voltage of 5 V and evaluates the signal voltage in accordance with the coolant temperature.
The signal voltage is plausible between 0.1 V to 4.93 V, otherwise a fault is identified and a substitute value taken by the ME-SFI [ME] control unit from
a stored temperature model.
NTC means " Negative Temperature Coefficient", which means: the electrical resistance reduces for an increasing temperature (NTC thermistor).
Example:
Coolant temperature
Resistor
20 °C
3090 ohms ±5%
80 °C
320 ohms ±5%
The NTC resistor is supplied with a 5 V voltage by the ME-SFI [ME] control unit via a series resistor with 1470 ohms ±1%. Following a short- circuit to
battery voltage or sensor voltage without series resistor, the temperature sensor is defective.