Coolant Temperature / Trionic T7

Coolant Temperature

Coolant Temperature:

The coolant temperature gauge gives the driver information on engine coolant temperature.

The main instrument unit receives information from the temperature sensor, which is located on the left-hand side of the cylinder head and is in contact with the engine coolant. The sensor is NTC type. The main instrument unit measures the engine coolant temperature by supplying the sensor with 5 V from pin 15 (k22) through an integrated 680 ohm resistor. The sensor is grounded via main instrument unit pin 7 (K22). The voltage across the resistor in the main instrument unit is proportional to the engine coolant temperature. Information on the current engine coolant temperature is sent on the bus.

The coolant temperature gauge's scale is divided into 5 fixed breakpoints. The main instrument unit is programmed to move the gauge needle to the fixed breakpoints at certain specific temperatures to give a steady reading at normal coolant temperatures. The following breakpoints are programmed in the main instrument unit (factory setting):

Gauge needle: Coolant temperature
-into "blue" zone 30 °C (fixed value)
-out of "blue" zone 50 °C
-into "horizontal" position 80 °C
-out of "horizontal" position 115 °C
-into "red" zone 129 °C
-out of "red" zone 130 °C (fixed value)

Diagnostics
A break/short circuit generates diagnostic trouble code B1715 and the coolant temperature sensor bottoms.

Coolant Temperature, Trionic T7

Coolant Temperature, Trionic T7:

The coolant temperature gauge gives the driver information on engine coolant temperature. The main instrument unit controls the coolant temperature gauge and supplies it with current.

The temperature sensor is connected to the Trionic T7 which continuously sends coolant temperature information on the bus. The main instrument unit obtains coolant temperature information via the bus.

The coolant temperature gauge's scale is divided into 5 fixed breakpoints. The main instrument unit is programmed to move the gauge needle to the fixed breakpoints at certain specific temperatures to give a steady reading at normal coolant temperatures. The following breakpoints are programmed in the main instrument unit (factory setting):

Gauge needle: Coolant temperature
-into "blue" zone 30 °C (fixed value)
-out of "blue" zone 50 °C
-into "horizontal" position 80 °C
-out of "horizontal" position 115 °C
-into "red" zone 129 °C
-out of "red" zone 130 °C (fixed value)

Diagnostics
A break/short circuit generates diagnostic trouble code B1715 and the coolant temperature sensor bottoms.