Automatic Transmission: Maintenance Saab 9-5 I рестайлинг 2

Transmission Fluid Temperature Sensor

The oil temperature sensor mounted on the valve housing gives the control module information on the current oil temperature. The sensor is a NTC-type (Negative Temperature Coefficient).

The control module measures the temperature of the gearbox oil by supplying the sensor with +5 V through a 1 kOhm resistor integrated into the control module, and out via pin 21 (B). When the temperature of the oil rises the resistance in the NTC resistor decreases. This means that the flow increases and causes a voltage drop across the NTC resistor measured by TCM.

The sensor is grounded in pin 31 (B).

The control module uses the oil temperature for the following purposes

Scheme 206

1. Control engagement and disengagement of lock-up. There will be no lock-up at temperatures below 20°C and no lock-up slip at temperatures under 40°C.
2. To control the different temperature programs.
3. To warn the driver of overheated transmission.