RAM 2500 Truck 2WD L6-359 5.9L DSL Turbo VIN D FI (1997)
Intake Air Temperature Sensor: Description and Operation
Fig. 3 Air Temperature Sensor Location - Diesel
DESCRIPTION
This pin provides an input signal to the Powertrain Control Module (PCM). The intake manifold air temperature sensor is a variable, thermistor
type.
LOCATION
The sensor is located on the top of the intake manifold and to the rear of the intake manifold air heater.
OPERATION
The intake manifold air temperature sensor reacts to temperature changes. At cold air temperatures, its resistance is high. As temperatures increase,
its resistance will decrease. The air temperature sensor element extends into the intake manifold air stream.
As the temperature of the air-fuel stream in the manifold varies, the sensor resistance will change. This will result in a different input voltage to the
PCM.
PURPOSE
It provides an input voltage to the PCM indicating intake manifold air temperature. The input from this sensor is used by the PCM to determine if
and how long to activate the intake manifold air heater relays. When the relays are activated, current will flow through the relays to the intake
manifold air heater.
Also refer to Intake Manifold Heater Relays-PCM Pin #15-PCM Output for additional information. See: Computers and Control Systems/Description
and Operation/Functional Operation/Inputs and Outputs/Outputs/Intake Manifold Air Heater Relays
CIRCUIT OPERATION
The intake air temperature sensor provides an input to the Powertrain Control Module (PCM) on circuit K21. Circuit K21 connects to cavity A15
of the PCM.
From circuit K21, the intake air temperature sensor draws voltage from the PCM. The sensor is a variable resistor. As intake air temperature
changes,the resistance in the sensor changes, causing a change in current draw.
The PCM provides a ground for the intake air temperature sensor signal (circuit K21) through circuit K4. Circuit K4 connects to cavity A4 of the
PCM.
