Dodge Durango

 Service Manual

Fuel System » Fuel injection system » Description and operation
Oxygen sensor heater relays-pcm output

DESCRIPTION

The 2 oxygen (O2) sensor heater relays (upstream and downstream) are located in the Powertrain Distribution Center (PDC).

OPERATION

Engines equipped with the California (NAE) Emissions Package use four O2 sensors.

Two of the four sensor heater elements (upstream sensors 1/1 and 2/1) are controlled by the upstream heater relay through output signals from the Powertrain Control Module (PCM).

The other two heater elements (downstream sensors 1/2 and 2/2) are controlled by the downstream heater relay through output signals from the PCM.

To avoid a large simultaneous current surge, power is delayed to the 2 downstream heater elements by the PCM for approximately 2 seconds.

Powertrain control module (pcm)

Modes of operation

Automatic shutdown (asd) relay sense-pcm input

Battery voltage-pcm input

Brake switch-pcm input

Engine coolant temperature sensor-pcm input

Five volt sensor supplies-primary and secondary

Ignition circuit sense-pcm input

Intake manifold air temperature sensor-pcm input

Manifold absolute pressure (map) sensor-pcm input

Oil pressure sensor-pcm input

Oxygen sensor (o2s)-pcm input

Power grounds

Power steering pressure switch- pcm input

Sensor return-pcm input

Throttle position sensor (tps)-pcm input

Vehicle speed and distance-pcm input

Auto shutdown (asd) relay-pcm output

Ccd bus (+/-) circuits-pcm outputs

Data link connector-pcm input and output

Fuel injectors-pcm output

Fuel pump relay-pcm output

Idle air control (iac) motor-pcm output

Oxygen sensor heater relays-pcm output

Radiator cooling fan relay-pcm output

Throttle body