RAM 1500 Truck 4WD V8-5.9L VIN Z (2002)
Oxygen Sensor Relay: Description and Operation
Oxygen Sensor Heater Relay:
If the vehicle is equipped with 4 oxygen sensors, a separate oxygen sensor relay is used to supply voltage to the sensor heating elements. This particular
relay is used only for the 1/2 and 2/2 downstream sensors. Voltage for the other 2 sensor heating elements is supplied directly from the ASD relay. Refer
to Wiring Diagrams to determine which relay is used. See: Diagrams/Electrical Diagrams
To avoid the large simultaneous current surge needed to operate all 4 sensors, power is delayed to the 2 downstream heater elements by the PCM for
approximately 2 seconds.
Oxygen Sensor Heaters/Heater Relays:
Depending on the emissions package, the heating elements within the sensors will be supplied voltage from either the ASD relay, or 2 separate oxygen
sensor relays. Wiring Diagrams to determine which relays are used.See: Diagrams/Electrical DiagramsApplications and ID.
