A/F Sensor Heater Relay: Inspection

REMOVE RELAY BOX COVER
REMOVE A/F SENSOR HEATER RELAY (Marking: A/F HTR)

Fig 1: Removing A/F Sensor Heater Relay
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
INSPECT A/F SENSOR HEATER RELAY CONTINUITY
1. Using an ohmmeter, check that there is continuity between terminals 1 and 2.
  If there is no continuity, replace the relay.
2. Check that there is no continuity between terminals 3 and 5.
If there is continuity, replace the relay.

Fig 2: Inspecting A/F Sensor Heater Relay Continuity
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
INSPECT A/F SENSOR HEATER RELAY OPERATION
1. Apply battery voltage across terminals 1 and 2.
2. Using an ohmmeter, check that there is continuity between terminals 3 and 5.
If there is no continuity, replace the relay.
REINSTALL A/F SENSOR HEATER RELAY
REINSTALL RELAY BOX COVER

Fig 3: Inspecting A/F Sensor Heater Relay Operation
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002