Many malfunctions in the electrical system are caused by poor harness and terminals.

Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.

Thoroughly check all connectors (and connections) for looseness, bending, corrosion, contamination, deterioration, and/or damage.

Has a problem been found?

	▶ Repair as necessary and then go to "Verification of Vehicle Repair" procedure.
	▶ Go to "Power Circuit Inspection" procedure.

Ignition switch "OFF"

Refer to "Shop Manual" and disconnect downstream lambda sensor connector.

Ignition switch "ON"

Measure the voltage between Pin No. 2 (Heater Power) terminal of downstream lambda sensor harness connector and chassis ground.

Is the measured value within specification?

	▶ Go to " Control Circuit Inspection " procedure.
	▶ Inspect and repair open or short in circuit, and then go to "Verification of Vehicle Repair" procedure.

Ignition switch "OFF"

Refer to "Shop Manual" and disconnect downstream lambda sensor connector.

Connect VMI to GDS and set up the Oscilloscope.(2 Channel):

Channel A (+) : Pin No. 5 (Heater Control) terminal (Downstream Lambda Sensor Harness Connector)

Channel A (-) : Ground

Ignition switch "ON"

Fig.1) Lambda sensor heater control pull-up signal waveform

Is the measured resistance within specification ?

	▶ Go to "Component Inspection" procedure.
	▶ Inspect and repair open or short in circuit, and then go to "Verification of Vehicle Repair" procedure.