Many malfunctions in the electrical system are caused by poor connection. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.

Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration,or damage.

Has a problem been found?

	▶ Repair as necessary and go to "Verification of Vehicle Repair" procedure.
	▶ Go to next procedure.

Ignition "OFF"

Disconnect auto defogger sensor and Connect A/C control Module main harness connector.

Ignition "ON"

Measure voltage between power terminal of auto defogger sensor harness connector and chassis ground.

Is the measured voltage within specification?

	▶ Go to Next procedure.
	▶ Check for open and short to ground in harness. ▶ Repair as necessary and then go to "Verification of Vehicle Repair" procedure.

Ignition "OFF"

Disconnect auto defogger sensor and A/C control Module main harness connector.

Measure resistance between sensor signalterminal of auto defogger sensor harness connector and chassis ground.

Is the measured resistance within specification?

	▶ Go to Next procedure.
	▶ Check for short to ground in control harness. ▶ Repair as necessary and then go to "Verification of Vehicle Repair" procedure.

Ignition "OFF"

Disconnect auto defogger sensor and A/C control Module main harness connector.

Measure resistance between sensor signal terminal of auto defogger sensor harness connector and sensor signal terminal of A/C control Module harness connector.

Is the measured value within specifications?

	▶ Substitute with a known-good auto defogger sensor and check for proper operation. If the problem is corrected, replace auto defogger sensor and then go to "Verification of Vehicle Repair" procedure.
	▶ Check for open in harness. ▶ Repair as necessary and then go to "Verification of Vehicle Repair" procedure.