Heater Control Circuit Inspection

Check for short circuit in Heater line
1. Ignition "OFF"
2. Disconnect front HO2S harness connector.
3. Measure resistance between terminals 6 and 1,2,3,4,5 of the HO2S harness connector
  Specification : Infinite
  
  Fig 1: Measuring Resistance Between Terminals 6 And 1,2,3,4,5 Of HO2S Harness Connector
Check for heater control circuit
1. Ignition "ON" & Engine "OFF"
2. Measure voltage between terminal 6 of the HO2S harness connector and chassis ground
  Specification : Approx.4.5V
Fig 2: Measuring Voltage Between Terminal 6 Of HO2S Harness Connector And Chassis Ground
Check for heater power circuit
1. Measure voltage between terminal 5 of the HO2S harness connector and chassis ground
  Specification : Battery voltage
Fig 3: Measuring Voltage Between Terminal 5 Of HO2S Harness Connector And Chassis Ground
Is the measured data within specification?
YES
- Check for open or short circuit in HO2S harness connector. Refer to "SIGNAL WAVEFORM & DATA " procedure in "General Information". Repair as necessary and go to "VERIFICATION OF VEHICLE REPAIR " procedure
NO
- Repair as necessary and go to "VERIFICATION OF VEHICLE REPAIR " procedure