Oxygen Sensor 2 Heater, Checking
Oxygen Sensor 2 Heater, Checking
The following procedure is used to diagnose Oxygen Sensor (O2S) 2 Heater (Z28) for Heated Oxygen Sensor (HO2S) 2 (G108) which is controlled by the Engine Control Module (ECM) 2 (J624).
• When servicing electrical harness connector terminals for the Heated Oxygen Sensors, use only gold-plated terminals.
Special tools, testers and auxiliary items required
• Multimeter.
• Wiring diagram.
Test requirements
• Heated Oxygen Sensor (HO2S) Circuit Breaker (S73 ) OK.
• Battery voltage at least 12.5 volts.
• All electrical consumers such as, lights and rear window defroster, switched off.
• Vehicles with automatic transmission, shift selector lever into position " P" or "N".
• A/C switched off.
• Ground (GND) connections between engine/transmission/chassis OK.
• Ignition switched off.
Test procedure
- Perform a preliminary check to verify the customers complaint. Refer to => [ General Diagnosis ] General Diagnosis.
Start diagnosis
- Raise the vehicle.
- Disconnect the Heated Oxygen Sensor (HO2S) 2 ( G108) electrical harness connector- 4 -.
Checking internal resistance
- Using a multimeter, check the Heated Oxygen Sensor (HO2S) 2 (G108) terminals 3 to 4 for resistance.
Specified value: 2.5 to 10.0 ohms (at approx. 20° C)
If the specification was not obtained:
- Replace Heated Oxygen Sensor (HO2S) 2 (G108). Refer to Fuel Injection and Ignition Repair Information.
If the specification was obtained:
Checking voltage supply
Crank the engine.
- Using a multimeter, check the Heated Oxygen Sensor (HO2S) 2 (G108) electrical harness connector terminal 4 to Ground (GND) for voltage.
Specified value: Battery voltage.
Switch the ignition off.
If the specification was not obtained:
- Check the electrical harness connector for damage, corrosion, lose or broken terminals.
- Check the wiring from the Heated Oxygen Sensor (HO2S) 2 (G108) electrical harness connector terminal 4 to the Engine Component Power Supply Relay (J757) socket 2/87 for a short circuit to each other, Ground (GND), or an open circuit.
- If necessary, repair the faulty wiring connection.
If the specification was obtained:
Checking Ground (GND) activation
If the manufacturers test box is being used. Perform the following step.
- Install the test box. Refer to Fuel Injection and Ignition Repair Information.
If the manufacturers test box is not being used. Perform the following step.
- Remove the Engine Control Module (ECM) 2 (J624 ). Refer to => [ Engine Control Module 1, Removing and Installing ] Engine Control Module 1, Removing and Installing.
- Using a multimeter, check the Heated Oxygen Sensor (HO2S) 2 (G108) electrical harness connector to the Engine Control Module (ECM) 2 (J624) electrical harness connector T94a for an open circuit.
Specified value: 1.5 ohms max.
If the specification was not obtained:
- Check the wiring for a short circuit to each other, Battery (+), Ground (GND) or an open circuit.
- If necessary, repair the faulty wiring connection.
If no malfunction is detected in the wiring and if the voltage supply was OK:
- Replace the Engine Control Module (ECM) 2 (J624 ). Refer to => [ Engine Control Module 1, Removing and Installing ] Engine Control Module 1, Removing and Installing.
Final procedures
After repair work, the following work steps must be performed in the following sequence:
1. Check the DTC memory. Refer to => [ Diagnostic Mode 03 - Read DTC Memory ] Diagnostic Mode 03 - Read DTC Memory.
2. If necessary, erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Mode 04 - Erase DTC Memory.
3. If the DTC memory was erased, generate readiness code. Refer to => [ Readiness Code ] Monitors, Trips, Drive Cycles and Readiness Codes.
- End of diagnosis.