Diagnostic Test

1) GOOD TRIP INDICATED
NOTE: Check for contaminants that may have damaged the O2 Sensor: contaminated fuel, unapproved silicone, oil and coolant.

Turn the ignition on.

With the scan tool, read DTCs.

Does the Good Trip Indicator display NO?

Yes
1. Go To 2).
No
1. Refer to the INTERMITTENT CONDITION diagnostic procedure.
2. Perform the POWERTRAIN VERIFICATION TEST. (Refer to STANDARD PROCEDURE - POWERTRAIN VERIFICATION TEST) .
2) O2 SENSOR GROUND CIRCUIT OPEN

Fig 1: MEASURING RESISTANCE OF THE O2 SENSOR GROUND CIRCUIT
Courtesy of DAIMLERCHRYSLER CORP.

Turn the ignition off.

Disconnect the O2 Sensor harness connector

Disconnect the PCM harness connector.

Measure the resistance of the O2 Sensor ground circuit from the O2 Sensor harness connector and the PCM harness connector.

Is the resistance below 5.0 ohms?

Yes
1. Go To 3).
No
1. Repair the open O2 Sensor ground circuit.
2. Perform the POWERTRAIN VERIFICATION TEST. (Refer to STANDARD PROCEDURE - POWERTRAIN VERIFICATION TEST) .
3) O2 SENSOR OPERATION
Turn the ignition off.

Disconnect the O2 Sensor harness connector.

Turn the ignition on.

Connect a test light to battery voltage, probe the O2 Sensor Signal circuit in the O2 Sensor harness connector.

With the scan tool, read the O2 Sensor voltage.

Is the voltage above 1.0 volts?

Yes
1. Replace the O2 Sensor.
2. Perform the POWERTRAIN VERIFICATION TEST. (Refer to STANDARD PROCEDURE - POWERTRAIN VERIFICATION TEST) .
No
1. Go To 4).
4) O2 SENSOR SIGNAL OPEN

Fig 2: MEASURING RESISTANCE OF THE O2 SENSOR SIGNAL CIRCUIT
Courtesy of DAIMLERCHRYSLER CORP.

Turn the ignition off.

Disconnect the O2 Sensor harness connector

Disconnect the PCM harness connector.

Measure the resistance of the O2 Sensor Signal circuit from the O2 Sensor harness connector and the PCM harness connector.

Is the resistance below 5.0 ohms?

Yes
1. Go To 5).
No
1. Repair the open O2 Sensor Signal circuit.
2. Perform the POWERTRAIN VERIFICATION TEST. (Refer to STANDARD PROCEDURE - POWERTRAIN VERIFICATION TEST) .
5) O2 SENSOR GROUND CIRCUIT VOLTAGE DROP
NOTE: Ensure the voltmeter leads meet the terminals in the connector and that there is good terminal to wire connection.

NOTE: Ensure the voltmeter leads are connected for positive polarity

Perform a voltage drop test by backprobe between the O2 Sensor ground circuit at the O2 Sensor harness connector and PCM harness connector.

Start the engine.

Allow the engine to idle.

Is the voltage below 0.10 volt?

Yes
1. Go To 6).
No
1. Repair the high resistance on the O2 Sensor ground circuit.
2. Perform the POWERTRAIN VERIFICATION TEST. (Refer to STANDARD PROCEDURE - POWERTRAIN VERIFICATION TEST) .
6) O2 SENSOR SIGNAL CIRCUIT VOLTAGE DROP
NOTE: Ensure the voltmeter leads meet the terminals in the connector and that there is good terminal to wire connection.

NOTE: Ensure the voltmeter leads are connected for positive polarity

Perform a voltage drop test backprobe between the O2 Sensor Signal circuit at the O2 Sensor harness connector and PCM harness connector.

Start the engine.

Allow the engine to idle.

Is the voltage below 0.10 volt?

Yes
1. Go To 7).
No
1. Repair the high resistance on the O2 Sensor Signal circuit.
2. Perform the POWERTRAIN VERIFICATION TEST. (Refer to STANDARD PROCEDURE - POWERTRAIN VERIFICATION TEST) .
7) PCM
NOTE: Before Continuing: Disconnect the PCM harness connector and check the related wiring terminals for corrosion, damage or terminal push out. Repair as necessary.

Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.

If there are no possible causes remaining, view repair.

Repair
1. Replace and program the Powertrain Control Module in accordance with the Service Information. (Refer to STANDARD PROCEDURE - PCM/ECM/SKREEM PROGRAMMING) .
2. Perform the POWERTRAIN VERIFICATION TEST. (Refer to STANDARD PROCEDURE - POWERTRAIN VERIFICATION TEST) .