Diagnostic Procedure

With the DRBIII®, read DTCs and record the related Freeze Frame data.

Is the Good Trip Counter displayed and equal to zero?

1. Yes --> Go To 2
2. No --> Refer to the SYMPTOM: INTERMITTENT CONDITION  Symptom (Diagnostic Procedure).

   Perform POWERTRAIN VERIFICATION TEST VER - 5 .

Ignition on, engine not running.

With the DRBIII®, actuate the ASD Fuel System test and observe the fuel pressure gauge.

Turn the ignition off.

Choose a conclusion that best matches your fuel pressure reading.

1. Below Specification
   1. Go To 3
2. Within Specification
   1. Go To 6
3. Above Specification
   1. Replace the fuel filter/pressure regulator.
   2. Perform POWERTRAIN VERIFICATION TEST VER - 5 .

Raise vehicle on hoist, and disconnect the fuel pressure line at the fuel pump module.

Install special 5/16 fuel line adapter tool #6539 or #6631 for 3/8 fuel line adapter, between the disconnected fuel line and the fuel pump module.

Attach a fuel pressure test gauge to the T fitting on tool #6539 or #6631.

Ignition on, engine not running.

With the DRBIII®, actuate the ASD Fuel System test and observe the fuel pressure gauge.

Is the fuel pressure within specification?

1. Yes --> Repair or replace fuel supply line as necessary.

   Perform POWERTRAIN VERIFICATION TEST VER - 5 .

2. No --> Go To 4

Remove the Fuel Pump Module and inspect the Fuel Inlet Strainer.

Is the Fuel Inlet Strainer plugged?

1. Yes --> Replace the Fuel Pump Inlet Strainer.

   Perform POWERTRAIN VERIFICATION TEST VER - 5 .

2. No --> Go To 5

1. Repair
   1. Replace the Fuel Pump Module.
   2. Perform POWERTRAIN VERIFICATION TEST VER - 5 .

Ignition on, engine not running.

With the DRBIII®, monitor all of the O2 Sensor voltage readings.

Is the voltage above 4.5 volts for all of the O2 Sensors?

1. Yes --> Go To 7
2. No --> Go To 13

Ignition on, engine not running.

With the DRBIII®, actuate the O2 Heater Test.

With the DRBIII®, monitor all O2 Sensor voltage readings for at least 2 minutes.

Does the voltage stay above 4.5 volts for any of the O2 Sensors?

1. Yes --> Replace the O2 Sensor that had the voltage reading above 4.0 volts.

   Perform POWERTRAIN VERIFICATION TEST VER - 5 .

2. No --> Go To 8

Is the voltage 0.92 of a volt or less with the Throttle closed?

1. Yes --> Go To 9
2. No --> Check for a binding throttle condition. If OK, replace the Throttle Position Sensor.

   Perform POWERTRAIN VERIFICATION TEST VER - 5 .

While monitoring the DRBIII®, slowly open and close the throttle.

Does the voltage increase and decrease smoothly?

1. Yes --> Go To 10
2. No --> Replace the Throttle Position Sensor.

   Perform POWERTRAIN VERIFICATION TEST VER - 5 .

Connect a Vacuum Gauge to a Manifold Vacuum source.

Start the engine.

Allow the engine to idle.

With the DRBIII® in Sensors, read the MAP Sensor vacuum value.

Is the DRBIII® reading within 1" of the Vacuum Gauge reading?

1. Yes --> Go To 11
2. No --> Replace the MAP Sensor.

   Perform POWERTRAIN VERIFICATION TEST VER - 5 .

With the DRBIII®, read the Engine Coolant Temperature Sensor value. If the engine was allowed to sit overnight (cold soak), the temperature value should be a sensible value that is somewhere close to the ambient temperature.

Start the Engine.

During engine warm-up, monitor the Engine Coolant Temperature value. The temp value change should be a smooth transition from start up to normal operating temp 82°C (180°F). The value should reach at least 82°C (180°F).

Did the Engine Coolant Temperature increase smoothly and did it reach at least 82°C (180°F)?

1. Yes --> Go To 12
2. No --> Replace the Engine Coolant Temperature Sensor.

   Perform POWERTRAIN VERIFICATION TEST VER - 5 .

AIR INDUCTION SYSTEM - must be free from leaks.

ENGINE VACUUM - must be at least 13 inches in neutral

ENGINE VALVE TIMING - must be within specifications

ENGINE COMPRESSION - must be within specifications

ENGINE EXHAUST SYSTEM - must be free of any restrictions or leaks.

ENGINE PCV SYSTEM - must flow freely

TORQUE CONVERTER STALL SPEED - must be within specifications

POWER BRAKE BOOSTER - no internal vacuum leaks FUEL - must be free of contamination

FUEL INJECTOR - plugged or restricted injector; control wire not connected to correct injector

Are there any engine mechanical problems?

1. Yes --> Repair as necessary.

   Perform POWERTRAIN VERIFICATION TEST VER - 5 .

2. No --> Refer to the SYMPTOM: INTERMITTENT CONDITION  Symptom (Diagnostic Procedure).

   Perform POWERTRAIN VERIFICATION TEST VER - 5 .

Disconnect the harness connector(s) of the O2 Sensor(s) that had a voltage reading below 4.5 volts in the previous step.

With the DRBIII®, monitor the O2 Sensor voltage reading(s).

Is the voltage above 4.5 volts for any of the O2 Sensors?

1. Yes --> Replace the O2 Sensor that had the voltage reading above 4.5 volts.

   Perform POWERTRAIN VERIFICATION TEST VER - 5 .

2. No --> Go To 14

Disconnect the PCM harness connectors.

Measure the resistance between ground and the O2 Sensor Signal circuit at the PCM harness connector.

Is the resistance below 100 ohms?

1. Yes --> Repair the short to ground in the O2 Sensor Signal circuit.

   Perform POWERTRAIN VERIFICATION TEST VER - 5 .

2. No --> Go To 15

If there are no possible causes remaining, view repair.

1. Repair
   1. Replace and program the Powertrain Control Module per Service Information.
   2. Perform POWERTRAIN VERIFICATION TEST VER - 5 .