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Home >> Dodge and Ram >> 2003 >> Durango Base, 5.9 Z, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 15 (Engine Controls - Self Diagnostics - 4.7L) >> Diagnostic Tests >> DTC P0068: Manifold Pressure/Throttle Position Correlation - Vacuum Leak Detected >> Testing

DTC P0068: Manifold Pressure/Throttle Position Correlation - Vacuum Leak Detected: Testing

WARNING: This page is about a different car, the 2003 Dodge Dakota. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: Diagnose any TP sensor or MAP sensor component DTCs before continuing. If the P0501 No Vehicle Speed Signal is set along with this DTC, refer to the DTC P0501: VEHICLE SPEED SENSOR #1 PERFORMANCE  diagnostics before continuing. The throttle plate and linkage must be free from binding and carbon build up. Ensure the throttle plate is at the idle position.
  1. Ignition on, engine not running. With the DRBIII® scan tool, read DTCs and record the related freeze frame data. Is the Good Trip Counter displayed and equal to zero? If yes, go to next step. If no, see INTERMITTENT CONDITION  under SELF-DIAGNOSTIC SYSTEM.
    2. NOTE: This code is enabled on engines with a plastic intake manifold and is intended to shut down the engine if a large crack occurs. A large vacuum leak is most likely the cause of this DTC.
  2. Inspect the intake manifold for leaks and cracks. Inspect the power brake booster for any vacuum leaks. Inspect the PCV system for proper operation or any vacuum leaks. Inspect the MAP sensor for proper installation. Were any vacuum leaks found? If yes, repair the vacuum leak as necessary. If no, go to next step.
  3. Start the engine. With the DRBIII® scan tool, monitor the MAP sensor voltage. Snap the throttle. Does the MAP sensor voltage vary from below 2.0 volts at idle to above 3.5 volts at WOT? If yes, go to next step. If no, go to step  11.
  4. Ignition on, engine not running. With the DRBIII® scan tool, monitor the TP sensor voltage while slowly depressing the throttle pedal from the idle position to the wide open throttle position. Does the voltage start approximately at 0.8 volt and go above 3.5 volts with a smooth transition? If yes, see INTERMITTENT CONDITION . If no, go to next step.
    5. CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool (8815) to perform diagnosis.
  5. Turn the ignition off. Disconnect the TP sensor harness connector. Disconnect the PCM harness connectors. Measure the resistance of the (K7) 5-volt supply circuit from the TP sensor harness connector to the appropriate terminal of Miller Special Tool (8815). Is the resistance below 5.0 ohms? If yes, go to next step. If no, repair the TP sensor (K7) 5-volt supply circuit.
  6. Measure the resistance between ground and the (K7) 5-volt supply circuit at the TP sensor harness connector. Is the resistance above 100 k/ohms? If yes, go to next step. If no, repair the excessive resistance in the (K7) 5-volt supply circuit.
  7. Connect PCM harness connectors. Ignition on, engine not running. With the DRBIII® scan tool, monitor the TP sensor voltage. Connect a jumper wire between the (K22) TP signal circuit and the (K4) sensor ground circuit. Does the TP sensor voltage change from approximately 4.9 volts to below 0.5 of a volt? If yes, replace the TP sensor. If no, go to next step.
    NOTE: Remove the jumper wire before continuing.
    8. CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool (8815) to perform diagnosis.
  8. Turn the ignition off. Disconnect the PCM harness connectors. Measure the resistance of the (K22) TP sensor No. 1 signal circuit from the TP sensor harness connector to the appropriate terminal of Miller Special Tool (8815). Is the resistance below 5.0 ohms? If yes, go to next step. If no, repair the excessive resistance in the (K22) TP signal circuit.
  9. Measure the resistance between ground and the (K22) TP signal circuit in the TP sensor harness connector. Is the resistance above 100 k/ohms? If yes, go to next step. If no, repair the (K22) TP sensor signal circuit.
    10. CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool (8815) to perform diagnosis.
  10. Measure the resistance of the (K4) sensor ground circuit from the TP sensor harness connector to the appropriate terminal of Miller Special Tool (8815). Is the resistance below 5.0 ohms? If yes, go to step  17. If no, repair the excessive resistance in the (K4) sensor round circuit.
    11. CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool (8815) to perform diagnosis.
  11. Turn the ignition off. Disconnect the MAP sensor harness connector. Disconnect the PCM harness connectors. Measure the resistance of the (K6) 5-volt supply circuit from the MAP sensor harness connector to the appropriate terminal of Miller Special Tool (8815). Is the resistance below 5.0 ohms? If yes, go to next step. If no, repair the MAP excessive resistance in the (K6) 5-volt supply circuit.
  12. Measure the resistance between ground and the (K6) 5-volt supply circuit at the MAP sensor harness connector. Is the resistance above 100 k/ohms? If yes, go to next step. If no, repair the excessive resistance between ground and the (K6) 5-volt supply circuit.
  13. Turn the ignition off. Connect the PCM harness connectors. Ignition on, engine not running. With the DRBIII® scan tool, monitor the MAP sensor voltage. Connect a jumper wire between the (Kl) MAP signal circuit and the (K4) sensor ground circuit. Cycle the ignition switch from off to on. Does the DRBIII® scan tool display MAP voltage from approximately 4.9 volts to below 0.5 of a volt? If yes, replace the MAP sensor. If no, go to next step.
    NOTE: Remove the jumper wire before continuing.
    14. CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool (8815) to perform diagnosis.
  14. Turn the ignition off. Disconnect the PCM harness connectors. Measure the resistance of the (Kl) MAP signal circuit from the MAP sensor harness connector to the appropriate terminal of Miller Special Tool (8815). Is the resistance below 5.0 ohms? If yes, go to next step. If no, repair the excessive resistance in the (Kl) MAP signal circuit.
  15. Measure the resistance between ground and the (K1) MAP signal circuit at the MAP sensor harness connector. Is the resistance above 100 k/ohms? If yes, go to next step. If no, repair the excessive resistance between ground and the (Kl) MAP signal circuit.
    16. CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool (8815) to perform diagnosis.
  16. Measure the resistance of the (K4) sensor ground circuit from the MAP sensor harness connector to the appropriate terminal of Miller Special Tool (8815). Is the resistance below 5.0 ohms? If yes, go to next step. If no, repair the excessive resistance in the (K4) sensor ground circuit.
    17. NOTE: Before continuing, disconnect the PCM harness connector and check the related wiring terminals for corrosion, damage or terminal push out. Repair as necessary.
  17. Using the wiring diagram 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, replace and program the PCM. See PROGRAMMING .
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