Dealing with multiple potential issues, including the throttle body replacement, idle learning, and a possible communication issue

 


Check Fuses Related to OBD II and Communication

  • Since you're having communication issues with the scanner, start by checking the OBD II fuse. It could be labeled as OBD, Data Link Connector (DLC), or Diagnostic in your fuse box. If the fuse is blown, it will prevent the scan tool from reading data.
  • Check the owner's manual for the exact location of the fuse and replace it if necessary.

2. Inspect Wiring for OBD II Port

  • Sometimes, a loose or damaged wire near the OBD II port can cause communication problems. Check the wires leading to the OBD II port under the dashboard for any signs of:
    • Corrosion
    • Loose connections
    • Pin damage
  • Make sure the pins inside the OBD II port are not bent or pushed in.

3. Throttle Body and Idle Relearn

  • After replacing the throttle body, the idle relearn process is critical to reset the car's computer to adapt to the new throttle position.

If you can't perform an idle relearn with a scan tool, you can attempt the manual procedure:

Manual Idle Relearn (without a scan tool):

  1. Ensure the engine is cool before starting.
  2. Start the engine and let it idle in Park for 3 minutes. If the idle speed is still not correct, proceed to the next step.
  3. Turn off the engine, then restart and let it idle for another 3 minutes.
  4. Drive the vehicle for about 10 minutes at various speeds, ideally above 44 mph, as you've tried, to help the ECM relearn the idle.

If this manual method does not work, a scan tool capable of performing a throttle position reset might be needed.

4. Check the Battery and Ground Connections

  • A bad or weak battery can cause communication issues and affect the relearn process. Double-check:
    • Battery voltage: Should be at least 12.6V when the engine is off and around 14V when the engine is running.
    • Battery terminals: Ensure they are clean and tightly connected.
    • Ground connections: Check the ground strap from the engine to the chassis and battery. Loose or corroded grounds can cause many electrical issues.

5. Check for Potential Network Issues (CAN Bus)

Your friend mentioned a network issue, which could mean a CAN Bus communication issue (the system modern cars use to communicate between modules). To troubleshoot this:

  • Inspect the wiring harness that connects various components like the ECU (Engine Control Unit), throttle body, and OBD II port. Look for signs of damage, corrosion, or loose connections.
  • If you notice any frayed or damaged wires, especially in areas prone to movement or heat, they may need to be repaired or replaced.

6. Advanced Scan Tool Needed

Since your standard code reader isn't working, a higher-end tool like the GM Tech 2 or a similar scanner capable of communicating with CAN Bus might be needed. If you're still unable to establish a connection, a shop with such a tool may be necessary to diagnose the underlying issue.

7. Additional Sensors

  • If you still have trouble, check if there are any issues with other sensors, like the Mass Air Flow (MAF) sensor or Throttle Position Sensor (TPS). Both can affect idle and throttle response.
  • A dirty or faulty MAF sensor can throw off the idle control. Cleaning the MAF sensor may help.

Steps Recap:

  1. Check fuses related to OBD II and throttle body.
  2. Inspect wiring at the OBD II port and throttle body.
  3. Perform a manual idle relearn (if scan tool isn't available).
  4. Check battery voltage and ground connections for proper function.
  5. Inspect wiring harnesses for any communication issues.
  6. Use an advanced scan tool capable of reading CAN Bus communication.

Final Thoughts

If you have access to a mechanic or tech who can assist with checking wiring harness continuity or has a more advanced scan tool, it would expedite diagnosing the problem. Additionally, some modern parts stores might allow you to use more advanced readers.

Let me know if you need any clarification on any of the steps!

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