Inspection and Verification - Engine Performance

Some engines and transmissions are equipped with PTLP (powertrain limiting and protection) strategy that will limit power under various conditions to protect the engine and the transmission.

1. Verify the customer concern.
2. Visually inspect for obvious signs of mechanical or electrical damage.
3. If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.
4. NOTE: Make sure to use the latest scan tool software release.

   If the cause is not visually evident, connect the scan tool to the DLC.

5. NOTE: The VCM LED prove out confirms power and ground from the DLC are provided to the VCM.

   If the scan tool does not communicate with the VCM:

   • check the VCM connection to the vehicle.
   • check the scan tool connection to the VCM.
   • check for No Power To The Scan Tool, to diagnose no power to the scan tool. REFER to: Communications Network .

6. If the scan tool does not communicate with the vehicle:
   • verify the ignition key is in the ON position.
   • verify the scan tool operation with a known good vehicle.
   • to diagnose no response from the PCM, REFER to: Communications Network .

7. Carry out the network test.
   • If the scan tool responds with no communication for one or more modules, REFER to: Communications Network .
   • If the network test passes, retrieve and record continuous memory DTCs.

8. Clear the continuous DTCs and carry out the self-test diagnostics for the PCM.
9. If the DTCs retrieved are related to the concern, refer to the appropriate Electronic Engine Controls article.
10. If no DTCs related to the concern are retrieved, GO to Symptom Chart - Engine Performance .