Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Communication Error
It is possible to get a test fail error from a scan tool when initiating a test or viewing PIDs. The communication error could be caused by operator error, the vehicle wiring or connectors, or the powertrain control module (PCM) and other control modules connected to the DLC wiring. The PCM responds to a scan tool whenever the scan tool requests a test. Some are normal responses to valid requests. The others are communication error responses. If the scan tool displays any of the test fail error responses, reinitialize the scan tool. If the error is still present, refer to PINPOINT TEST AE - UNABLE TO ACTIVATE SELF TEST/SCP COMMUNICATION ERROR/DTC NOT LISTED , after checking the scan tool connections, cable/adapters, and entry of vehicle information. Verify the power take-off system or auxiliary idle control (if equipped) is off when trying to carry out the self-tests.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.