DTC Code P1389 – What does this code mean?

<ul> <li><b>Engine Light ON (or Service Engine Soon Warning Light)</b>: The illumination of the engine light indicates a detected issue with the Auto Shutdown (ASD) relay voltage at the Powertrain Control Module (PCM). This can be caused by a faulty ASD relay, wiring issues, or a malfunctioning PCM.</li> <li><b>Engine Stalling</b>: The engine may stall unexpectedly due to the lack of voltage from the ASD relay to the PCM, which can interrupt the fuel and ignition systems.</li> <li><b>No Start Condition</b>: The vehicle may fail to start if the ASD relay is not providing the necessary voltage to the PCM, preventing the engine from receiving fuel and spark.</li> <li><b>Intermittent Power Loss</b>: Drivers may experience intermittent power loss as the PCM intermittently loses voltage from the ASD relay, affecting engine performance.</li> </ul>

<ul><li>The Auto Shutdown (ASD) Relay may be faulty, preventing proper voltage supply to the Powertrain Control Module (PCM).</li><li>An open or shorted ASD Relay harness can disrupt the electrical flow, causing the PCM to not receive the necessary voltage.</li><li>Poor electrical connections in the ASD Relay circuit can lead to intermittent or complete loss of voltage to the PCM.</li><li>A malfunctioning PCM itself can fail to detect or process the voltage from the ASD Relay correctly.</li></ul>

<ul> <li><b>Initial Inspection</b>: Check the battery voltage and ensure it is within the manufacturer's specifications. Inspect the ASD relay for any visible damage or corrosion.</li> <li><b>ASD Relay Function Test</b>: Using a multimeter, test the ASD relay for proper operation. Ensure the relay clicks when activated and that there is continuity between the appropriate terminals.</li> <li><b>Check ASD Relay Circuit</b>: Inspect the wiring and connectors between the ASD relay and the PCM for any signs of damage, corrosion, or loose connections. Repair or replace as necessary.</li> <li><b>PCM Voltage Check</b>: Measure the voltage at the PCM connector to ensure it is receiving the correct voltage from the ASD relay. Compare the readings with the manufacturer's specifications.</li> <li><b>Scan for Additional Codes</b>: Use an OBD-II scanner to check for any additional DTCs that may provide further insight into the issue. Address any related codes such as P1399 if present.</li> <li><b>Test PCM Ground</b>: Verify that the PCM has a good ground connection. Check the ground wires and connections for continuity and repair any issues found.</li> <li><b>Replace ASD Relay</b>: If all tests indicate the ASD relay is faulty, replace it with a new one and clear the DTC code. Re-test the system to ensure the issue is resolved.</li></ul>

<p>The DTC code P1389 indicates <b>No Auto Shutdown Relay Voltage At Powertrain Control Module</b>. This is a critical issue as it can lead to the engine stalling or not starting at all. Immediate actions should include checking the ASD relay, wiring, and connections. Delayed repair can result in complete engine failure and potential safety hazards.</p>