<ul> <li><b>Engine Light ON (or Service Engine Soon Warning Light)</b>: The illumination of the engine light indicates a detected issue within the fuel transfer pump relay control circuit. This could be due to high voltage in the circuit.</li> <li><b>Poor Engine Performance</b>: High voltage in the fuel transfer pump relay control circuit can lead to inconsistent fuel delivery, causing the engine to run poorly or even stall.</li> <li><b>Difficulty Starting the Engine</b>: If the fuel transfer pump relay is not functioning correctly due to high voltage, the engine may have trouble starting as it may not receive the necessary fuel pressure.</li> <li><b>Fuel Pump Noise</b>: An abnormal noise from the fuel pump could indicate that it is working harder than usual due to high voltage in the relay control circuit.</li> </ul>

<ul><li>The secondary fuel pump relay may be faulty, causing improper voltage regulation.</li><li>An open or shorted harness in the secondary fuel pump relay can disrupt the circuit.</li><li>Poor electrical connections in the secondary fuel pump relay circuit can lead to high voltage issues.</li><li>A malfunctioning Engine Control Module (ECM) can incorrectly control the relay, resulting in high voltage.</li></ul>

<ul> <li><b>Check Technical Service Bulletins (TSBs)</b>: Research TSBs for the specific vehicle by year, model, and power plant to identify any known issues or manufacturer recommendations related to DTC P2634.</li> <li><b>Visual Inspection</b>: Inspect the fuel transfer pump relay and its associated wiring for any signs of damage, corrosion, or loose connections.</li> <li><b>Test Relay Operation</b>: Use a multimeter to test the fuel transfer pump relay for proper operation. Check for continuity and ensure the relay is functioning correctly.</li> <li><b>Check Voltage at Relay</b>: Measure the voltage at the fuel transfer pump relay control circuit. Ensure the voltage is within the manufacturer's specified range.</li> <li><b>Inspect Fuel Transfer Pump</b>: Inspect the fuel transfer pump for any signs of malfunction or failure. Ensure it is receiving the correct voltage and operating as expected.</li> <li><b>Check Control Module</b>: Verify that the control module responsible for the fuel transfer pump relay is functioning correctly. Check for any software updates or reprogramming needs.</li> <li><b>Clear Codes and Test Drive</b>: After performing necessary repairs or replacements, clear the DTC codes and conduct a test drive to ensure the issue is resolved and the code does not reappear.</li></ul>

<p>The DTC code P2634 indicates a high voltage issue in the Fuel Transfer Pump Relay Control Circuit. This is a critical issue as it can lead to fuel delivery problems, causing engine stalling or failure to start. Immediate action is required to inspect and repair the relay control circuit to prevent potential engine damage and ensure vehicle safety.</p><ul><li><b>Potential Risks:</b> Engine stalling, failure to start, possible engine damage.</li><li><b>Immediate Actions:</b> Inspect and repair the relay control circuit, check for wiring issues, and ensure proper voltage levels.</li></ul>