Customer Concern: The customer is experiencing an intermittent no start on his 2002 Nissan Pathfinder 3.5L. There is no ground for the fuel pump relay when the problem occurs. And there are no codes.
Tests/Procedures:
1. See if the security light comes on key on or cranking when the engine will not start, indicating an immobilizer system malfunction.
2. See if the Malfunction Indicator Light (MIL) comes on key on when the problem occurs.
3. Check the ECM powers and grounds.
4. Verify the ECM terminal connections are clean and tight.
5. Ground the fuel pump relay on the Pink/Blue wire at terminal 28 of the ECM and see if the fuel pump comes on and if the engine will start and run indicating it has spark and injector pulse.
Potential Causes: Power or ground problem, immobilizer problem, wiring harness/connection or the ECM.
Confirmed Fix: Immobilizer problem, ECM programming.
Tech Tips: The ECM should turn the fuel pump relay on to turn the fuel pump on for a second or so with the key on even without cranking. The immobilizer system typically shuts down the fuel injectors. On some models, the immobilizer system can shut down the ignition and fuel pump as well.
Courtesy of IDENTIFIX.
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