Main Relay (Computer/Fuel System): Testing and Inspection

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INSPECTION






1. Remove engine main relay. (Marking: engine main)





2. Inspect relay continuity.
(a) Check that there is continuity between terminals 1 and 2.
If there is no continuity, replace the relay.
(b) Check that there is no continuity between terminals 3 and 5.
If there is continuity, replace the relay.





3. Inspect relay operation.
(a) Apply battery voltage across terminals 1 and 2.
(b) Using an ohmmeter, check that there is continuity between terminals 3 and 5.
If there is no continuity, replace the relay.
4. Reinstall engine main relay.

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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.