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.
Code 78
Condition is: engine speed less than 1000 RPM, open or short fuel pump circuit for more than one second, open in input circuit of fuel pump ECM or open/short in diagnostic signal line (DI) of fuel pump ECM. Probable cause: open or short in fuel pump ECM circuit, defective fuel pump ECM, fuel pump, faulty ECM power source circuit or defective ECM.
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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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.