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.
Step 3.0 Perform KOEO Self-Test: Begin
Start engine and run until at operating temperature.
Turn key OFF and wait 10 seconds. On vehicles equipped with 4.9L engines only, depress clutch pedal for the rest of the KOEO test. On vehicles equipped with 7.3L diesel engine only, depress throttle (WOT) for the rest of the KOEO test.
For all, activate self-test procedure:
- VOM: Jumper Self-Test Input (STI) single terminal pigtail to SIG RTN terminal at the Self-Test connector. See Figure.
- STAR Tester: Latch the center button in the down position.
- "Check Engine" or "Service Engine Soon" Light (MIL): Jumper Self-Test Input (STI) single terminal pigtail to SIG RTN terminal at the Self-Test connector. See Figure. Service Codes will be flashed on the Light.
- Scan Tool: As described by scan tool manufacturer.
Turn key ON, leaving engine off. Record all On-Demand and Continuous Codes received. Is an On-Demand pass code 11 present (11 or 11-10-any code)?
Use the Manual With the Right Hardware
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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.