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.

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HOMESERVICE MANUALSCHEVROLET1989STEP VAN P20, 4.8 T, AUTOMATIC, 400/M40REPAIR AND DIAGNOSISENGINE PERFORMANCESYSTEMCCC TBI TESTS W/CODESDIAGNOSTIC CHARTSEGR SYSTEM CHECK (2.5L/4.3L/5.0L/5.7L UNDER 8500 GVW)DIAGNOSTIC AIDS

1989 Chevrolet Step Van P20, 4.8 T, Automatic, 400/M40

Diagnostic Aids

1989 Chevrolet Step Van P20, 4.8 T, Automatic, 400/M40SECTION Diagnostic Aids

Before replacing ECM, use an ohmmeter to check resistance of each ECM-controlled relay and solenoid coil. Replace any solenoid if resistance measures less than 20 ohms.

Fig 1: EGR System Check Flow Chart (2.5L, 4.3L, 5.0L & 5.7L Under 8500 GVW)

RENDER: 1.0x

NO RELATED

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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.