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 MANUALSCHEVROLET1987SUBURBAN R20, 5.7 K, STANDARDREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCETESTING & DIAGNOSISCCC TBI TESTS W/CODESDIAGNOSTIC CHARTSCHART A4 - INJECTOR CIRCUIT (2.8/4.3/5.0/5.7/7.4L)TEST DESCRIPTION
1987 Chevrolet Suburban R20, 5.7 K, Standard
Test Description
1987 Chevrolet Suburban R20, 5.7 K, StandardSECTION Test Description
NOTE:
Test numbers refer to test numbers on diagnostic chart.
- These tests will determine if the ignition module is generating a reference pulse, if wiring is at fault or if ECM is at fault. Touch and connect a 12-volt test light to circuit No. 430, a reference pulse should be generated. If injector test light blinks, ECM and wiring are okay.
- This tests for 12 volts to injector. It will also determine if there is a short to voltage on ECM side of circuit.
- This tests for continuity to ECM.
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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.